HD research has directly benefitted from the application of recombinant DNA technology to genetic linkage analysis. Using two HinD3 restriction fragment length polymorphisms (RFLPs) generated from the same genomic clone (G8) on chromosome 4 (CH4), found a significant linkage (maximum recombination fraction (Θ) = 0.0, z=8.53) in two large HD families. The level of heterozygosity at the G8 locus was determined to be 57%. The G8 sequence was originally mapped to CH4 by Southern blot analysis of human-mouse somatic cell hybrids. Using somatic cell hybrids with a translocated portion of CH4, it has been possible to further localize G8 on CH4 placing G8 at pter-q12. Recent evidence indicates that G8 is absent in Wolf's syndrome in which the pter-14 region of CH4 is deleted. This information suggests that G8, and thus the HD gene, is located on the distal portion of the short arm of CH4. Since the publication of this HD linkage study, two subclones (PK082, PK083) of G8 and an overlapping genomic clone (R7) have been developed. In addition to HinD3, other polymorphisms have been established for the enzymes Pst1, Bgl1, EcoR1, PVU and NCI2. The level of heterozygosity using the HinD3 and EcoR1 polymorphisms is 86%. When the Bgl1 and Pst1 markers are added, the level of heterozygosity is increased to 92%. At the present time, no crossovers have been observed between the RFLPs, lending support to the hypothesis that they are very tightly linked and will almost always be inherited as an intact haplotype.
|Original language||English (US)|
|Number of pages||4|
|Journal||Genetic epidemiology. Supplement|
|State||Published - Dec 1 1986|
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