THE IMPACT OF THE ENZYME STEROID 5α-REDUCTASE 2 DEFICIENCY ON UROGENITAL BIRTH DEFECT IN MALES

Livia-Irina Olaru

Abstract


This research work on 5α-reductase 2 is aiming to put into evidence how a mutation of the gene codifying for this enzyme can affect the phenotype of different males, leading at a partial female phenotype.  This type of research focuses on offering a scientific explanation on different health problems affecting the normal lives of some people, even from early stages of their evolution.

The experiment is focused on studying the impact of an enzyme called “steroid 5α-reductase” on the development of male urogenital components during the embryological life.  In order to study the steroid 5α-reductase 2 activity, the following procedures were used: isolation of a 5α-reductase 2 gene, genomicDNAisolation, and polymerase chain reactions.

Biochemical analysis put into evidence two mutations representing opposite poles of disease manifestation, i.e. feminization of external genitalia versus predominantly male development. It suggested a correlation between clinical expression and severity of the impairment of enzyme function.  As mentioned by Imperato-McGinley, Guerrero, Gautier, & Peterson (1974), one of the mutations is called “G196S mutation.”  This mutation consists of a serine substitution for a glycine at position 196.  In this case, the level of 5α-reductase activity was sufficient to induce partial virilization.  The second type of mutation is called “G34R mutation.”  This mutation consists of an arginine substitution for glycine at position 34.  The G34R enzyme is essentially inactive, thus giving rise to the female phenotype.

Mutations in the type 2 gene are responsible for autosomal recessive genetic disease of 5α-reductase deficiency.


Keywords


conversion of testosterone, dihydrotestosterone, virilization, mammals, G196S mutation, G34R mutation, steroid 5α-reductase

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References


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DOI: http://dx.doi.org/10.12955/cbup.v2.473

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