A 5 years old girl with swallowing difficulty, recurrent chest infections and developmental delay. She can only say 4 words. Her parents are first-degree cousins, and there is no family history of a similar condition. Her growth parameters at 5 years of age were weight 9.4 kg, height 82.5 cm and head circumference 46 cm, all below the 3rd percentile. Her physical examination was significant for a blue sclera, hypotonia and hyporeflexia. Vision and hearing were normal, and other examinations were within normal limits. The brain MRI was grossly normal with diffuse T-2 hyperintensity in subcortical white matter. 