Microvillous Inclusion Disease (MID) is a rare, autosomal recessive gastrointestinal disease of increased frequency among the Navajos. Previous work has shown a deficiency of RAB8 in one Japanese patient, while homozygous mutations in MYO5B were found in 7 of 10 mostly Middle Eastern families. We have identified a shared homozygous mutation in MYO5B in seven affected Navajos with the expected heterozygosity in five parents. We have developed a simple restriction enzyme based assay that allows for rapid screening for this mutation.

There is abundant evidence that cholesterol metabolism, especially as mediated by the intercellular transporter APOE, is involved in the pathogenesis of sporadic, late-onset Alzheimer disease (SLAD). Identification of other genes involved in SLAD pathogenesis has been hampered since gene association studies, whether individual or genome-wide, experience difficulty in finding appropriate controls in as much as 25% or more of normal adults will develop SLAD. Using 152 centenarians as additional controls and 120 “regular,” 65- to 75-year-old controls, we show an association of genetic variation in NPC1 with SLAD and/or aging. In this preliminary study, we find gradients of two non-synonymous SNP’s allele frequencies in NPC1 from centenarians through normal controls to SLAD in this non-stratified Polish population. An intervening intronic SNP is not in Hardy-Weinberg equilibria and differs between centenarians and controls/SLAD. Haplotypes frequencies determined by fastPHASE were somewhat different, and the predicted genotype frequencies were very different between the 3 groups. These findings can also be interpreted as indicating a role for NPC1 in aging, a role also suggested by NPC1’s role in Dauer formation (hibernation, a longevity state) in C. elegans.