Meckel-Gruber syndrome: A case report

Meckel–Gruber syndrome (MGS) is a rare, lethal, autosomal recessive ciliopathy characterized classically by a triad of central nervous system malformations, postaxial polydactyly, and renal cystic dysplasia. The condition is associated with a poor prognosis, and early antenatal diagnosis plays a crucial role in parental counseling and pregnancy management. However, considerable phenotypic variability exists, and incomplete expression of the classical triad has been reported in a minority of cases. We report a case of MGS with an atypical presentation. A term male neonate was born to a 21-year-old mother from a non-consanguineous marriage. First- and early second-trimester antenatal ultrasonography scans were reported as normal. A third-trimester ultrasound revealed abnormalities suggestive of a congenital malformation. At birth, the neonate was noted to have an occipital encephalocele and postaxial polydactyly. Notably, renal involvement was absent, which is an uncommon finding in MGS. The diagnosis was established based on characteristic clinical features and imaging findings. This case highlights the phenotypic variability of MGS and emphasizes that absence of renal cystic dysplasia does not exclude the diagnosis. It also underlines the importance of detailed and serial antenatal imaging, particularly in pregnancies without early ultrasound abnormalities. Given the autosomal recessive inheritance pattern of MGS and a recurrence risk of 25% in subsequent pregnancies, early diagnosis is essential for appropriate genetic counseling and informed decision-making. Reporting such atypical presentations expands the existing knowledge of the clinical spectrum of MGS and reinforces the need for heightened clinical suspicion even when all components of the classical triad are not present.