Genes on chromosomes 1 and 13 have significant effects on Ascaris infection.
Nematode parasites show a characteristic aggregated distribution among hosts. This observation has important implications for pathogenesis, immunology, and control of these infections, but the relative roles of environment and genetics in determining these patterns have remained uncertain. This paper presents the results of the first genome scan for susceptibility to infection with roundworm (Ascaris lumbricoides). Data on 375 genetic markers were generated for each of 444 members of a genetically isolated Nepalese population, the Jirels. Ascaris worm burden as assessed by egg counts was measured in these same individuals by using the Kato Katz thick smear method. The extensive genealogical data available for the population allowed assignment of all 444 individuals to a single pedigree that contained 6,209 pairs of relatives that were informative for genetic analysis. A variance components linkage analysis resulted in the unequivocal localization of two genes (one on chromosome 1 and another on chromosome 13) with clear, significant effects on susceptibility to Ascaris infection. This is the first evidence that individual quantitative trait loci influence variation in Ascaris burden in humans.
Williams-Blangero
Sarah
S
Department of Genetics, Southwest Foundation for Biomedical Research, P.O. Box 760549, San Antonio, TX 78245, USA. sarah@darwin.sfbr.org
VandeBerg
John L
JL
Subedi
Janardan
J
Aivaliotis
Mary Jo
MJ
Rai
Dev Raj
DR
Upadhayay
Ram Prasad
RP
Jha
Bharat
B
Blangero
John
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D001196:Ascariasis / Q000453:epidemiology / Q000235:genetics*; D001200:Ascaris / Q000472:pathogenicity*; D002648:Child; D002675:Child, Preschool; D002878:Chromosomes, Human, Pair 1; D002882:Chromosomes, Human, Pair 13; D008040:Genetic Linkage; D020022:Genetic Predisposition to Disease; D015894:Genome, Human; D006801:Humans; D008126:Lod Score; D008875:Middle Aged; D009390:Nepal / Q000453:epidemiology; D010270:Parasite Egg Count; D010375:Pedigree; D015995:Prevalence