Skraban-Deardorff Syndrome in an Indian Child - A Very Rare Pathogenic Base Pair Deletion in WDR26 Gene

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). …