Analyses of gene mutations of luteinizing hormone receptor in animals with crptorchidism and development of methods of genetic diagnosis.

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In this research project, we determined cDNA sequences of luteinizing hormone (LH) receptors derived from canine testis. Also, we analyzed the sequences of LH receptors gene in dogs and bulls with cryptorchidism, as compared with normal animals.From total RNA exctraced from normal male dogs, 2123 bp of LH receptor cDNA, except a partial sequence of 5' region, was cloned. In these process, we found a splice variant of the receptor mRNA which shows a deletion of 25 amino acids in the extracellular region. The canine LH receptor cDNA up to the terminator codon shows homologies with porcine, bovine and human sequences of 91.9%, 91.7% and 90.3%, respectively.Total RNA or genomic DNA was extracted from testicular tissues or blood sample of normal (n=46) male and cryptorchid (n=45) dogs, and normal (n=3) and cryptorchid (n=9) bulls. Partial sequences of the LH receptor gene were amplified with RT-PCR or PCR and compared between normal and affected animals.Both of the 1137^<th> and 1194^<th> b … More ases of the canine LH receptor show single nucleotide polymorphisms (SNP) with C, T or C/T for 1137^<th> base and A, G or A/G for 1194^<th> base. There were no different ratios of each SNP in both bases between normal and cryptorchid dogs. However, the ratio of A at the 1194^<th> base in the cryptorchid dogs with testicular retention in the abdoman was significantly lower than that of normal dogs and cryptorchid dogs with retention at the inguinal region. There were 6 haplotypes for 1137^<th> and 1194^<th> bases with T-G, C-A, C-G, T/C-A/G, T/C-G or C-A/G. The C-A type in the cryptorchid dogs with testicular retention in the abdoman was significantly lower than that of normal dogs and cryptorchid dogs with retention at the inguinal region. The 703^<th> base of the bovine LH receptor gene shows SNP (A (Lys), C (Gin) or A/C (Lys/Gin) ). However, there were no marked different ratios of each SNP between normal and cryptorchid dogs.We successfully cloned 2123 bp of cDNA of the canine LH receptor, except partial 5' region from testicular tissues. It is evident, in the present study, that a new type of splicing variant of LH receptor mRNA, which has not been reported in other species, is expressed in canine testis. These studies also suggest that, in crpyorchid dogs with abdominal retention, SNP patterns of the two bases (1137^<th> and 1194^<th>) in the transmembrane region may differ compared with normal and affected animals with inguinal retention. Less