Homozygosity for Non-H1069Q Missense Mutations in ATP7B Gene and Early Severe Liver Disease: Report of Two Families and a Meta-analysis.

Most patients with Wilson's disease (WD) are compound heterozygote, which complicates establishing genotype-phenotype correlations. We identified five patients who presented with early and/or severe hepatic disease who are homozygous for W939C missense mutation on exon 12 of ATP7B. We therefore conducted a meta-analysis to determine the phenotype of patients homozygous for missense or nonsense mutations in all ATP7B exons.The meta-analysis showed that 69% and 31% of patients are homozygous for H1069Q and non-H1069Q mutations, respectively. Compared to patients with H1069Q, those with non-H1069Q mutations were significantly more likely to have a hepatic phenotype, severe liver disease, a mixed phenotype, and less likely to have a neurologic phenotype. Compared to patients with nonsense mutations, those with non-H1069Q ones were equally likely to present with a hepatic phenotype and to have severe liver disease. Mean age at symptom onset in the non-H1069Q versus the H1069Q group was 15.5 versus 20.5years (p<0.001).Our data suggest that mutation W939C and other non-H1069Q missense mutations are associated with early disease onset, a hepatic phenotype, and a high risk of hepatic failure in homozygous patients. Early identification of such patients by genetic screening is important for timely initiation of treatment and prevention of complications.

Cardiac involvement in nonketotic hyperglycinemia.

Nonketotic hyperglycinemia is an autosomal recessive disorder of glycine metabolism characterized by the accumulation of glycine in the serum and cerebrospinal fluid with elevated cerebrospinal fluid to serum glycine ratio. The disease primarily affects the central nervous system, and has not been previously associated with myocardial involvement. In this article, the authors report an infant with nonketotic hyperglycinemia, who was found to have progressive left ventricular hypertrophy and dysfunction. His older sibling, who had a similar neurologic presentation, died of dilated cardiomyopathy as stated by the parents. The authors speculate that glycine may have a role in the development of cardiac dysfunction. The incidence of cardiac involvement may be under-diagnosed. They suggest the need for a cardiac evaluation in confirmed cases of nonketotic hyperglycinemia.