Genetic analysis of a new haplotype of the histidine decarboxylase gene complex in C57BL/6 mice

A new allele of the testosterone-responsive gene, Hdc-a, in the histidine decarboxylase gene complex of the mouse

In C57BL/10 and the majority of other strains of mice, females have about 20-fold higher kidney histidine decarboxylase levels than males; in DBA/2 mice, however, HDC in females is only 3- to 4-fold higher than males. The low ratio HDC phenotype of DBA/2 animals is due to decreased sensitivity of the HDC gene complex to repression by testosterone in males. From conventional crosses and by the use of the BXD recombinant inbred lines we conclude that the C57BL/ 10: DBA/2 difference, in testosterone sensitivity of HDC, is due to an allelic difference in the regulatory geneHdc-aof the HDC gene complex, [Hdc], on chromosome 2; DBA/2 contains a third allele of this gene,Hdc-ad.

A new regulatory gene in the histidine decarboxylase gene complex determines the responsiveness of the mouse kidney enzyme to testosterone

The level of histidine decarboxylase in mouse kidney normally differs between the sexes with females higher than males. In a strain derived from feral Danish mice (DAN), however, both males and females have the same, high, HDC activity due to the males being insensitive to repression by testosterone. Genetic analysis indicates that this insensitivity is caused by a variant allele of a new gene in the histidine decarboxylase gene complex,Hdc-a; theHdc-aballele in C57BL/10 confers high sensitivity to testosterone whereas theHdc-awallele in the DAN strain confers low sensitivity. In addition, the DAN strain has a novel haplotype for the other three known elements of [Hdc]: the alleleHdc-sdof the structural gene, theHdc-cdallele of the gene determining enzyme concentration, and the oestrogen-inducible alleleHdc-eb.