A Rare Cause of Development Delay

Background: Tay-Sachs disease is a neurodegenerative lysosomal disorder with an autosomal recessive inheritance pattern caused by HEXA gene mutations. Children with this disease appear healthy at birth and psychomotor development proceeds normally during the first months of life. Slow neurological and development decline starts around 6 months.

Clinical Case: The authors present an eighteen-month old girl, of non-consanguineous parents, born of a full term bi-chorionic, bi-amniotic twin pregnancy, adequate somatometry at birth, with development delay noticed at the age of 6 months.

We saw her at 18 months at our referral clinic. We identified eating difficulties, motor delay (unable to stand alone), poor visual contact, poor social interaction, no verbal language and an abnormal acoustic-motor response (startle). Mother refers loss of previously acquired skills (hand clapping). On examination we also detected an abnormal posture with neck extension, hypotonia, ataxia, brisk reflexes, optic nerve atrophy and macular cherry red spot bilaterally. No other system anomalies detected. Cranial MRI and EEG were normal. A Gangliosidoses was suspected, so we requested lysosomal biochemical study and deficit of beta-hexosaminidase A was identified, compatible with GM2-Gangliosidoses – Tay-Sachs Disease. Genetic testing confirmed the diagnosis.

Conclusion: Gangliosidoses are rare diseases, at this moment without specific treatment, but its diagnosis is important for genetic counselling. A high level of suspicion is essential. The presence of a startle response and /or a cherry red spot should alert for these diseases.