Genomic distribution and gonadal mRNA expression of two human luteinizing hormone receptor exon 1 sequences in random populations

Exon 1 of the human luteinizing hormone receptor (LHR) gene coding region e xhibits at least two forms of sequence heterogeneity between 37 and 60 bp, spanning the junction of the signal peptide and the amino terminus of the m ature protein. The LHR 1 differs from the LHR 2 by the insertion of 6 bp in exon 1 but is of identical sequence in the 5' flanking region. RFLP analys is of the two haplotypes within a random population of 63 individuals revea led allele frequencies of 0.37 and 0.63 for LHR 1 and LHR 2, respectively. 94% of the samples contained at least one LHR 2 allele, whereas only 68% co ntained the LHR 1 allele. No gender differences were observed, and both hom ozygotes and heterozygotes displayed apparently normal reproduction. Revers e-transcriptase polymerase chain-reaction analyses of LHR mRNA from testes and ovaries revealed that both haplotypes are transcribed in normal individ uals, with no difference in tissue specific distribution, Thus, at least tw o functional polymorphic forms of exon 1 coding region of the same LHR gene are present in a random human population.