Clinical Diagnosis

Formal diagnostic criteria do not exist. The clinical findings of Lenz microphthalmia syndrome (LMS) include:

• Unilateral or bilateral microphthalmia and/or anophthalmia that may be symmetric or asymmetric
  • Anophthalmia refers to the histologic diagnosis of complete absence of the globe in the presence of ocular adnexae (eyelids, conjunctiva, and lacrimal apparatus). CT or MRI scan of the orbit shows absence of ocular tissue, optic nerve, and extraocular muscles.
    
    Note: The term "clinical anophthalmia" should be used for severe microphthalmia when the globe is not detectable on physical examination.
  • "Simple microphthalmia" or "pure microphthalmia" describes a globe that is reduced in total axial length (TAL), has all structural elements intact, and retains some vision. Mild simple microphthalmia can be identified by measuring the axial length of the globe with A-scan ultrasonography. Total axial length of the neonatal eye is normally near 17 mm; an age-adjusted total axial length below the fifth centile defines microphthalmia. The mean total axial length of the adult eye is 23.8 mm; a total axial length of less than 18.5 mm defines microphthalmia.
  • Coloboma is present in approximately 60% of microphthalmic eyes [Ng et al 2002], with severity ranging from isolated iris coloboma to coloboma of the ciliary body, choroid, and optic disk.
  • Congenital cystic eye has not been observed in LMS.
• Extraocular malformations that vary within and among families
  • Hypospadias, cryptorchidism, renal aplasia/hypoplasia, hydroureter (77% of individuals)
  • Simple, anteverted, abnormally modeled ears (63%)
  • Abnormal shape of incisors, irregularly spaced teeth (48%)
  • Duplicated thumbs, syndactyly, clinodactyly, camptodactyly (44%)
  • Microcephaly (37%)
  • Narrow/sloping shoulders, underdeveloped clavicles, kyphoscoliosis, exaggerated lumbar lordosis, long cylindrical thorax, webbed neck (26%)
  • Cleft lip/palate (7%)
• Intellectual disability ranging from mild to severe (63%)
• Family history consistent with X-linked recessive inheritance

Testing

Karyotype is normal.

Testing Strategy

To confirm/establish the diagnosis in a male with features of LMS

1.

Perform targeted sequencing for the BCOR mutation p.Pro85Leu.

2.

If negative for the p.Pro85Leu mutation, consider sequencing the entire gene.

Carrier testing for at-risk relatives

• Carriers are heterozygotes for this X-linked disorder and may develop clinical findings related to the disorder.
• Identification of female carriers requires either
  • Prior identification of the disease-causing mutation in the family; or
  • If an affected male is not available for testing, molecular genetic testing first by sequence analysis, and then, if no mutation is identified, by methods to detect gross structural abnormalities.

Prenatal diagnosis and preimplantation genetic diagnosis (PGD) for at-risk pregnancies require prior identification of the disease-causing mutation in the family.

Genetically Related (Allelic) Disorders

Oculofaciocardiodental (OFCD) syndrome is also associated with mutations in BCOR [Ng et al 2004, Horn et al 2005, Oberoi et al 2005].

OFCD syndrome is inherited in an X-linked dominant pattern with male lethality.

Females with OFCD syndrome may have congenital cataracts as the sole ocular manifestation or unilateral/bilateral microphthalmia with congenital cataracts. Microphthalmia is less severe in OFCD syndrome than in LMS.

Extraocular features include long narrow face, broad nasal tip with separated nasal cartilage, cleft palate, submucous cleft palate, cardiac anomalies (ventricular septal defect, atrial septal defect, floppy mitral valve) and dental anomalies (retained deciduous teeth, canine radiculomegaly, root dilacerations, and oligodontia).

Females with OFCD syndrome have normal intelligence, in contrast to males with LMS, who often have developmental delay/intellectual disability, microcephaly, and structural CNS abnormalities.

The majority of individuals with OFCD syndrome analyzed thus far have detectable BCOR mutations [Ng et al 2004, Horn et al 2005, Hilton et al 2009]. Two BCOR deletions that encompass several exons have been observed and can be detected by targeted array CGH.

Individuals with OFCD syndrome have mutations that are predicted to prematurely truncate the BCOR protein. In hemizygous males, truncating mutations are hypothesized to lead to a complete loss of BCOR function and are presumed to be lethal. Truncating BCOR mutations in females lead to haploinsufficiency and a milder phenotype. All families with OFCD syndrome have unique mutations.

Based on the known cases of OFCD syndrome scanned for BCOR mutations, penetrance is complete.

Three females with features of OFCD syndrome but with notable absence of dental radiculomegaly did not have identifiable BCOR mutations [Hilton et al 2009].

Other. Isolated (nonsyndromic) forms of microphthalmia have been mapped to the proximal p to q arm of the X chromosome [Lehman et al 2001].

Natural History

The phenotype of Lenz microphthalmia syndrome, microphthalmia with developmental delay and skeletal and urogenital anomalies, linked to the MCOPS1 locus cannot be distinguished from the LMS phenotype caused by mutations in BCOR (MOCPS2 locus).

Lenz microphthalmia syndrome has a wide spectrum of ocular and extraocular abnormalities.

Eyes. The eyes may be asymmetrically affected. One globe can be of normal size while the other is microphthalmic. Severity can range from mild microphthalmia with retained vision to severe microphthalmia or clinical anophthalmia with blindness. Microphthalmia is often accompanied by microcornea and reduction in the size of the anterior segment of the eye, which predispose to the development of glaucoma.

Since mild microphthalmia may not be obvious on clinical examination, individuals with LMS with retained vision may not be identified until the first ophthalmologic examination when high hyperopia (+7 to +11 diopters) secondary to a foreshortened posterior segment of the globe is diagnosed.

Cataracts may be present.

Nystagmus may be present secondary to impaired vision.

Absence or diminished size of the globe may cause secondary underdevelopment of the bony orbits, shortened palpebral fissures, and fusion of the eyelid margins (ankyloblepharon).

Craniofacial. The occurrence of congenital microcephaly is variable. Affected individuals may be normocephalic or dolichocephalic.

Ears may be low set, anteverted, posteriorly rotated, simple, cup shaped, or abnormally modeled. Preauricular tags may be present.

Hearing loss has been observed.

Cleft lip/palate or high arched palate is present in approximately 40% of individuals [Ng et al 2002].

Dental development may be delayed. Nonspecific dental findings include irregularly shaped, missing, or widely spaced teeth.

Genitourinary. Urogenital anomalies are the most frequent associated findings, reported in approximately 77% of individuals [Ng et al 2002]. These include hypospadias, cryptorchidism, renal hypoplasia/aplasia, and hydroureter.

Limbs. Hand findings include duplicated and/or proximally placed thumbs, cutaneous syndactyly, clinodactyly, and camptodactyly.

Skeletal. Long cylindrical thorax with sloping, narrow shoulders, underdeveloped clavicles, or thinning of the lateral third of the clavicles on x-ray as well as kyphoscoliosis and exaggerated lumbar lordosis have been seen in some families.

Cognitive/neurologic. Cognitive impairment varies within and among families. Approximately 60% of affected males have mild-to-severe intellectual disability or developmental delay [Ng et al 2002].

Motor development may be delayed.

Seizures, behavioral disturbance, and self-mutilation may manifest in males with severe intellectual disability. Sleep-wake cycles can be disturbed because of lack of normal diurnal variation.

Cranial MRI often reveals absent or hypoplastic optic nerves and optic chiasm. In addition, hypoplasia of the corpus callosum and cingulate gyrus has been noted. The latter is often clinically silent.

Genotype-Phenotype Correlations

No genotype-phenotype correlations are known.

Both males reported with LMS and a BCOR mutation had the p.Pro85Leu mutation; however, the second reported male exhibited radioulnar synostosis, which occurs in 32% of those with oculofaciocardiodental (OFCD) syndrome (see Genetically Related Disorders). Thus, the presence of radioulnar synostosis in a male with LMS may indicate the presence of a BCOR mutation [Hilton et al 2009].

Penetrance

An insufficient number of cases of BCOR-related Lenz microphthalmia exist to comment on penetrance.

Nomenclature

Lenz microphthalmia syndrome has been referred to as Lenz dysplasia, Lenz dysmorphogenetic syndrome, and microphthalmia with multiple associated anomalies (MAA; OMIM 309800). These terms were used to describe the extraocular developmental anomalies and intellectual disability that co-occur with the microphthalmia in affected males. Although the consensus inheritance pattern is X-linked recessive, the term Lenz microphthalmia is used by clinicians for simplex cases (i.e., single occurrence in a family) with a Lenz-like phenotype.

Prevalence

Prevalence in ethnic groups is unknown. Most reported cases are European descent. An African-American family has been studied by several investigators [Ng et al 2002]. A Hispanic family with isolated X-linked colobomatous microphthalmia has been reported [Lehman et al 2001].

Evaluations Following Initial Diagnosis

To establish the extent of disease in an individual diagnosed with Lenz microphthalmia syndrome (LMS), the following evaluations are recommended:

• Physical examination for the presence of anomalies associated with the disorder
• Cranial MRI to estimate the size of the globes for prognosis regarding potential visual function and to detect concurrent CNS malformations such as hypoplastic corpus callosum and cingulate gyrus
• Visual evoked response testing and ophthalmologic examination to help determine visual acuity and/or the potential for vision
• Renal ultrasound examination to evaluate for renal aplasia, hypoplasia, and hydroureter
• Consideration of hearing evaluation during infancy if:
  • Head and neck examination reveals malformations of the auricle or ear canal, presence of skin tags or dimples around the ear, presence of cleft lip or palate, asymmetric facies, and microcephaly;
  • The parents have concerns that the child cannot hear (i.e., infant does not startle to loud noises, awaken to sound, etc). The type of examination should be adjusted for the individual's cognitive level to allow for cooperation and maximize the chance of an informative test (see Deafness and Hereditary Hearing Loss Overview).
• Consideration of sleep evaluation if parents report excessive daytime somnolence, altered sleep-wake cycles, difficulty awakening the child or getting the child to fall asleep, apnea, loud snoring, and/or difficulty breathing while asleep

Treatment of Manifestations

Individuals with anophthalmos or extreme microphthalmos benefit from regular evaluations by an ocularist for placement of serial enlarging orbital expanders to prevent deformation of facial structures and to encourage normal development of eye lashes and lid margins.

Early intervention with physical therapy and occupational therapy helps to address disturbances of the sleep-wake cycle caused by lack of light perception and problems of delayed gross motor development often observed in children with visual impairment.

Early intervention with special education maximizes cognitive development.

Referral to services for the blind is recommended.

Treatment for hearing loss and sleep disorders is dependent on the specific defect and similar to the general population.

Referral to a sleep disorder specialist may be necessary depending on the individual's history and presentation to determine the appropriate tests.

Dental examinations and cleaning should be instituted to monitor dental hygiene, especially when the affected individual has cognitive developmental delay. Missing and irregularly shaped teeth and wide spacing of teeth are common. Treatment is the same as for the general population in restoring masticatory function.

Prevention of Secondary Complications

If cardiac valvular abnormalities are present, antibiotic prophylaxis prior to dental care and specific medical procedures is necessary as for the general population.

Surveillance

The following are appropriate:

• Annual ophthalmologic examination for those with residual vision given the predisposition to glaucoma and high hyperopia from foreshortening of the globe
• Monitoring of renal function (BUN, creatinine, and urine analysis) in those with known renal/ureteral anomalies
• Developmental assessments performed with each well-child visit as recommended by the American Academy of Pediatrics. More frequent and specialized assessments are tailored to each child if development is not on track.
• Lifelong case management to help affected individuals gain access to social services and assistive devices for the blind.

Agents/Circumstances to Avoid

In those with residual vision, dilating drops and medications that may dilate the pupils (i.e., antihistamines, decongestants, tricyclic antidepressants) should be used in consultation with an ophthalmologist, because of the narrow anterior chamber and risk for angle closure glaucoma.

Evaluation of Relatives at Risk

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

Therapies Under Investigation

Search ClinicalTrials.gov 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.

Mode of Inheritance

Lenz microphthalmia syndrome is inherited in an X-linked recessive manner.

Risk to Family Members

Parents of a proband

• The father of an affected male will neither have the disease nor be a carrier of the mutation.
• In a family with more than one affected male, the mother of an affected male is an obligate carrier.
• If only one male in the family is affected, the mother may be a carrier or the affected male may have a de novo gene mutation, in which case the mother is not a carrier. The frequency of de novo mutations is not known.

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

• If the mother is a carrier, the chance of transmitting the mutation in each pregnancy is 50%. Male sibs who inherit the mutation will be affected; female sibs who inherit the mutation will be carriers and will not be affected.
• If the mother is not a carrier, the risk to sibs is low but greater than that of the general population because of the possibility of germline mosaicism.

Offspring of a proband. The majority of males with Lenz microphthalmia syndrome do not have children, possibly as a result of infertility or decreased reproductive fitness secondary to cognitive impairment. Males who are capable of reproducing pass the disease-causing mutation to all of their daughters and none of their sons.

Other family members. The proband's maternal aunts and their offspring may be at risk of being carriers or being affected (depending on their gender, family relationship, and the carrier status of the proband's mother).

Carrier Detection

Carrier testing using molecular genetic techniques is possible if the disease-causing mutation in the family is known.

Related Genetic Counseling Issues

Family planning

• The optimal time for discussion of genetic risk, clarification of carrier status, and discussion of the availability of prenatal 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 carriers or are at risk of being carriers.

DNA banking is the storage of DNA (typically extracted from white blood cells) for possible future use. Because it is likely that testing methodology and our understanding of genes, mutations, and diseases will improve in the future, consideration should be given to banking DNA of affected individuals.

Prenatal Testing

Ultrasound examination. Prenatal ultrasound examination at 18 weeks' gestation can be offered to mothers of an affected male and to female sibs of a proband of indeterminate carrier status to evaluate fetal renal development. No data exist regarding the effectiveness of screening for other malformations in fetuses at risk for LMS.

Note: Gestational age is expressed as menstrual weeks calculated either from the first day of the last normal menstrual period or by ultrasound measurements.

Molecular genetic testing. If the BCOR mutation has been identified in a family member, prenatal testing is possible for pregnancies at increased risk. The usual procedure is to determine fetal sex by performing chromosome analysis on fetal cells obtained by chorionic villus sampling (CVS) at approximately ten to 12 weeks' gestation or by amniocentesis usually performed at about 15 to 18 weeks' gestation. If the karyotype is 46,XY, DNA from fetal cells can be analyzed for the known disease-causing mutation.

Note: Gestational age is expressed as menstrual weeks calculated either from the first day of the last normal menstrual period or by ultrasound measurements.

Preimplantation genetic diagnosis (PGD) may be an option for some families in which the disease-causing mutation has been identified.

Literature Cited

1. Forrester S, Kovach MJ, Reynolds NM, Urban R, Kimonis V. Manifestations in four males with and an obligate carrier of the Lenz microphthalmia syndrome. Am J Med Genet. 2001;98:92–100. [PubMed: 11426460]
2. Graham CA, Redmond RM, Nevin NC. X-linked clinical anophthalmos. Localization of the gene to Xq27-Xq28. Ophthalmic Paediatr Genet. 1991;12:43–8. [PubMed: 1679229]
3. Hilton E, Johnston J, Whalen S, Okamoto N, Hatsukawa Y, Nishio J, Kohara H, Hirano Y, Mizuno S, Torii C, Kosaki K, Manouvrier S, Boute O, Perveen R, Law C, Moore A, Fitzpatrick D, Lemke J, Fellmann F, Debray FG, Dastot-Le-Moal F, Gerard M, Martin J, Bitoun P, Goossens M, Verloes A, Schinzel A, Bartholdi D, Bardakjian T, Hay B, Jenny K, Johnston K, Lyons M, Belmont JW, Biesecker LG, Giurgea I, Black G. BCOR analysis in patients with OFCD and Lenz microphthalmia syndromes, mental retardation with ocular anomalies, and cardiac laterality defects. Eur J Hum Genet. 2009;17:1325–35. [PMC free article: PMC2826145] [PubMed: 19367324]
4. Horn D, Chyrek M, Kleier S, Lüttgen S, Bolz H, Hinkel GK, Korenke GC, Riess A, Schell-Apacik C, Tinschert S, Wieczorek D, Gillessen-Kaesbach G, Kutsche K. Novel mutations in BCOR in three patients with oculo-facio-cardio-dental syndrome, but none in Lenz microphthalmia syndrome. Eur J Hum Genet. 2005;13:563–9. [PubMed: 15770227]
5. Lehman DM, Sponsel WE, Stratton RF, Mensah J, Macdonald JC, Johnson-Pais TL, Coon H, Reveles XT, Cody JD, Leach RJ. Genetic mapping of a novel X-linked recessive colobomatous microphthalmia. Am J Med Genet. 2001;101:114–9. [PubMed: 11391653]
6. Ng D, Hadley DW, Tifft CJ, Biesecker LG. Genetic heterogeneity of syndromic X-linked recessive microphthalmia-anophthalmia: is Lenz microphthalmia a single disorder? Am J Med Genet. 2002;110:308–14. [PubMed: 12116202]
7. Ng D, Thakker N, Corcoran CM, Donnai D, Perveen R, Schneider A, Hadley DW, Tifft C, Zhang L, Wilkie AO, van der Smagt JJ, Gorlin RJ, Burgess SM, Bardwell VJ, Black GC, Biesecker LG. Oculofaciocardiodental and Lenz microphthalmia syndromes result from distinct classes of mutations in BCOR. Nat Genet. 2004;36:411–6. [PubMed: 15004558]
8. Oberoi S, Winder AE, Johnston J, Vargervik K, Slavotinek AM. Case reports of oculofaciocardiodental syndrome with unusual dental findings. Am J Med Genet A. 2005;136:275–7. [PubMed: 15957158]

Suggested Reading

1. Martínez-Garay I, Tomás M, Oltra S, Ramser J, Moltó MD, Prieto F, Meindl A, Kutsche K, Martínez F. A two base pair deletion in the PQBP1 gene is associated with microphthalmia, microcephaly, and mental retardation. Eur J Hum Genet. 2007;15:29–34. [PubMed: 17033686]

Revision History

• 29 April 2010 (me) Comprehensive update posted live
• 27 July 2007 (cd) Revision: clinical testing for BCOR mutations no longer available
• 6 September 2006 (cd) Revision: FISH, mutation scanning, linkage analysis, and X-chromosome inactivation studies no longer clinically available for BCOR
• 23 June 2006 (ca) Comprehensive update posted to live Web site
• 12 April 2005 (dn) Revision: BCOR testing clinically available
• 13 May 2004 (me) Comprehensive update posted to live Web site
• 5 February 2004 (dn) Revision: Molecular Genetics
• 4 June 2002 (me) Review posted to live Web site
• 8 February 2002 (dn) Original submission

Note: Pursuant to 17 USC Section 105 of the United States Copyright Act, the GeneReview ‘Lenz Microphthalmia Syndrome’ is in the public domain in the United States of America.