Pulmonary hypertension associated with nonketotic hyperglycinaemia

Nonketotic hyperglycinaemia (NKH) is an autosomal recessive disorder characterized by defective glycine degradation by the mitochondrial glycine cleavage system. The clinical features include lethargy, hypotonia, apnoea, seizures and severe psychomotor retardation, all attributed to the accumulation of glycine in the nervous system. Pulmonary hypertension (PHN) has not been reported in NKH. We describe four patients with NKH who had PHN in addition to the characteristic manifestations of NKH. This newly recognized association might provide additional insight into the underlying pathophysiology of PHN.