The broad aim of this research is to better understand the pathogenesis and molecular biology of neurogenetic disorders which involve aberrant trace metal and/or catecholamine metabolism, with a view toward improved diagnosis and treatment of these conditions. Menkes disease, an X- linked neurodegenerative disorder of copper transport caused by defects in a gene encoding a P-type ATPase (ATP7A) and its murine homologs, continues as a particular focus. Through our mouse protocol (734-96) we delineated an abnormal plasma catechol profile in the blotchy mutant mouse based on elevated ratios of DOPAC:DHPG relative to normal littermates and to the pewter mutant allele. (The latter mutant shows only fur pigment abnormalities and no neurological symptoms.) We plan to extend these studies to other alleles at this locus, specifically the Jax-brindled. In this latter allele, we identified a novel 3 base deletion via RT-PCR of brain mRNA and cDNA sequencing, and are continuing to characterize the defect. In the human protocol (90-N-0149), through which early copper replacement is made available to Menkes disease infants identified before symptoms are present, three new patients were enrolled in '96-97. This brings to 11 the total number of very early treated Menkes patients at the NIH, which is easily the largest world experience. The availability of plasma catecholamine analysis in CNB as a rapid and reliable early diagnostic test is largely responsible for our success in patient accrual. Mutation analyses for this cohort are progressing rapidly due to recently published information about the Menkes genomic organization and sequence, and utilization of the NINDS Sequencing Facility. We have carefully characterized a novel mutation (A1362D) in 2 brothers from Trinidad, neither of whom ever received copper treatment but who show marked differences in neurological and cerebrospinal fluid neurochemical phenotypes. Copper transport assays in cultured fibroblasts were abnormal in both but did not distinguish between them. Analysis of 32 single fibroblast clones from the mildly affected sibling did not indicate mosaicism in this tissue. The disparate clinical outcomes in this family suggest that genetic and/or environmental factors may be important phenotypic modifiers, and have implications for interpreting response to early copper therapy in other Menkes disease patients. The gene for hereditary hemochromatosis, an autosomal recessive disorder of iron transport with multiorgan effects, was cloned in August 1996. To test the hypothesis that patients with severe liver disease have higher incidence of heterozygosity for the common Hfe mutation (Cys282Tyr), we analyzed Hfe in 92 liver transplant recipients with Wilson disease, alcoholic cirrhosis, cryptogenic cirrhosis, primary biliary cirrhosis (PBC), or primary sclerosing cholangitis. We found a statistically higher frequency of the mutant allele in the PBC subgroup, including 1 individual who lacked iron overload but was homozygous for the mutation, suggesting a possible role of the Hfe gene product in autoimmune processes. Because this work was peripheral to our major interests and was conducted by Rosita Kirshman, an NHGRI medical staff fellow who recently left the NIH, further work in this area will not be emphasized.
