Das Dhanjit Kumar, Rahate Subodh G, Mehta Bhakti P, Gawde Harshavardhan M, Tamhankar Parag M
Genetic Research Centre, National Institute for Research in Reproductive Health, Parel, Mumbai, Maharashtra, India.
Indian J Hum Genet. 2013 Oct;19(4):437-42. doi: 10.4103/0971-6866.124372.
Determination of sex is the result of cascade of molecular events that cause undifferentiated bipotential gonad to develop as a testis or an ovary. A series of genes such as SRY, steroidogenic factor-1 (SF1), AR, SRD5 α, Desert hedgehog (DHH) etc., have been reported to have a significant role in development of sex in the fetus and secondary sexual characteristics at the time of puberty. Recently, mitogen activated protein kinase kinase kinase 1 (MAP3K1) gene was found to be associated with 46, XY disorders of sex development (DSD).
The present study is focused to identify mutations in MAP3K1 gene in the cohort of 10 Indian patients with 46,XY DSD including one family with two affected sisters. These patients were already screened for SRY, SF1 and DHH gene, but no mutation was observed in any of these genes.
The entire coding regions of MAP3K1 were amplified and sequenced using the gene specific primers.
Sequence analysis of MAP3K1 gene has revealed four variants including one missense, two silent and one deletion mutation. The missense mutation p.D806N was observed in four patients with hypospadias. Two patients showed the presence of silent mutation p.Q1028Q present in exon 14. Another silent mutation p.T428T was observed in a patient with gonadal dysgenesis. We have also observed one deletion mutation p. 942insT present in two patients. The pathogenicity of the missense mutation p.D806N was carried out using in-silico approach. Sequence homology analysis has revealed that the aspartate at 806 was found to be well-conserved across species, indicated the importance of this residue. The score for polyphen analysis of this mutation was found to be 0.999 indicating to be pathogenic mutation. Since, p.D806N mutation was found to be important residue; it might contribute to sexual development. We have reported the presence of mutations/polymorphism in MAP3K1 gene. All the mutations were found to be polymorphism upon comparing to single nucleotide polymorphism database. However, in-silico analysis of the missense mutation revealed to be a pathogenic mutation.
性别的确定是一系列分子事件的结果，这些事件导致未分化的双潜能性腺发育为睾丸或卵巢。据报道，一系列基因，如SRY、类固醇生成因子-1（SF1）、雄激素受体（AR）、5α-还原酶（SRD5α）、沙漠刺猬因子（DHH）等，在胎儿性别发育和青春期第二性征形成中起重要作用。最近，有研究发现丝裂原活化蛋白激酶激酶激酶1（MAP3K1）基因与46，XY性发育障碍（DSD）有关。
本研究旨在对10例印度46，XY DSD患者（包括一个有两名患病姐妹的家庭）进行MAP3K1基因突变检测。这些患者已对SRY、SF1和DHH基因进行过筛查，但未发现任何这些基因有突变。
使用基因特异性引物扩增并测序MAP3K1的整个编码区。
MAP3K1基因序列分析发现了4个变异，包括1个错义突变、2个沉默突变和1个缺失突变。在4例尿道下裂患者中发现了错义突变p.D806N。2例患者显示外显子14存在沉默突变p.Q1028Q。在1例性腺发育不全患者中发现了另一个沉默突变p.T428T。我们还在2例患者中发现了1个缺失突变p.942insT。采用计算机模拟方法对错义突变p.D806N的致病性进行了分析。序列同源性分析显示，806位的天冬氨酸在不同物种间高度保守，表明该残基的重要性。该突变的多态性分析得分高达0.999，表明是致病性突变。由于p.D806N突变是一个重要残基，它可能对性发育有影响。我们报道了MAP3K1基因中存在突变/多态性。与单核苷酸多态性数据库比较后发现所有突变均为多态性。然而，计算机模拟分析显示该错义突变是致病性突变。
