Rowett M A, Fleet M R
Jutland Park Suffolk Stud, Marrabel, South Australia.
J Hered. 1993 Jan-Feb;84(1):67-9. doi: 10.1093/oxfordjournals.jhered.a111279.
This report introduces the second form of true albinism to be documented in sheep, which appears mild enough not to cause serious undesirable side effects yet apparently effective enough to have the potential for general usage in the sheep industry. Based on the matings conducted to date, the albinism is inherited like an autosomal recessive. Histochemical tests reveal a defective melanin synthesis involving a block to the conversion of tyrosine to dopa but not the subsequent reactions that lead to melanin. The enzyme tyrosinase is a product of the C locus and catalyzes the conversion of tyrosine to dopa and the following reaction (dopa to dopaquinone). Therefore, it is proposed that the albinism arises from a gene in the C locus that encodes a defective tyrosinase. The gene is provisionally named albino marrabel, the gene symbol is cmar, and the locus allele symbol is Ccmar.
本报告介绍了绵羊中记录的第二种真正白化病形式，其表现似乎足够轻微，不会引起严重不良副作用，但显然又足够有效，有在绵羊产业广泛应用的潜力。根据迄今为止进行的交配情况，白化病像常染色体隐性性状一样遗传。组织化学测试显示黑色素合成存在缺陷，涉及酪氨酸向多巴转化的阻断，但不影响导致黑色素生成的后续反应。酪氨酸酶是C位点的产物，催化酪氨酸向多巴的转化以及后续反应（多巴向多巴醌）。因此，有人提出白化病源于C位点上一个编码缺陷型酪氨酸酶的基因。该基因暂命名为白化病马拉贝尔，基因符号为cmar，位点等位基因符号为Ccmar。
