一例 Kallmann 综合征患者双基因突变分析

摘要

目的：分析 Kallmann 综合征( Kallmann syndrome, KS)患者 KS1( Kallmann syndrome 1, KAL1),前动力蛋白2(prokineticin 2,PROK2)和前动力蛋白受体2(prokineticin receptor 2,PROKR2)3个基因的突变情况。方法①采用放射免疫分析法检测激素水平,超声扫描评估腹部结构,脑部磁共振成像(magnetic resonance imaging,MRI)检测嗅球、脑沟和内耳的结构。②运用聚合酶链式反应(polymerase chain reaction,PCR),结合 PCR 产物直接测序技术分析 KAL1、PROK2和 PROKR23个基因外显子突变。③分别利用 SIFT、Polyphen 和 Mutation Taster 3种生物信息学平台进行了错义位点和多态性位点的功能分析。结果①患者青春期发育不良,嗅觉减退,其父母无症状。②在患者基因组中找到2个 KAL1杂合突变位点(Ile 565 Thr 和 Ser 570 Thr),5个 KAL1基因单核苷酸多态性位点(single nucleotide polymorphism,SNP)：Val 534 Ile、Val 560 Phe、Gly 567 Ser、Lys 666 Met和 Agr 668 His,以及一个 PROKR2纯合突变位点(Tyr 113 His)。同时也在患者父母基因组中检测到 PROKR2杂合突变位点(Y113H)。③生物信息学分析结果显示 I565T、S570T 和 Y113H(PROKR2)3个位点可能是该患者的致病基因位点。结论这2个新的突变位点还未在中国人群中报道过,这也是国内报道的第1例同时带有2个 KAL1突变和一个 PROKR2突变的 KS 患者,表明该患者可能是一个双基因遗传的 KS 患者。%Objective To analyze the mutation of Kallmann syndrome 1(KAL1), prokineticin(PROK2) and prokineticin receptor 2 (PROKR2) in a family, which has a 13-year-old son with Kallmann syndrome(KS). Methods ① Hormone levels were measured by immunoradiometric assay, abdomen structures were assessed by abdominal ultrasound scan, brain magnetic resonance imaging(MRI) was used to visualize the olfactory bulbs, sulci, and inner ears; ② The exon sequences of the three genes(KAL1, PROK2 and PROKR2) were screened for a mutation by direct sequencing; ③ SIFT, Polyphen and MutationTaster were used as a complementary approach to assess the significance of polymorphisms and missense mutations. Results ① The patient had sexual infantilism, and the MRI of the head revealed the dysplasia of olfactory bulbs and olfactory tract; the parents of this patient had normal pubertal development, serum gonadotropin and estradiol concentrations, and their MRI results showed normal olfactory bulbs; ② In KAL1 gene, two novel mutations(I565T and S570T) and five previously described polymorphisms(V534I, V560F, G567S, K666M and R668H) were detected in this patient. In PROKR2 gene, a homozygous Y113H was presented in this patient, and this mutation was also detected in the heterozygous state in his parents; ③I565T, Y113H (PROKR2) and S570T may be the harmful variation according to our stringent analysis. Conclusion To date, these two novel mutations have not yet been reported in the Chinese population, and this is the first case of KS patient who exhibited two-point mutation in KAL1 and was also carried a missense mutation in PROKR2, thus indicating a possible digenic inheritance of the disease in this individual.