Confirmation of association between D10S583 and Alzheimer's disease in a case--control sample.

Several independent studies have reported that loci on chromosome 10 are associated/linked with Alzheimer's disease (AD), including a family-based study demonstrating an association between the marker D10S583 and AD. We have examined the D10S583 polymorphic marker and apolipoprotein E (APOE) gene in a case-control study. We observed the expected association of the APOE allele varepsilon4 with AD, and an inverse association between the D10S583 allele 209 and AD. These data support the original findings that suggest the presence of a candidate gene for AD in this region of chromosome 10. The nearby insulin degrading enzyme gene has been previously proposed as a candidate gene; however, a number of other putative candidate genes are also located in this region. The ongoing investigation of the genetic source of association and linkage in this region is clearly warranted.

Mutations in PDX1, the human lipoyl-containing component X of the pyruvate dehydrogenase-complex gene on chromosome 11p1, in congenital lactic acidosis.

We have identified and sequenced a cDNA that encodes an apparent human orthologue of a yeast protein-X component (ScPDX1) of pyruvate dehydrogenase multienzyme complexes. The new human cDNA that has been referred to as "HsPDX1" cDNA was cloned by use of the "database cloning" strategy and had a 1,506-bp open reading frame. The amino acid sequence of the protein encoded by the cDNA was 20% identical with that encoded by the yeast PDX1 gene and 40% identical with that encoded by the lipoate acetyltransferase component of the pyruvate dehydrogenase and included a lipoyl-bearing domain that is conserved in some dehydrogenase enzyme complexes. Northern blot analysis demonstrated that the major HsPDX1 mRNA was 2.5 kb in length and was expressed mainly in human skeletal and cardiac muscles but was also present, at low levels, in other tissues. FISH analysis performed with a P1-derived artificial chromosome (PAC)-containing HsPDX1 gene sublocalized the gene to 11p1.3. Molecular investigation of PDX1 deficiency in four patients with neonatal lactic acidemias revealed mutations 78del85 and 965del59 in a homozygous state, and one other patient had no PDX1 mRNA expression.