Evidences for an allelic variant of the human LC/CG receptor rather than agene duplication: Functional comparison of wild-type and variant receptors

Two different human LH receptor sequences have been published, differing by a six-base pair insertion encoding Leu-Gin at position 55-60. It has recen tly been proposed that this would reflect the existence of two LH receptor loci in the human genome. The present results demonstrate that both sequenc es exist as allelic variants in the Caucasian population. Allelic frequency of "LQ variant" and "wild-type" (alpha LQ) allele are 0.26 and 0.74 respec tively. In contrast, the LQ allele is virtually absent from the Japanese po pulation. Functional characterization of both alleles by transient expressi on in COS-7 cells did not reveal any difference between the two receptors, neither for cell surface expression nor for cAMP production and sensitivity to hCG/LH.