Hasegawa Kiyotoshi, Sasaki Shinji, Sakamoto Yoichi, Takano Akifumi, Takayama Megumi, Higashi Tomoko, Sugimoto Yoshikazu, Yasuda Yasuaki
Shimane Prefecture Livestock Technology Center, Koshi, Izumo, Shimane, Japan.
Shirakawa Institute of Animal Genetics, Japan Livestock Technology Association, Odakura, Nishigo, Fukushima, Japan.
Anim Sci J. 2017 Oct;88(10):1459-1464. doi: 10.1111/asj.12789. Epub 2017 Apr 12.
Hydrallantois is the excessive accumulation of fluid in the allantoic cavity in a pregnant animal and is associated with fetal death. We recently identified a recessive missense mutation in the solute carrier family 12, member 1 (SLC12A1) gene (g.62382825G>A, p.Pro372Leu) that is associated with hydrallantois in Japanese Black cattle. Unexpectedly, we found a case of the homozygous risk-allele for SLC12A1 in a calf, using a PCR-based direct DNA sequencing test. The homozygote was outwardly healthy up to 3 months of age and the mother did not exhibit any clinical symptoms of hydrallantois. In order to validate these observations, we performed confirmation tests for the genotype and a diuretic loading test using furosemide, which inhibits the transporter activity of the SLC12A1 protein. The results showed that the calf was really homozygous for the risk-allele. In the homozygous calf, administration of furosemide did not alter urinary Na or Cl levels, in contrast to the heterozygote and wild-type calves in which these were significantly increased. These results demonstrate that the SLC12A1 (g.62382825G>A, p.Pro372Leu) is a hypomorphic or loss-of-function mutation and the hydrallantois with this mutation shows incomplete penetrance in Japanese Black cattle.
积水性羊水过多是指怀孕动物羊膜腔内液体过度积聚，与胎儿死亡有关。我们最近在溶质载体家族12成员1（SLC12A1）基因中鉴定出一个隐性错义突变（g.62382825G>A，p.Pro372Leu），该突变与日本黑牛的积水性羊水过多有关。出乎意料的是，我们通过基于聚合酶链反应（PCR）的直接DNA测序检测，在一头小牛中发现了SLC12A1纯合风险等位基因的病例。该纯合子在3个月龄之前外表健康，其母亲也未表现出任何积水性羊水过多的临床症状。为了验证这些观察结果，我们对该基因型进行了确认测试，并使用呋塞米进行了利尿负荷试验，呋塞米可抑制SLC12A1蛋白的转运活性。结果表明，这头小牛确实是风险等位基因的纯合子。与杂合子和野生型小牛相比，在纯合小牛中，给予呋塞米后尿钠或氯水平没有改变，而在杂合子和野生型小牛中这些水平显著升高。这些结果表明，SLC12A1（g.62382825G>A，p.Pro372Leu）是一个亚效等位基因或功能丧失突变，并且携带这种突变的积水性羊水过多在日本黑牛中表现出不完全显性。
