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Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024.

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Phosphoribosylpyrophosphate Synthetase Deficiency

Synonym: PRS Deficiency

, PhD and , MBBS, PhD.

Author Information and Affiliations

Initial Posting: ; Last Update: June 8, 2023.

Estimated reading time: 23 minutes

Summary

Clinical characteristics.

Phosphoribosylpyrophosphate synthetase (PRS) deficiency, an X-linked disorder, is a phenotypic continuum comprising three disorders previously thought to be clinically distinct: Arts syndrome, Charcot-Marie-Tooth neuropathy X type 5 (CMTX5), and X-linked nonsyndromic sensorineural hearing loss (DFNX1). In affected males, the PRS deficiency phenotypic spectrum ranges from severe congenital profound sensorineural hearing loss, intellectual disability, delayed motor development, and progressive ophthalmologic involvement (retinal dystrophy and optic atrophy) to normal cognitive abilities and relatively later-onset, somewhat milder manifestations, such as mild sensorineural hearing loss, peripheral neuropathy, and gait ataxia.

Heterozygous females can show isolated and/or milder manifestations in the PRS deficiency spectrum. To date, 40 families with PRS deficiency have been reported.

Diagnosis/testing.

The diagnosis of PRS deficiency is established in a male proband with suggestive findings and a hemizygous pathogenic variant in PRPS1 identified by molecular genetic testing. The diagnosis of PRS deficiency is usually established in a female proband with suggestive findings and a heterozygous pathogenic variant in PRPS1 identified by molecular genetic testing.

Management.

Treatment of manifestations: There is no cure for PRS deficiency. Supportive care to improve quality of life, maximize function, and reduce complications can include multidisciplinary care by specialists in neurology, physiatry, physical therapy, occupational therapy, audiology, otolaryngology, ophthalmology and low vision services, education, and medical genetics.

Surveillance: Monitoring existing manifestations, the individual's response to supportive care, and the emergence of new manifestations involves scheduled follow up with the treating specialists.

Genetic counseling.

PRS deficiency is inherited in an X-linked manner. If the mother of the proband has a PRPS1 pathogenic variant, the chance of transmitting it in each pregnancy is 50%; if the father of the proband has a PRPS1 pathogenic variant, he will transmit it to all his daughters and none of his sons. Males who inherit the pathogenic variant will be affected. Females who inherit the pathogenic variant will be heterozygotes and will be asymptomatic or show manifestations of PRS deficiency that are typically isolated and/or milder than manifestations in hemizygous males with the same pathogenic variant. The ratio of X-chromosome inactivation adds an additional variable in predicting clinical outcome in females who inherit a PRPS1 pathogenic variant. Once the PRPS1 pathogenic variant has been identified in an affected family member, heterozygote testing for at-risk female relatives and prenatal and preimplantation genetic testing are possible.

GeneReview Scope

With the current widespread use of multigene panels and comprehensive genomic testing based on an unbiased (i.e., not phenotype-driven) approach, it has become apparent that the phenotypic continuum associated with phosphoribosylpyrophosphate synthetase (PRS) deficiency is comprised of clusters encompassing three previously clinically distinct disorders – Arts syndrome, Charcot-Marie-Tooth neuropathy X type 5 (CMTX5), and X-linked nonsyndromic sensorineural hearing loss (DFNX1). PRS deficiency refers to this entire phenotypic spectrum and emphasizes the need to evaluate an individual with a PRPS1 pathogenic missense variant that results in loss of function for medically actionable manifestations within the spectrum regardless of the clinical findings that prompted molecular genetic testing.

PRS Deficiency: Disorders Previously Clinically Defined in the Phenotypical Continuum

Clinically Defined DisorderMajor Clinical Findings 1
Sensorineural hearing lossPeripheral neuropathyIntellectual disabilityRespiratory infectionOphthalmologic involvement
Arts syndrome + (profound, congenital)++↑ liability+
CMTX5 + (early onset, prelingual)++
DFNX1 2 + (typically late onset) 3

CMTX5 = Charcot-Marie-Tooth neuropathy X type 5; DFNX1 = X-linked nonsyndromic sensorineural hearing loss

1.

Females typically have a less severe presentation than males; the ratio of X-chromosome inactivation adds an additional variable in predicting clinical outcome in females.

2.

Also referred to as DFN2.

3.

Although postlingual progressive nonsyndromic hearing loss is typical, one family had congenital profound nonsyndromic hearing loss [Liu et al 2010].

Diagnosis

For the purposes of this GeneReview, the terms "male" and "female" are narrowly defined as the individual's biological sex at birth as it determines clinical care [Caughey et al 2021].

No consensus clinical diagnostic criteria for phosphoribosylpyrophosphate synthetase (PRS) deficiency have been published.

Suggestive Findings

PRS deficiency should be suspected in a male proband with the following clinical and supportive laboratory findings and family history.

Clinical findings in males

  • Bilateral sensorineural hearing loss (SNHL) that is moderate to profound; prelingual or postlingual in onset; and progressive or non-progressive. Note: Hearing loss that is moderate to profound in a neonate will be detected by newborn hearing screening; however, hearing loss that is mild will not.
    Audiogram shapes are usually residual or flat [Liu et al 2013].
    Temporal bone imaging is normal [Liu et al 2013].
    Vestibular function is normal.
  • Early-onset hypotonia and delayed motor development
  • Peripheral motor neuropathy (axonal with later sensory involvement)
  • Intellectual disability (ID) ranging from nonexistent (DFNX1) to moderate ID (Arts syndrome)
  • Liability to infections especially in the upper respiratory tract
  • Ophthalmologic findings
    • Optic neuronopathy/atrophy
      • Fundoscopic examination shows bilateral optic disc pallor.
      • Visual evoked potentials demonstrate delayed latency and decreased amplitudes of P100.
    • Retinal dystrophy [Mercati et al 2020]
      • Fundoscopic examination can show patches of retinal atrophy.
      • Electroretinogram can show abnormal cone and rod responses.

Supportive laboratory findings in males

  • Serum uric acid concentration is lower than average (0.13-0.16 mmol/L), although still within the normal range (i.e., 0.12-0.35 mmol/L) [de Brouwer et al 2007].
    Note: (1) Serum uric acid concentration is not zero because the enzyme PRS-II, which has the same enzyme activity as the enzyme PRS-I, is active in tissues such as liver, resulting in purine nucleotide synthesis and uric acid production. (2) However, a low/normal serum uric acid concentration may be helpful in ruling out a diagnosis of PRS superactivity, in which serum uric acid concentration is usually high.
  • Purine analysis in urine
    • Absent/low hypoxanthine concentration
    • Normal range of concentration of other purines
    • When individuals with PRS deficiency are on a low-purine diet, the uric acid-to-creatinine ratio in urine may tend to be at the lower end of normal but not zero.

Clinical findings in females. In the most severe phenotype, findings include ophthalmologic manifestations, ataxia, peripheral neuropathy, and hearing loss [Almoguera et al 2014].

Family history is consistent with X-linked inheritance (e.g., no male-to-male transmission). Note: (1) In families segregating a loss-of-function PRPS1 pathogenic variant, hemizygous males are affected and heterozygous females may be asymptomatic or have variable manifestations. (2) Absence of a known family history does not preclude the diagnosis.

Establishing the Diagnosis

Male proband. The diagnosis of PRS deficiency is established in a male proband with suggestive findings and a hemizygous pathogenic (or likely pathogenic) variant in PRPS1 identified by molecular genetic testing (see Table 1).

Female proband. The diagnosis of PRS deficiency is usually established in a female proband with suggestive findings and a heterozygous pathogenic (or likely pathogenic) variant in PRPS1 identified by molecular genetic testing (see Table 1).

Note: (1) Per ACMG/AMP variant interpretation guidelines, the terms "pathogenic variants" and "likely pathogenic variants" are synonymous in a clinical setting, meaning that both are considered diagnostic and both can be used for clinical decision making [Richards et al 2015]. Reference to "pathogenic variants" in this section is understood to include any likely pathogenic variants. (2) Identification of a hemizygous or heterozygous PRPS1 variant of uncertain significance does not establish or rule out the diagnosis.

Molecular genetic testing approaches can include a combination of gene-targeted testing (single gene testing, multigene panel) and comprehensive genomic testing (exome sequencing, genome sequencing). Gene-targeted testing requires that the clinician determine which gene(s) are likely involved (see Option 1), whereas comprehensive genomic testing does not (see Option 2).

Note: Single-gene testing (sequence analysis of PRPS1, followed by gene-targeted deletion/duplication analysis) is rarely useful and typically NOT recommended.

Option 1

An intellectual disability, ataxia, hearing loss, deafness, retinal dystrophy, optic atrophy, or peripheral neuropathy multigene panel that includes PRPS1 and other genes of interest (see Differential Diagnosis) is most likely to identify the genetic cause of the condition while limiting identification of variants of uncertain significance and pathogenic variants in genes that do not explain the underlying phenotype. Note: (1) The genes included in the panel and the diagnostic sensitivity of the testing used for each gene vary by laboratory and are likely to change over time. (2) Some multigene panels may include genes not associated with the condition discussed in this GeneReview. (3) In some laboratories, panel options may include a custom laboratory-designed panel and/or custom phenotype-focused exome analysis that includes genes specified by the clinician. (4) Methods used in a panel may include sequence analysis, deletion/duplication analysis, and/or other non-sequencing-based tests.

For an introduction to multigene panels click here. More detailed information for clinicians ordering genetic tests can be found here.

Option 2

Comprehensive genomic testing does not require the clinician to determine which gene is likely involved. Exome sequencing is the most commonly used; genome sequencing is also possible.

For an introduction to comprehensive genomic testing click here. More detailed information for clinicians ordering genomic testing can be found here.

Table 1.

Molecular Genetic Testing Used in PRS deficiency

Gene 1MethodProportion of Probands with a Pathogenic Variant 2 Detectable by Method
PRPS1 Sequence analysis 3100% 4
Gene-targeted deletion/duplication analysis 5None 4
1.

See Table A. Genes and Databases for chromosome locus and protein.

2.

See Molecular Genetics for information on variants detected in this gene.

3.

Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.

4.

Data collectively provided for PRPS1 pathogenic variants identified in Arts syndrome, CMTX5, and DFNX1. Data derived from the subscription-based professional view of Human Gene Mutation Database [Stenson et al 2020].

5.

Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include a range of techniques such as quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.

Clinical Characteristics

Clinical Description

The phenotype of phosphoribosylpyrophosphate synthetase (PRS) deficiency is now known to be a continuum encompassing three previously clinically defined disorders – Arts syndrome, Charcot-Marie-Tooth neuropathy X type 5 (CMTX5), and X-linked nonsyndromic sensorineural hearing loss (DFNX1). Arts syndrome (characterized by intellectual disability, hypotonia, ataxia, sensorineural hearing impairment, and progressive optic atrophy and/or retinopathy), CMTX5 (characterized by peripheral neuropathy, sensorineural hearing loss, and optic neuropathy), and DFNX1 were initially thought to represent distinct phenotypes. However, following the observation in a single family of a male with features of CMTX5 and Arts syndrome and a female with prelingual DFNX1, Synofzik et al [2014] concluded that these disorders are not distinct entities, but rather clusters on a phenotypic continuum associated with PRS deficiency.

Subsequent reports confirmed this observation and further expanded the PRS deficiency phenotype:

  • Detailed clinical and neurophysiologic examination of males diagnosed with PRPS1-related hearing loss revealed peripheral neuropathy ranging from subclinical axonal motor neuropathy to axonal sensorimotor neuropathy [Robusto et al 2015].
  • Females heterozygous for a PRPS1 pathogenic missense variant were found to have optic atrophy and retinal dystrophy [Almoguera et al 2014].
  • Mercati et al [2020] reported a male with profound developmental delay and multiorgan involvement.

Thus, the phenotypic spectrum of PRS deficiency can range from profound congenital sensorineural hearing impairment, intellectual disability, delayed motor development, and progressive optic atrophy [Arts et al 1993, de Brouwer et al 2007] to relatively later-onset, somewhat milder manifestations, such as mild sensorineural hearing loss, peripheral neuropathy, gait ataxia, and normal cognitive abilities.

To date, 40 families have been identified with PRS deficiency [Mercati et al 2020, Puusepp et al 2020, Rezende Filho et al 2021, Shirakawa et al 2022]. The following description of the phenotypic features associated with this condition is based on these reports.

Affected Males

Sensorineural hearing loss can be prelingual to postlingual with onset ranging from congenital to age 20 years. It can be progressive or non-progressive, and severe to profound [Liu et al 2010, Liu et al 2013, Kim et al 2016].

Early-onset hypotonia and delayed motor development. Hypotonia, which is usually mild, may be noted in infancy. Attainment of motor milestones may be mildly to moderately delayed.

Peripheral motor and sensory neuropathy. Onset of peripheral neuropathy is between ages two and 12 years [de Brouwer et al 2007]. The lower extremities are affected earlier and more severely than the upper extremities. The initial manifestation is often foot drop or gait disturbance. Deep tendon reflexes are usually absent. Motor signs predominate, but impaired sensory function may accompany motor dysfunction or develop during disease progression. With advancing disease, affected individuals may become dependent on crutches or a wheelchair.

Sural nerve biopsy showed the following:

  • Loss of myelinated fibers without signs of demyelination or axonal degeneration in a boy age five years with Arts syndrome from the original Dutch family reported by Arts et al [1993].
  • Mild paranodal demyelination indicative of peripheral neuropathy in a boy age two years, who had absent lower limb deep tendon reflexes and nerve conduction studies indicative of peripheral neuropathy [de Brouwer et al 2007].

Intellectual disability (ID) is mild to moderate. Brain MRI shows nonspecific abnormalities (e.g., reduction of white matter in the brain, which would indicate demyelination) [de Brouwer et al 2007].

Liability to infections, especially upper respiratory tract infections, resulted in death before age six years in 12 of the 15 boys from the two Dutch families reported with Arts syndrome [Arts et al 1993]. During infection, the acute deterioration in muscle strength in the otherwise slowly progressive muscle weakness could result in respiratory failure requiring mechanical ventilation.

Ophthalmologic involvement. Onset of visual impairment is between ages seven and 20 years. Optic neuropathy and retinopathy can progress with time.

Heterozygous Females

Heterozygous females can show isolated and/or milder manifestations, most notably late-onset (age >20 years) hearing impairment that can be either symmetric or asymmetric and ranges from mild to moderate [Liu et al 2013]. In the family described by Almoguera et al [2014], both the female proband and her mother had peripheral neuropathy and ophthalmologic manifestations (retinal dystrophy and optic atrophy). One affected sister had a milder phenotype limited to ophthalmologic findings. Ataxia, hypotonia, and hyperreflexia have been reported as well [Arts et al 1993].

Genotype-Phenotype Correlations

In the wide and continuous spectrum of clinical manifestations associated with PRPS1 missense variants that result in a loss of function, a relationship between the type (location) of disruption of the PRS-I enzyme and phenotype has been suggested. The most severe phenotypes are caused by variants that are predicted to affect allosteric and active sites, and the milder phenotypes are caused by variants that are predicted to disrupt the structure locally [de Brouwer et al 2010].

In females, who predictably have less severe manifestations, the ratio of X-chromosome inactivation adds an additional variable in predicting clinical outcome [Synofzik et al 2014].

Nomenclature

Charcot-Marie-Tooth neuropathy X type 5 (CMTX5) was previously referred to as Rosenberg-Chutorian syndrome [Kim et al 2007].

DFNX1 nonsyndromic hearing loss and deafness was previously referred to as DFN2 (OMIM 304500).

Differential Diagnosis

Intellectual disability. The phenotypic features associated with PRPS1-related intellectual disability are not sufficient to diagnose this condition clinically; all disorders with intellectual disability without other distinctive findings should be considered in the differential diagnosis. See OMIM Phenotypic Series for genes associated with:

Hearing loss. See Genetic Hearing Loss Overview.

Peripheral neuropathy. See Charcot-Marie-Tooth Hereditary Neuropathy Overview.

Management

No clinical practice guidelines for phosphoribosylpyrophosphate synthetase (PRS) deficiency have been published.

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with PRS deficiency, the evaluations summarized in Table 2 (if not performed as part of the evaluation that led to diagnosis) are recommended.

Treatment of Manifestations

There is no cure for PRS deficiency.

Supportive care to improve quality of life, maximize function, and reduce complications is recommended. This can include multidisciplinary care by specialists in neurology, physiatry, physical therapy, occupational therapy, audiology, otolaryngology, ophthalmology and low vision services, education, and medical genetics (see Table 3).

Table 3.

PRS Deficiency: Treatment of Manifestations

Manifestation/ConcernTreatmentConsiderations/Other
Developmental delay /
Intellectual disability
See Developmental Delay / Intellectual Disability Management Issues.
Musculoskeletal/
Activities of daily living
Orthopedics / physical medicine & rehab / PT & OT incl stretching
Hearing
  • See Genetic Hearing Loss Overview, Management.
  • Cochlear implantation in 2 affected males was assoc w/improved communication skills.
Community hearing services through early intervention or school district
Ophthalmologic involvement By ophthalmologistTreatment of refractive errors &/or strabismus
Low vision services
  • Children: through early intervention programs &/or school district
  • Adults: referral to low vision clinic &/or community vision services
Respiratory By pulmonologist &/or infectious disease specialistConsider prophylactic antibiotics where appropriate.
Family/Community
  • Ensure appropriate social work involvement to connect families w/local resources, respite, & support.
  • Coordinate care to manage multiple subspecialty appointments, equipment, medications, & supplies.
  • Ongoing assessment of need for palliative care involvement &/or home nursing
  • Consider involvement in adaptive sports or Special Olympics.

OT = occupational therapy; PT = physical therapy

Developmental Delay / Intellectual Disability Management Issues

The following information represents typical management recommendations for individuals with developmental delay / intellectual disability in the United States; standard recommendations may vary from country to country.

Ages 0-3 years. Referral to an early intervention program is recommended for access to occupational, physical, speech, and feeding therapy as well as infant mental health services, special educators, and sensory impairment specialists. In the US, early intervention is a federally funded program available in all states that provides in-home services to target individual therapy needs.

Ages 3-5 years. In the US, developmental preschool through the local public school district is recommended. Before placement, an evaluation is made to determine needed services and therapies and an individualized education plan (IEP) is developed for those who qualify based on established motor, language, social, or cognitive delay. The early intervention program typically assists with this transition. Developmental preschool is center based; for children too medically unstable to attend, home-based services are provided.

All ages. Consultation with a developmental pediatrician is recommended to ensure the involvement of appropriate community, state, and educational agencies (US) and to support parents in maximizing quality of life. Some issues to consider:

  • IEP services:
    • An IEP provides specially designed instruction and related services to children who qualify.
    • IEP services will be reviewed annually to determine whether any changes are needed.
    • Special education law requires that children participating in an IEP be in the least restrictive environment feasible at school and included in general education as much as possible, when and where appropriate.
    • Vision and hearing consultants should be a part of the child's IEP team to support access to academic material.
    • PT, OT, and speech services will be provided in the IEP to the extent that the need affects the child's access to academic material. Beyond that, private supportive therapies based on the affected individual's needs may be considered. Specific recommendations regarding type of therapy can be made by a developmental pediatrician.
    • As a child enters the teen years, a transition plan should be discussed and incorporated in the IEP. For those receiving IEP services, the public school district is required to provide services until age 21.
  • A 504 plan (Section 504: a US federal statute that prohibits discrimination based on disability) can be considered for those who require accommodations or modifications such as front-of-class seating, assistive technology devices, classroom scribes, extra time between classes, modified assignments, and enlarged text.
  • Developmental Disabilities Administration (DDA) enrollment is recommended. DDA is a US public agency that provides services and support to qualified individuals. Eligibility differs by state but is typically determined by diagnosis and/or associated cognitive/adaptive disabilities.
  • Families with limited income and resources may also qualify for supplemental security income (SSI) for their child with a disability.

Surveillance

To monitor existing manifestations, the individual's response to supportive care, and the emergence of new manifestations, the evaluations listed in Table 4 are recommended.

Evaluation of Relatives at Risk

It is appropriate to clarify the genetic status of apparently asymptomatic older and younger male and female sibs of a proband in order to identify sibs at risk for hearing loss who may benefit from appropriate early support and management.

See Genetic Counseling for issues related to testing of at-risk relatives for genetic counseling purposes.

Therapies Under Investigation

Dietary supplementation with S-adenosylmethionine (SAM) has been investigated in individuals with PRPS1-related disorders [Authors, personal observation].

An anecdotal study suggested that co-therapy of SAM and nicotinamide riboside may be of additional clinical benefit [Lenherr et al 2021].

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Genetic Counseling

Genetic counseling is the process of providing individuals and families with information on the nature, mode(s) of inheritance, and implications of genetic disorders to help them make informed medical and personal decisions. The following section deals with genetic risk assessment and the use of family history and genetic testing to clarify genetic status for family members; it is not meant to address all personal, cultural, or ethical issues that may arise or to substitute for consultation with a genetics professional. —ED.

Mode of Inheritance

Phosphoribosylpyrophosphate synthetase (PRS) deficiency is inherited in an X-linked manner.

Risk to Family Members

Parents of a male proband

  • The father of an affected male will not have the disorder nor will he be hemizygous for the PRPS1 pathogenic variant; therefore, he does not require further evaluation/testing.
  • In a family with more than one affected individual, the mother of an affected male is an obligate heterozygote. Note: If a woman has more than one affected child and no other affected relatives and if the PRPS1 pathogenic variant cannot be detected in her leukocyte DNA, she most likely has germline mosaicism.
  • If a male is the only affected family member (i.e., a simplex case), the mother may be a heterozygote, the affected male may have a de novo PRPS1 pathogenic variant (in which case the mother is not a heterozygote), or the mother may have somatic/germline mosaicism.
    • The frequency of de novo pathogenic variants is not known.
    • Maternal germline mosaicism has not been reported to date but remains a possibility.
  • Molecular genetic testing of the mother is recommended to confirm her genetic status and to allow reliable recurrence risk assessment.

Parents of a female proband

  • A female proband may have inherited the PRPS1 pathogenic variant from either her mother or her father, or the pathogenic variant may be de novo.
  • Detailed evaluation of the parents and review of the extended family history may help distinguish probands with a de novo pathogenic variant from those with an inherited pathogenic variant. Molecular genetic testing of the mother (and possibly the father, or subsequently the father) can determine if the pathogenic variant was inherited.

Sibs of a male proband. The risk to sibs depends on the genetic status of the mother:

  • If the mother of the proband has a PRPS1 pathogenic variant, the chance of transmitting it in each pregnancy is 50%.
    • Males who inherit the pathogenic variant will be affected.
    • Females who inherit the pathogenic variant will be heterozygotes and will be asymptomatic or show manifestations of PRS deficiency that are typically isolated and/or milder than manifestations in hemizygous males with the same pathogenic variant. The ratio of X-chromosome inactivation adds an additional variable in predicting clinical outcome in females who inherit a PRPS1 pathogenic variant. See Clinical Description, Heterozygous Females.
  • If the proband represents a simplex case and if the PRPS1 pathogenic variant cannot be detected in the leukocyte DNA of the mother, the risk to sibs is presumed to be low but greater than that of the general population because of the possibility of maternal germline mosaicism.

Sibs of a female proband. The risk to sibs depends on the genetic status of the parents:

  • If the mother of the proband has a PRPS1 pathogenic variant, the chance of transmitting it in each pregnancy is 50%.
  • If the father of the proband has a PRPS1 pathogenic variant, he will transmit it to all his daughters and none of his sons.
  • If the proband represents a simplex case and if the PRPS1 pathogenic variant cannot be detected in the leukocyte DNA of the mother, the risk to sibs is presumed to be low but greater than that of the general population because of the possibility of parental germline mosaicism.

Offspring of a male proband. Males with PRS deficiency transmit the PRPS1 pathogenic variant to:

  • All of their daughters, who will be heterozygotes and will be asymptomatic or show manifestations of PRS deficiency that are typically isolated and/or milder than manifestations in hemizygous males with the same pathogenic variant (see Clinical Description, Heterozygous Females);
  • None of their sons.

Offspring of a female proband. Women with a PRPS1 pathogenic variant have a 50% chance of transmitting the pathogenic variant to each child.

Other family members. If a parent of the proband also has a pathogenic variant, relatives of the heterozygous/hemizygous parent may be at risk of having a PRPS1 pathogenic variant and manifestations of PRS deficiency.

Note: Molecular genetic testing may be able to identify the family member in whom a de novo pathogenic variant arose, information that could help determine genetic risk status of the extended family.

Heterozygote Detection

Identification of female heterozygotes requires either prior identification of the PRPS1 pathogenic variant in the family or, if an affected male is not available for testing, molecular genetic testing first by sequence analysis, and if no pathogenic variant is identified, by gene-targeted deletion/duplication analysis.

Note: Females who are heterozygous for this X-linked disorder may develop clinical findings related to the disorder (see Clinical Description, Heterozygous Females).

Related Genetic Counseling Issues

Family planning

  • The optimal time for determination of genetic risk and discussion of the availability of prenatal/preimplantation genetic testing is before pregnancy.
  • It is appropriate to offer genetic counseling (including discussion of potential risks to offspring and reproductive options) to young adults who are affected or at risk of having a PRPS1 pathogenic variant.

Prenatal Testing and Preimplantation Genetic Testing

Once the PRPS1 pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible.

Differences in perspective may exist among medical professionals and within families regarding the use of prenatal testing. While most centers would consider use of prenatal testing to be a personal decision, discussion of these issues may be helpful.

Resources

GeneReviews staff has selected the following disease-specific and/or umbrella support organizations and/or registries for the benefit of individuals with this disorder and their families. GeneReviews is not responsible for the information provided by other organizations. For information on selection criteria, click here.

  • Alexander Graham Bell Association for the Deaf and Hard of Hearing
    Phone: 866-337-5220 (toll-free); 202-337-5221 (TTY)
    Fax: 202-337-8314
    Email: info@agbell.org
  • American Association on Intellectual and Developmental Disabilities (AAIDD)
    Phone: 202-387-1968
  • American Society for Deaf Children
    Phone: 800-942-2732 (ASDC)
    Email: info@deafchildren.org
  • BabyHearing.org
    This site, developed with support from the National Institute on Deafness and Other Communication Disorders, provides information about newborn hearing screening and hearing loss.
  • CDC - Child Development
    Phone: 800-232-4636
  • Charcot-Marie-Tooth Association (CMTA)
    Phone: 800-606-2682
    Email: info@cmtausa.org
  • CMT Research Foundation
    Phone: 404-806-7180
    Email: info@cmtrf.org
  • European Charcot-Marie-Tooth Consortium
    Department of Molecular Genetics
    University of Antwerp
    Antwerp Antwerpen B-2610
    Belgium
    Fax: 03 2651002
    Email: gisele.smeyers@ua.ac.be
  • Hereditary Neuropathy Foundation
    Phone: 855-435-7268 (toll-free); 212-722-8396
    Fax: 917-591-2758
    Email: info@hnf-cure.org
  • National Association of the Deaf
    Phone: 301-587-1788 (Purple/ZVRS); 301-328-1443 (Sorenson); 301-338-6380 (Convo)
    Fax: 301-587-1791
    Email: nad.info@nad.org
  • National Ataxia Foundation
    Phone: 763-553-0020
    Email: naf@ataxia.org
  • National Eye Institute
    Phone: 301-496-5248
    Email: 2020@nei.nih.gov
  • RDCRN Patient Contact Registry: Inherited Neuropathies Consortium

Molecular Genetics

Information in the Molecular Genetics and OMIM tables may differ from that elsewhere in the GeneReview: tables may contain more recent information. —ED.

Table A.

Phosphoribosylpyrophosphate Synthetase Deficiency: Genes and Databases

Data are compiled from the following standard references: gene from HGNC; chromosome locus from OMIM; protein from UniProt. For a description of databases (Locus Specific, HGMD, ClinVar) to which links are provided, click here.

Table B.

OMIM Entries for Phosphoribosylpyrophosphate Synthetase Deficiency (View All in OMIM)

301835ARTS SYNDROME; ARTS
304500DEAFNESS, X-LINKED 1; DFNX1
311070CHARCOT-MARIE-TOOTH DISEASE, X-LINKED RECESSIVE, 5; CMTX5
311850PHOSPHORIBOSYLPYROPHOSPHATE SYNTHETASE I; PRPS1

Molecular Pathogenesis

PRPS1 encodes the enzyme phosphoribosyl pyrophosphate synthetase I (PRS-I), which catalyzes the phosphoribosylation of ribose 5-phosphate to 5-phosphoribosyl-1-pyrophosphate, which is necessary for the de novo and salvage pathways of purine and pyrimidine biosynthesis.

Mechanism of disease causation. Missense variants that cause a loss of function of PRPS1

PRPS1-specific laboratory technical considerations. For PRPS1 missense variants of uncertain significance, PRS-I enzyme analysis can be performed. PRS deficiency is confirmed if:

  • PRS-I enzyme activity is absent in erythrocytes (because PRS-I is the only isoform present);
  • PRS-I enzyme activity is significantly lower in fibroblasts than in controls [de Brouwer et al 2007].

Chapter Notes

Author Notes

Contact Dr Arjan de Brouwer or Prof John Christodoulou to inquire about review of PRPS1 variants of uncertain significance.

Acknowledgments

The authors are grateful to the families of the Dutch and Australian patients for providing samples used for biochemical and molecular analyses over a number of years. The research conducted at the Murdoch Children's Research Institute (MCRI) was supported by the Victorian Government's Operational Infrastructure Support Program. The Chair in Genomic Medicine awarded to JC is generously supported by The Royal Children's Hospital Foundation.

Author History

Arjan PM de Brouwer, PhD (2008-present)
John Christodoulou, MBBS, PhD (2008-present)
John A Duley, PhD; University of Queensland (2008-2018)

Revision History

  • 8 June 2023 (bp) Comprehensive update posted live
  • 22 March 2018 (sw) Comprehensive update posted live
  • 29 March 2011 (cd) Revision: edits to Differential Diagnosis
  • 4 January 2011 (cd) Revision: changes to Therapies Under Investigation
  • 18 November 2010 (me) Comprehensive update posted live
  • 21 October 2008 (me) Review posted live
  • 3 June 2008 (apmb) Original submission

References

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