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目的对苍白球黑质变性(HSD)2个家系进行泛酸激酸2(PANK2)基因突变位点的筛查。方法分别抽取2个家系4名成员外周静脉血各2 mL,盐析法提取2个家系成员基因组DNA,用PCR方法扩增PANK2基因的全部编码外显子,纯化后直接测序。结果在1号先证者的PANK2基因上发现2个杂合的错义突变:外显子2上核苷酸序列第970位G>T突变(c.970G>T),导致编码的第324位氨基酸由天门冬氨酸(D)变成酪氨酸(Y)(D324Y);患儿母亲是这一突变的杂合携带者,具有正常表型。外显子3上核苷酸序列第1133位A>G突变(c.1133A>G),导致编码的第378位氨基酸从天门冬氨酸(D)变成甘氨酸(G)(D378G);患儿父亲是这一突变的杂合携带者,具有正常表型。在2号先证者的PANK2基因上发现2个杂合的错义突变:外显子2上核苷酸序列第808位C>G突变(c.808C>G),导致编码的第270位氨基酸由亮氨酸(L)变成缬氨酸(V)(L270V);外显子3上核苷酸序列第1103位A>G突变(c.1103A>G),导致编码的第368位氨基酸从天门冬氨酸(D)变成甘氨酸(G)(D368G);该患儿为抱养儿,无法检测其父母的基因型。这4个错义突变均能引起PANK2基因编码氨基酸的改变,从而引起蛋白质结构和功能的异常。结论在这2个家系中,c.970G>T、c.1133A>G、c.808C>G和c.1103A>G错义突变导致2个先证者出现HSD的表型。
Objective To screen psoriatic acid 2 (PANK2) gene mutations in two pedigrees of globus pallidus substantia nigra degeneration (HSD). Methods Two peripheral venous blood samples of 2 members of 2 pedigrees were collected respectively. Genomic DNA was extracted from 2 pedigrees by salting-out method. All coding exons of PANK2 gene were amplified by PCR and sequenced directly after purification. Results Two heterozygous missense mutations were found on the PANK2 gene of proband 1: a G> T mutation at position 970 of the nucleotide sequence at exon 2 (c.970G> T) The amino acid changes from aspartic acid (D) to tyrosine (Y) (D324Y); the mother of the child is a heterozygous carrier of this mutation and has a normal phenotype. A> G mutation at position 1133 (c.1133A> G) in the nucleotide sequence of exon 3 resulted in the conversion of encoded amino acid 378 from aspartic acid (D) to glycine (G) (D378G); affected Her father is a heterozygous carrier of this mutation, with a normal phenotype. Two heterozygous missense mutations were found on the PANK2 gene of proband 2: a C> G mutation at position 808 of the nucleotide sequence at exon 2 (c.808C> G), leading to the 270th The amino acid changed from leucine (L) to valine (V) (L270V); amino acid sequence A> G at position 1103 of exon 3 (c.1103A> G) The amino acid changed from aspartate (D) to glycine (G) (D368G); the child was a toddler and could not detect the parental genotype. These four missense mutations can cause PANK2 gene encoding amino acid changes, causing the protein structure and function of the abnormal. Conclusion The missense mutations c.970G> T, c.1133A> G, c.808C> G and c.1103A> G resulted in the phenotypes of HSD in two probands.