Clinical Description
CTNNB1 neurodevelopmental disorder (CTNNB1-NDD) is characterized in all individuals by mild-to-profound cognitive impairment and in some individuals by exudative vitreoretinopathy. Exudative vitreoretinopathy, observed in up to 39% of reported individuals, is often diagnosed in early childhood and may present in infancy in those with significantly compromised vision [Sun et al 2019, Coussa et al 2020]. Other common findings include truncal hypotonia, peripheral spasticity, dystonia, behavior problems, microcephaly, and refractive errors and/or strabismus. Less common features include intrauterine growth restriction, feeding difficulties, and scoliosis.
To date, at least 57 individuals have been identified with a pathogenic variant in CTNNB1 [Tucci et al 2014, Kuechler et al 2015, Dixon et al 2016, Winczewska-Wiktor et al 2016, Kharbanda et al 2017, Li et al 2017, Panagiotou et al 2017, Pipo-Deveza et al 2018, Karolak et al 2019, Sun et al 2019, Wang et al 2019, Coussa et al 2020, Jin et al 2020, Ke & Chen 2020, Rossetti et al 2021, Ho et al 2022]. The following description of the phenotypic features associated with CTNNB1-NDD is based on reports that included sufficient phenotypic information. (Note: Information on three individuals heterozygous for a pathogenic variant in a gene in addition to CTNNB1 [Karolak et al 2019, Ho et al 2022] are not included in Table 2 or in the following discussion.)
Table 2.
Select Features of CTNNB1 Neurodevelopmental Disorder
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Feature | # of Persons w/Feature / # Assessed | Comment |
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Neurodevelopmental
|
DD/ID | 57/57 (100%) | |
Speech delay | 38/39 (97.4%) | |
Motor delay | 36/36 (100%) | |
Behavior problems | Autistic features | 19/41 (46.3%) | Incl persons w/poor eye contact & stereotypies |
ADHD | 7/41 (17.1%) | |
Aggression / self-mutilation | 18/37 (48.6%) | |
Sleep disturbances | 9/26 (34.6%) | |
Truncal hypotonia | 39/47 (83%) | |
Peripheral spasticity | 43/48 (89.6%) | |
Dystonia | 8/37 (21.6%) | |
Ataxia | 10/28 (35.7%) | |
Microcephaly | 42/52 (80.8%) | |
Ophthalmologic 1
|
Exudative vitreoretinopathy | 9/23 (39.1%) | Characterized by peripheral retinal avascularity, neovascularization w/secondary fibrosis, vessel pruning, retinal folds assoc w/exudates & traction complicated by temporal dragging of macula & vessels, retinal holes, & retinal detachment |
Strabismus | 31/56 (55.4%) | |
Refractive errors 2 | 15/56 (26.8%) | Incl myopia, hypermetropia, & astigmatism |
Other
|
IUGR | 10/44 (22.7%) | |
Short stature | 8/39 (20.5%) | |
Feeding difficulties | 14/35 (40%) | |
Scoliosis | 6/30 (20%) | |
ADHD = attention-deficit/hyperactivity disorder; DD = developmental delay; ID = intellectual disability; IUGR = intrauterine growth restriction
Based on Tucci et al [2014], Kuechler et al [2015], Dixon et al [2016], Winczewska-Wiktor et al [2016], Kharbanda et al [2017], Li et al [2017], Panagiotou et al [2017], Pipo-Deveza et al [2018], Karolak et al [2019], Sun et al [2019], Wang et al [2019], Coussa et al [2020], Jin et al [2020], Ke & Chen [2020], Rossetti et al [2021], Ho et al [2022]
- 1.
- 2.
Myopia was detected in three of 56 reported individuals (5.4%) and hypermetropia in 14 of 56 reported individuals (25%).
Neurodevelopmental Features
Developmental delay (DD) and intellectual disability (ID). All reported individuals had mild-to-severe developmental delay / intellectual disability, with reported IQ scores ranging from 28 to 72, although results of formal IQ testing were not always available [Tucci et al 2014, Kuechler et al 2015, Wang et al 2019]. While the number of affected adults reported is limited, some adults with CTNNB1-NDD were able to care for themselves as well as raise children with support from other family members [Panagiotou et al 2017, Wang et al 2019, Ho et al 2022].
Regression in ability to ambulate and cognitive function was reported in some affected individuals, which may be explained by progressive peripheral spasticity and/or visual impairment [Tucci et al 2014, Kuechler et al 2015, Winczewska-Wiktor et al 2016, Kharbanda et al 2017].
Motor delay is common and may be partly attributed to central hypotonia and/or peripheral spasticity.
Speech delay is common. First words are often delayed, but some individuals speak in sentences. One affected individual remained nonverbal as an adult [Tucci et al 2014]. Some individuals had more advanced verbal comprehension when compared to expressive language skills as evidenced by their use of sign language [Tucci et al 2014, Kuechler et al 2015]. Some affected individuals had speech apraxia and dysarthria [Kuechler et al 2015, Kharbanda et al 2017, Pipo-Deveza et al 2018].
Behavior problems included inattention, hyperactivity, self-mutilation, and aggression toward others. Some affected individuals are described to be happy, friendly, and sociable, although restlessness, excessive crying, and temper tantrums have also been reported. Autistic features such as poor eye contact, frequent stereotypic movements, and restricted interests were described in some affected individuals. Sleep disturbances are common.
Truncal hypotonia, reported in the majority of individuals with CTNNB1-NDD, may be the first sign prompting medical attention.
Peripheral spasticity often progresses with age, although some affected infants may have hypertonia at birth [Kuechler et al 2015]. While some may develop a subtle increase in tone only evident upon detailed examination, others may have spasticity warranting specific management (see Management).
The lower limbs are often affected, whereas the upper limbs have milder involvement. Spinal MRI is often unremarkable, although tethered cord, syringomyelia, and lipomyelomeningocele have been reported [Kuechler et al 2015, Dixon et al 2016, Rossetti et al 2021].
Movement disorders. Dystonia, the most common reported movement disorder, can be focal or generalized [Wang et al 2019, Ho et al 2022]. Diurnal fluctuation, reported in one individual, improved with administration of levodopa [Pipo-Deveza et al 2018]. Bradykinesia, oral facial dyspraxia, apraxia of upward gaze, and choreoathetoid movements have been described on occasion [Winczewska-Wiktor et al 2016, Kharbanda et al 2017, Rossetti et al 2021].
Ataxia. Gait is occasionally described to be wide-based and ataxic, despite the lower-limb spasticity [Kuechler et al 2015, Winczewska-Wiktor et al 2016, Kharbanda et al 2017, Wang et al 2019].
Neuroimaging. While brain imaging is normal in the majority of affected individuals, structural brain anomalies include corpus callosum hypoplasia, hydrocephalus, abnormal gyration of temporal lobe, absent right fornix, hypoplastic brain stem, delayed bilateral frontal lobe myelination, arachnoid cyst, and frontal pachygyria [Kuechler et al 2015, Winczewska-Wiktor et al 2016, Jin et al 2020].
Ophthalmologic Features
Exudative vitreoretinopathy, the most distinctive ophthalmologic finding, is consistent with familial exudative vitreoretinopathy (FEVR), which is caused by incomplete retinal angiogenesis resulting in retinal ischemia. This peripheral retinal avascularity leads to increased neovascularization, which can cause fibrosis and resultant traction and retinal detachment [Dixon et al 2016].
Manifestations of FEVR can range from an incidental finding of localized peripheral retinal avascularity that does not affect vision, to total blindness resulting from tractional and exudative retinal detachments. Although the majority of individuals reported with CTNNB1-related FEVR have neovascularization, subretinal exudation, retinal folds, and retinal detachments, ascertainment bias should be taken into account [Coussa et al 2020].
Significant visual impairment was reported in 17.5% (10/57) of affected individuals; 7% (4/57) of affected individuals were legally blind [Li et al 2017, Panagiotou et al 2017, Wang et al 2019, Ke & Chen 2020, Rossetti et al 2021].
Other ophthalmologic findings commonly observed in individuals with neurodevelopmental disorders (who do not have exudative vitreoretinopathy) include strabismus and refractive errors (astigmatism, myopia, and hypermetropia).
Other Features
Growth. The majority of affected individuals were born at term; intrauterine growth restriction is common. Inadequate weight gain and postnatal short stature (height ≥2 SD below the mean) may be present without apparent feeding difficulties.
Microcephaly (head circumference ≥2 SD below the mean) is often acquired but may be present at birth. Microcephaly may progress as affected individuals age [Kuechler et al 2015]. One individual with microcephaly had craniosynostosis [Ho et al 2022].
Feeding difficulties / gastrointestinal problems. Feeding problems are common; gastrointestinal problems can include gastroesophageal reflux disease, swallowing difficulties, and oromotor dyspraxia. If not managed properly, feeding difficulties may result in aspiration and inadequate weight gain (see Management).
Musculoskeletal anomalies are in general uncommon except for scoliosis. Other findings such as pes cavus, syndactyly, flat feet, clubfoot, and polydactyly have been reported [Kuechler et al 2015, Ke & Chen 2020].
Prognosis. Based on current data, life span is not limited in individuals with CTNNB1-NDD, as several adults have been reported. The majority of these adults (age range 37-50 years) were identified by follow-up parental studies at the time of diagnosis of an affected child. Data on possible progression of behavior abnormalities or neurologic findings are limited.