Tectocerebellar dysraphia with occipital encephalocele: a phenotypic variant of the TMEM231 gene mutation induced Joubert syndrome.

There are few reported cases of tectocerebellar dysraphia with occipital encephalocele (TCD-OE) in the literature. This malformation was first described by Padget and Lindburg in 1972 and consists of an occipital encephalocele, a cerebellar midline defect, inverted cerebellum, and deformity of the tectum. Occurrence is believed to be sporadic with a male predominance and a usually poor prognosis. We report a patient with brain MRI findings compatible with tectocerebellar dysraphia and occipital encephalocele. Additional features consistent with Joubert syndrome including deepened interpeduncular fossa, as well as elongated, thickened, and anteroposteriorly oriented superior cerebellar peduncles, were noted. The patient's evaluation also revealed a homozygous mutation of the TMEM231 gene, known to cause Meckel-Gruber and Joubert syndromes. Our case represents the first reported genetic confirmation that tectocerebellar dysraphia with occipital encephalocele is not a distinct nosological entity but likely a phenotypic variation of Joubert syndrome.