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

The histidine decarboxylase (HDC) gene complex, [Hdc], comprises the structural gene for mouse kidney HDC and closely linked regulatory elements which determine enzyme concentration and its response to hormones. One of these regulatory elements, Hdc-e, determines the response (induction or repression) of kidney HDC to oestrogen. HDC is oestrogen-inducible in C57BL/10 and oestrogen-repressible in DBA/2 and C57BL/6; alleles of Hdc-e segregate in crosses between C57BL/1O and DBA/2 and between the C57BL substrains. Two different haplotypes of [Hdc] have been defined previously, B.10 (Hdc-s», Hdc-c, Hdc-e") in C57BL/10 and D (Hdc-!?, Hdc-c, Hdc-e) in DBA/2. C57BL/6 represents a third haplotype (B.6) (Hdc-s», Hdc-c", Hdc-e*) which differs from both B.10 and D. Hdc-e may therefore be a component of the complex independent of Hdc-s and Hdc-c.