Monoallelic variants in KCNB2 gene cause a neurodevelopmental syndrome.
All individuals reported (n=7) with KCNB2 variants exhibit developmental delay. These include:
• Global developmental delay
• Speech and language delay
• Delayed motor milestones
• Cognitive delay
Other clinical characteristics include:
• Intellectual disability (5/7 patients) ranging from moderate to severe
• Mild autistic features (3/7 patients)
• Epilepsy (2/7 patients)
• Other neurological disorders such as hypotonia (2/7), regression (1/7), and ADHD (1/7)
• Different facial and limb dysmorphisms (6/7) ranging from nail hypoplasia, synophrys, macrocephaly, broad forehead, clinodactyly, beaked nose, flat mid face, frontal bossing, full lower lip, tongue protrusion and high palate.
• Ophthalmological anomalies (4/7) ranging from cortical vision impairment, Duane syndrome, hyperopia, astigmatism, cataracts, delayed visual maturation, myopia, or severe strabismus.
• Heart anomalies (2/7), with one patient with aortic dilation and the other with an abnormal trabeculation of the left ventricular myocardium.
• Genitourinary malformation (2/7) with one with a neurogenic bladder and the other with a suggestion of a slight shawl scrotum.
• Diabetes, gingival fibromatosis, low bone density, and oropharyngeal dysphagia (1/7).
KCNB2