A single origin of phenylketonuria in Yemenite Jews
Article Abstract:
Phenylketonuria (PKU) is a metabolic disorder that results from the accumulation of high levels of phenylalanine and its breakdown products in the blood. Phenylalanine accumulates because the enzyme that catalyzes (facilitates) its degradation, phenylalanine hydroxylase (PAH), is missing due to a genetic defect. Unless an infant with PKU consumes a low-phenylalanine diet from birth, severe mental retardation develops. The incidence of PKU is highest in Ireland and western Scotland, and among Jews from Yemen; presently, Yemenite Jews constitute 25 percent of the Jewish PKU patient population in Israel. Since Yemenite Jews existed as an isolated community for centuries, it is possible that PKU results from just one mutation in this population. This possibility was tested by examining the gene that codes for PAH among Israeli Yemenites. Twenty-two families who had at least one case of PKU underwent chromosome analysis; one defect was found to be responsible for all cases of PKU. The defect, a deletion of axon 3 on the PAH gene, was traced to 25 different locations throughout Yemen. Further demographic information revealed that two families from the capital of Yemen had been the origin of nine subsequent families. Other families were involved, but all had originated in the capital and migrated out. It is likely that a single Jewish individual with this deletion introduced it into the gene pool. The reasons for the high frequency of this defective gene among Jewish Yemenites can now be studied using this defined group of people and appropriate epidemiological studies. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1990
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Origin and diversification of endomycorrhizal fungi and coincidence with vascular land plants
Article Abstract:
The origin of endomycorrhizal fungi was traced by sequencing ribosomal DNA genes from 12 species. The existence of three families within the arbuscular fungi based on morphological characters was confirmed through phylogenetic analyses. Estimates on the origin of vesicular-arbuscular mycorrhizae (VAM) range from 353-462 million years ago, which fits in the hypothesis that VAM was useful in populating of lands by ancient plants. Approximate dates for divergence of major branches were obtained. Discovery of endomycorrhizae in angiosperms, gymnosperms and ferns worldwide bolster the hypothesis that it is of ancient origin.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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The origin of HIV-1 isolate HTLV-IIIB
Article Abstract:
Controversies of the high level of variability among HIV-1 isolates were provoked when similarities between the first two human immunodeficiency virus types 1 (HIV-1) isolates Lai/LAV and Lai/IIIB were revealed. A study was conducted to determine the presence of the type of HIV-1 variant from the HIV-1 isolates in the early stages of the AIDS epidemic. HIV-1 Lai/IIIB and HIV-1 Lai/LAV were found in an LAI patient and a sequence identical HIV-1 Lai/IIIB variant was found in the contaminated M2T-/B culture. The origin of the HIV-1 Lai/IIIB isolate was the patient LAI.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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