Clinical Description
The most common clinical manifestations of SETBP1 haploinsufficiency disorder (SETBP1-HD) are mild motor developmental delay and hypotonia, speech and language disorder, intellectual disability, attention-deficit/hyperactivity disorder (ADHD), and refractive errors and strabismus.
To date, 47 individuals with SETBP1-HD have been reported [Leonardi et al 2020, Jansen et al 2021, Morgan et al 2021]. The following description of the phenotypic features associated with this condition is based on these reports (Table 2).
Table 2.
SETBP1 Haploinsufficiency Disorder: Frequency of Select Features
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Feature | Frequency of Feature |
---|
Delayed motor milestones | >90% |
Speech and language disorder | >95% |
Intellectual disability | Mild | ≤30% |
Moderate | ~30% |
Severe | ~20% |
Normal or borderline IQ | 20% |
Behavior problems | ADHD-like | 75% |
Other | 13%-25% |
Feeding difficulties | 60% |
Ophthalmologic involvement | 50% |
Excessive drooling | 35% |
Ankyloglossia | 25% |
Digestive problems | >20% |
Cryptorchidism | 20% of males |
Febrile seizures | 20% |
ADHD = attention-deficit/hyperactivity disorder
Delayed Motor Milestones
Gross motor abilities are generally better than fine motor abilities [Jansen et al 2021, Morgan et al 2021]. Ninety-four per cent had generalized motor delay or disorder [Morgan et al 2021]. Hypotonia may be noted in infancy and is commonly observed during childhood.
Sitting, crawling, and walking are delayed. Average age of sitting unsupported is six to 15 months, crawling nine to 19 months, and walking 13 to 36 months.
Fine motor development is delayed in about 70% of affected children. In particular, some children have difficulty with handwriting, which can further affect development of written language and/or exacerbate literacy difficulties [Morgan et al 2021].
Speech and Language Disorder
The terms speech disorder and language disorder are often used interchangeably. Although they often co-occur, each can occur independently, providing evidence that they are separate entities.
Speech involves producing sounds in words with the correct breath support, voicing, resonance, articulation, prosody, and accuracy. Language involves meaning, i.e., the understanding and expression of words (vocabulary) and sentences (grammar).
Speech disorders and language disorders can each be further classified clinically.
Speech disorders. The five most common speech disorder diagnoses are included in Table 3. Children with SETBP1-HD present with speech delay (first words by 18 months in 50%) due to a severe childhood apraxia of speech (seen in 80%) [Morgan et al 2021]. With speech therapy (see Management), childhood apraxia of speech resolves, and dysarthria becomes more evident.
Children with SETBP1-HD also have phonologic disorder which places them at risk for longer-term literacy difficulties (i.e., disorders of spelling and reading).
Due to the childhood apraxia of speech, some children remain minimally verbal for years and augment their speech and language with sign language, gestures, or augmentative and assistive communication devices [Morgan et al 2021]. (See Management.)
Table 3.
Speech Disorders: Definitions
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Speech Disorder | Definition |
---|
Articulation
|
Functional
disorder
| Inability to accurately produce ≥1 sounds (e.g., lisp on /s/) in the absence of explainable cause (e.g., no hearing impairment, no orofacial structural deficits) [Morgan & Günther 2017] |
Structural
disorder
| Inability to accurately produce ≥1 sounds due to orofacial structural impairment (e.g., cleft lip or palate, malocclusion of mandible & maxilla, missing teeth) [Morgan & Günther 2017] |
Phonologic
|
Delay
| Delay in understanding/use of sounds; use of speech error patterns that will have resolved in >90% of age-related peers based on normative data (e.g., a 6-yr-old substituting /b/ for /f/ in fish) [Dodd et al 2018] |
Disorder
| Inability to understand or correctly use sounds to convey meaning. Use of atypical (i.e., seen in <10% of population at any age) speech errors; e.g., sound preference substitution, where a favorite sound is used in place of the correct phoneme (e.g., /d/ for /k/ in cup, /d/ for /n/ in knife, and /d/ for /sh/ in shoe [Dodd et al 2018]. Phonologic disorder places a child at greater risk for literacy disorder [Foy & Mann 2012]. |
Motor
speech
disorders
|
Childhood
apraxia of
speech (CAS)
| Inability to produce sounds & syllables consistently in correct order w/clarity & correct prosody [Morgan & Günther 2017]; 3 core diagnostic CAS features (ASHA 2007):
|
Dysarthria
| Impairment of neuromuscular control & tone (e.g., spasticity, ataxia, fluctuating tone, uncoordinated & involuntary movements) → deficits across ≥1 subdomains of speech (i.e., phonation, articulation, prosody, & resonance) [Braden et al 2021] |
Stuttering
| Impairment of speech fluency characterized by repetitions (of sounds, syllables, words, &/or phrases), prolongation of sounds, & hesitations &/or blocks (i.e., when a child tries to speak but no sound comes out) [Reilly et al 2015] |
Language disorders. Children with SETBP1-HD have a mild-to-moderate expressive and receptive language disorder (Table 4). In about 30% of affected individuals, receptive language may be better than expressive language [Morgan et al 2021].
Children are typically sociable with a strong desire to communicate, yet social language is poorer than for typically developing peers.
Table 4.
Language Disorders: Definitions
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Language Disorder | Definition |
---|
Receptive language disorder
| A deficit in understanding language relative to peers. ≥1 sub-domains of language may be affected (e.g., semantics, sentence structure). |
Expressive language disorder
| A deficit in producing language relative to peers. ≥1 sub-domains of language may be affected (e.g., semantics, sentence structure). |
Intellectual Disability (ID)
The spectrum of intellectual disability (noted in 80% of individuals) ranges from mild to severe.
Children with SETBP1-HD whose intellect is in the normal or borderline range (IQ 80-90) typically were diagnosed following genetic testing for severe speech and language disorder and/or behavioral problems.
Behavioral Problems
Most commonly reported are attention/concentration deficits and hyperactivity, and impulsivity, leading in many instances to a diagnosis of ADHD. Other behavioral problems include anxiety, autism spectrum disorder (ASD), sleep disturbances, self-injury, and other aggressive behaviors. Some children have autism or autistic features and social communication disorders. While many children with SETBP1-HD are not diagnosed with ASD, many have restricted interests and sensory sensitivities that overlap with an ASD phenotype.
Additional Findings
Ophthalmologic involvement includes refractive errors, most commonly hypermetropia, and less commonly astigmatism and myopia. Strabismus is also seen.
Feeding difficulties. Poor sucking and slow feeding related to hypotonia can be evident in the neonatal period and infancy. Some children require nasogastric tube feeding. Beyond infancy and into the preschool years, some children experience problems chewing lumpy or solid foods.
Excessive drooling. Some young children have difficulty managing saliva, resulting in excessive drooling that may in turn lead to skin irritation.
Ankyloglossia (i.e., a short frenulum) is more common than in the healthy population (prevalence is 3%-5%). While a short frenulum is not related to delays in speech development, it can affect articulation and pronunciation. A short frenulum may contribute to feeding difficulties.
Cryptorchidism is noted in about 20% of males, although to date SETP1-HD has not been associated with other urogenital abnormalities.
Digestive problems include diarrhea, constipation, food allergies, reflux, and GERD.
Seizures/epilepsy. The majority of seizures (reported in ~20% of individuals) were infantile febrile seizures.
Epilepsy was reported in three individuals, all of whom had generalized seizures [Coe et al 2014, Leonardi et al 2020]. In two of three, onset was in infancy; in the third onset was at age 22 years. After epileptic seizures ceased in one child at age six years, anti-seizure medication was successfully discontinued.
Skeletal abnormalities observed in 14 individuals include bilateral hip dysplasia, abnormal vertebrae at birth, hyperkyphosis, hyperlordosis, increased lumbar lordosis, and (in 10 of the 14 individuals) slight abnormalities of the extremities including bilateral fifth finger clinodactyly, slight 2-3 syndactyly, brachydactyly, and pes cavus [Jansen et al 2021].
Subtle dysmorphic features in several individuals include ptosis, blepharophimosis, broad nasal bridge, hypertelorism, full nasal tip, and a high arched palate. See and Jansen et al [2021].
Other
The following were normal:
The possible relationship of the following findings to SETBP1-HD is unknown, given the high frequency of these findings in the general population:
Recurrent ear infections (~25% of infants)
Dry skin and/or eczema (20% of individuals)
Different types of hearing impairment (3 individuals)
Prognosis
Based on current data, life span is not shortened in SETBP1-HD, as several adults have been reported. To date, data are limited on possible progression of behavioral abnormalities and/or neurologic findings.