Steroid 5 alpha-reductase two genes/two enzymes

Formula (1) compounds then are dissolved in a suitable organic solvent, preferably THF, and cooled to -20° C. to 0° C., and a fluorinating agent such as hydrogen fluoride, or, preferably, pyridinium poly(hydrogen fluoride) is added to yield formula (m) compounds in which X is fluoro. Formula (m) compounds are dissolved in a suitable organic solvent such as THF followed by addition to a solution of a metalloamide base such as lithium diisopropylamide or, preferably lithium bis(trimethylsilyl)amide in a suitable organic solvent such as THF. To this reaction mixture then is added a triflating agent such s trifluoromethanesulfonic anhydride, or, preferably, N-phenyltrifluoromethanesulfonimide to yield formula (o) compounds.

Can et al. (1998) studied the molecular genetics of a large isolated inbred Turkish kindred with male pseudohermaphroditism (PPSH; 264600 ) due to either 5-alpha-reductase-2 (SRD5A2) or 17-beta hydroxysteroid dehydrogenase-3 (HSD17B3; 605573 ) gene defects. Using SSCP analysis and DNA sequencing, a new mutation in exon 5 of the SRD5A2 gene was detected in some male pseudohermaphrodites from this kindred. This single base (adenine) deletion caused a frameshift at amino acid position 251, resulting in the addition of 23 amino acids at the C terminus of this 254-amino acid isozyme. Expression of the mutant isozyme in CV1 cells showed a complete loss of enzymatic activity in the conversion of [14C]testosterone to dihydrotestosterone, without a change in the mRNA level compared to that of the wildtype isozyme. Analysis of the HSD17B3 gene in other male pseudohermaphrodites from this kindred revealed a G-to-A transition at the boundary between intron 8 and exon 9, disrupting the splice acceptor site of exon 9 ( ). In addition to finding male pseudohermaphrodites with either a homozygous SRD5A2 or HSD17B3 gene defect in this kindred, other affected males were found to be genetically more complex, ., homozygous for the SRD5A2 defect and heterozygous for the HSD17B3 defect, or homozygous for the HSD17B3 defect and heterozygous for the SRD5A2 defect. Also, phenotypically normal carriers were identified with either one or both gene defects. Homozygous male pseudohermaphrodites with SRD5A2 or HSD17B3 gene defects were phenotypically distinguishable by the presence of mild gynecomastia in the latter. Hormone data were consistent with the particular homozygous gene defect. The authors concluded that 2 gene defects, one in SRD5A2 and the other in HSD17B3, can each cause male pseudohermaphroditism in a large isolated Turkish kindred, and that the 2 defects segregate independently and can be inherited from 2 different progenitors. They stated that the analysis of a new mutation in exon 5 of the SRD5A2 gene supported the functional importance of the C terminus of the SRD5A2 isozyme.

Micropenis refers to an extremely small penis with a stretched penile length of less than SD below the mean for age or stage of sexual development. It should be differentiated from a buried or hidden penis and aphallia. It is important to use a standard technique of stretched penile measurement and nomograms for age to identify children with micropenis. All children above 1 year of age with a stretched penile length of less than cm need evaluation. Based on etiology they can be classified as hypogonadotropic hypogonadism (hypothalamic or pituitary failure), hypergonadotropic hypogonadism (testicular failure), partial androgen insensitivity syndrome and idiopathic groups. The help of a pediatric endocrinologist, geneticist, pediatric surgeon and/or urologist is often necessary. Growth velocity is an important determinant of associated hypothalamic or pituitary pathology. GnRH and/or hCG stimulation tests are often helpful in evaluating the etiology. Similarly chromosomal studies are indicated in a few. Often the diagnosis is inferred by the presence of clinical features suggestive of a syndrome usually associated with hypogonadotropic hypogonadism. Irrespective of the underlying cause a short course of testosterone should be tried in patients with micropenis and an assessment of the penis to respond should be made. Transdermal DHT has also been reported to be effective in prepubertal children. Children with hypopituitarism and GH deficiency respond to appropriate hormonal therapy. Surgical correction is not indicated in the common endocrine types of micropenis. Many studies have shown that most testosterone treated children have satisfactory gain in length of penis and sexual function. Thus sexual reassignment is done very infrequently now.

Steroid 5 alpha-reductase two genes/two enzymes

steroid 5 alpha-reductase two genes/two enzymes

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