Wiedemar Natalie, Drögemüller Cord
Institute of Genetics, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Anim Genet. 2014 Dec;45(6):868-70. doi: 10.1111/age.12213. Epub 2014 Sep 9.
Mutations in MITF lead to a large variety of phenotypes in human, mice and other species. They mostly affect pigmentation and hearing, whereas in mice, they may additionally cause microphthalmia and osteopetrosis. In this study, we report a single case of a Holstein calf with lack of pigmentation and microphthalmia born to healthy parents. Mendelian analysis of high-density SNP genotypes reveals a large number of parentage errors showing missing paternal alleles in the offspring, indicating a deletion encompassing 19 Mb on BTA 22. The genomic deletion affects the paternal allele and includes MITF and 131 other annotated genes. As the calf shows only one copy of the BTA 22 segment, the observed phenotype is probably caused by haploinsufficiency of the genes in that genomic region. Both the observed lack of skin pigmentation and reduced eye size can most likely be explained by a lack of MITF function.
MITF基因的突变在人类、小鼠和其他物种中会导致多种表型。这些突变大多影响色素沉着和听力，而在小鼠中，它们还可能导致小眼症和骨质石化。在本研究中，我们报告了一例荷斯坦犊牛的病例，该犊牛出生时无色素沉着且患有小眼症，其父母均健康。对高密度SNP基因型的孟德尔分析显示，存在大量亲权错误，即后代中出现父本等位基因缺失的情况，这表明牛22号染色体上存在一个19 Mb的缺失。该基因组缺失影响父本等位基因，包括MITF基因和其他131个注释基因。由于这头犊牛仅显示牛22号染色体片段的一个拷贝，观察到的表型可能是由该基因组区域中基因的单倍剂量不足引起的。观察到的皮肤色素沉着缺乏和眼睛尺寸减小很可能都可以用MITF功能缺失来解释。
