Search

To determine whether nonclassical steroid 21-hydroxylase deficiency in Japan has the same molecular basis as in western countries, we have characterized the mutations of the CYP21 gene in 7 Japanese patients with nonclassical (NC) steroid 21-hydroxylase deficiency. In the Japanese NC cases the P30L was present in one allele in 5 of the 7 patients and on both alleles in one patient. By contrast, the V281L mutation, which was present in about 60% of NC cases in western countries, was not identified in any patient. Among our 7 cases, 4 were detected through neonatal mass screening by a mild increase in serum 17-hydroxyprogesterone (without any symptoms of CAH) at birth, but the 2 cases who were diagnosed as adults were born before nationwide neonatal screening was instituted, so that the Japanese neonatal screening program does detect some cases of NC steroid 21-hydroxylase deficiency. We suggest that P30L mutation is more frequent in Japanese NC CAH than V281L and that the frequency of the mutations causing NC steroid 21-hydroxylase deficiency in Japan might be different from that in western countries.

We describe a Japanese patient with male-limited precocious puberty who has a heterozygous thymine to cytosine (T to C) transition at nucleotide 1193; the mutation encodes a methionine to threonine substitution in residue 398 (M398T) of transmembrane helix 2 of the luteinizing hormone/choriogonadotropin receptor. Transfected into COS-7 cells, M398T exhibited constitutively high basal cAMP levels but retained an agonist-induced cAMP response. The constitutively higher cAMP levels caused by M398T are consistent with Leydig cell activation and precocious puberty in the patient. By comparison to wild type receptor, M398T transfectants have significantly lower agonist-induced inositol phosphate (IP) levels at > 10(-10) M hCG concentrations and a higher apparent affinity for binding hCG. These data suggest that the M398T substitution alters Gq coupling and phospholipase-C activation, as well as Gs, coupling and adenylyl cyclase activity, and changes the conformation of the extracellular domain of the receptor.

Familial male-limited precocious puberty (FMPP) is an autosomal dominant disorder characterized by marked elevation of serum testosterone despite low levels of gonadotropin. Recently, a single point mutation in the LH/hCG receptor (LH/CGR) gene was found in FMPP families that constitutively activates the LH/CGR, causing Leydig cell activation and precocious puberty. Among the Japanese population, only four sporadic cases of male-limited precocious puberty have been reported. In the current study, we examined one of the four reported Japanese patients with sporadic male-limited precocious puberty and found the same mutation as that in the FMPP families. Genomic DNA was isolated, and the polymerase chain reaction (PCR) was performed to amplify a fragment of LH/CGR DNA encoding amino acid residues that include transmembrane helixes 5 and 6. Sequencing of the PCR products revealed a heterozygous adenosine-guanine transition at nucleotide 1733 in codon 578. The mutation encodes an aspartic acid578-glycine substitution in transmembrane helix 6. The mutant LH/CGR, created by site-directed mutagenesis in vitro, exhibited constitutively higher cAMP levels in transfected COS-7 cells than the wild-type LH/CGR, as described previously; however, basal inositol phosphate levels were not increased by transfection with complementary DNA for the mutant receptor. The concentration and affinity of [125I]hCG-binding sites were similar in cells transfected with the mutant and wild-type LH/CGR complementary DNAs, indicating that the mutant did not alter the production of receptor or its ability to bind human LH/CG. The sporadic occurrence of this case was confirmed by further studies. The mutation creates a recognition site for the restriction endonuclease MspI. Restriction digestion was positive for the mutant not digested by MspI, indicating that the patient's mutant allele was not inherited from his parents. DNA analysis of the patient and the parents, using microsatellite repeat markers, was compatible with biological paternity and maternity. We conclude that the aspartic acid578-->glycine mutation in the LH/CGR has arisen in the Japanese population and is the cause of a sporadic case of male-limited precocious puberty.