To the Editor: An 8-y-old boy, second born to non-consanguineous parents with normal perinatal period, presented with global developmental delay, followed by neuroregression in motor, language, and social domains since seven years of age. He also had history of hearing loss since early childhood and right focal seizures for two months. There was no significant family history. On examination, he had hypotonia, natal teeth, short stature, and genu recurvatum. Ophthalmological examination revealed left parafoveal scar and mild tortuous dilated vessels. Electroencephalogram (EEG) revealed asymmetrical frontal discharges (right>left), suggestive of electrical status epilepticus. Brainstem evoked response audiometry (BERA) was suggestive of sensorineural hearing loss. Neuroimaging revealed significant cerebral and cerebellar atrophy with periventricular white matter T2 hyperintensities. Magnetic resonance spectroscopy (MRS) was normal. Differentials considered were progressive myoclonus epilepsy, mitochondrial disorders, Lafora disease, and neuronal ceroid lipofuscinoses. Genetic testing revealed pathogenic heterozygous base pair deletion c.905_909del (p.Gln302LeufsTer36) in exon 3 of WDR26 gene (chr1:g.224431495_224431499del) resulting in frameshift and premature truncation, suggestive of Skraban-Deardorff syndrome (SKDEAS).

SKDEAS (MIM#617616), an autosomal dominant disorder, is due to heterozygous mutations in WDR26 gene (MIM*617424) at chromosome 1q42.11-q42.12, first described by American Geneticists, Cara Skraban and Matthew Deardorff in 2017 [1, 2]. SKDEAS is characterized by developmental delay (predominantly language), intellectual disability, autism, hypotonia, characteristic coarse facies, seizures, skeletal manifestations, dysphagia, and happy/friendly personality [2,3,4]. To date, only 26 cases of SKDEAS have been reported [2,3,4]. The dysmorphism reported includes arched eyebrows, flattened/depressed nasal bridge, anteverted nares, prominent maxilla, protruding upper lip, widely spaced teeth, and abnormal gums [2,3,4]. Seizure phenotypes reported are generalized motor and non-motor absence seizures [3]. Thinning of corpus callosum, ventriculomegaly, polymicrogyria, pineal cyst, subependymal cyst, and white matter volume loss are commonly reported neuroimaging features [2,3,4]. The index child has a novel phenotype of genu recurvatum and cerebral and cerebellar atrophy in neuroimaging.