CACNA1S基因突变致低钾周期性麻痹的产前基因诊断

目的对CACNA1S基因R1239H突变导致的低钾周期性麻痹（HoKPP1型）家系中的1例中期妊娠者进行产前基因诊断,从而预防HoKPP患儿出生。方法患者于16孕周在B超下进行羊膜囊穿刺,抽取羊水10 mL,提取羊水细胞基因组DNA。选择3个多态性STR位点,D13S317、D8S1179和D16S539,排除母体细胞的污染。在此基础上对CAC-NA1S基因外显子30进行扩增,PCR产物进行正、反向测序。结果 STR多态性位点分析,证明无母体细胞污染,胎儿CACNA1S基因30外显子测序结果显示,胎儿带有和母亲同样的CACNA1S基因突变R1239H。结论对于有HoKPP风险的胎儿进行产前基因诊断非常重要,可以明确胎儿基因型,预防患儿出生。     

Mutation screening in Chinese hypokalemic periodic paralysis patients

Thyrotoxic periodic paralysis (TPP), familial periodic paralysis (FPP), and sporadic periodic paralysis (SPP) are the most common causes of hypokalemic periodic paralysis (hypoKPP). The patients present with similar clinical features characterized by episodic attacks of muscle weakness and a decrease in blood potassium. Mutations in the gene encoding the voltage-sensor coding regions of the skeletal muscle sodium channel gene (SCN4A) and the alpha-1 subunit of the skeletal muscle calcium channel gene were analyzed in 23 Chinese hypoKPP patients, including 1 FPP pedigree, 14 TPP patients, and 8 SPP patients. In addition, R83H mutation of the potassium channel subunit gene which was originally published as periodic paralysis mutation was also analyzed. A heterozygous CGT-TGT mutation at codon 672 in SCN4A gene was identified to segregate with the disease in the FPP family. Mutations in these regions were excluded in those patients with SPP and TPP. The results suggest that a likely genetic basis for FPP does not contribute to TPP and SPP, despite close similarities among FPP, TPP, and SPP.     

The genotype and clinical phenotype of Korean patients with familial hypokalemic periodic paralysis

Familial hypokalemic periodic paralysis (HOPP) is a rare autosomal-dominant disease characterized by reversible attacks of muscle weakness occurring with episodic hypokalemia. Mutations in the skeletal muscle calcium (CACNA1S) and sodium channel (SCN4A) genes have been reported to be responsible for familial HOPP. Fifty-one HOPP patients from 20 Korean families were studied to determine the relative frequency of the known mutations and to specify the clinical features associated with the identified mutations. DNA analysis identified known mutations in 12 families: 9 (75%) were linked to the CACNA1S gene and 3 (25%) to the SCN4A gene. The Arg528His mutation in the CACNA1S gene was found to be predominant in these 12 families. Additionally, we have detected one novel silent exonic mutation (1950C>T) in the SCN4A gene. As for a SCN4A Arg669His mutation, incomplete penetrance in a woman was observed. Characteristic clinical features were observed both in patients with and without mutations. This study presents comprehensive data on the genotype and phenotype of Korean families with HOPP.     

一个中国家族性低钾型周期性麻痹家系中的CACNA1S基因R1239H突变

目的筛查家族性低钾型周期性麻痹（hypokalaemic periodic paralysis，HOKPP）相关基因突变位点，总结该病基因型和临床表型的相关性。方法应用PCR和DNA测序技术，对1个HOKPP家系（包括2例患者共11名成员）进行候选基因CACNA1S和SCN4A的筛查，并总结该家系患者的临床特点。结果此家系的2例患者符合HOKPP的诊断标准，突出特点为：儿童期发病，青春期加重，成年后病情减轻；女性在月经前期好发，而妊娠期无发作；钾剂和乙酰唑胺治疗有效。DNA测序结果发现2例患者的CACNA1S基因第30外显子上均存在3716（G→A）杂合突变，导致氨基酸序列改变R1239H，家族其他成员未见此突变。结论中国家族性HOKPP存在CACNA1S基因R1239H突变。     

Exploring the utility of whole‐exome sequencing as a diagnostic tool in a child with atypical episodic muscle weakness

The advent of whole‐exome next‐generation sequencing (WES) has been pivotal for the molecular characterization of Mendelian disease; however, the clinical applicability of WES has remained relatively unexplored. We describe our exploration of WES as a diagnostic tool in a 3½‐year old female patient with a 2‐year history of episodic muscle weakness and paroxysmal dystonia who presented following a previous extensive but unrevealing diagnostic work‐up. WES was performed on the proband and her two parents. Parental exome data was used to filter potential de novo genomic events in the proband and suspected variants were confirmed using di‐deoxy sequencing. WES revealed a de novo non‐synonymous mutation in exon 21 of the calcium channel gene CACNA1S that has been previously reported in a single patient as a rare cause of atypical hypokalemic periodic paralysis. This was unexpected, as the proband's original differential diagnosis had included hypokalemic periodic paralysis, but clinical and laboratory features were equivocal, and standard clinical molecular testing for hypokalemic periodic paralysis and related disorders was negative. This report highlights the potential diagnostic utility of WES in clinical practice, with implications for the approach to similar diagnostic dilemmas in the future.     

A Korean family of hypokalemic periodic paralysis with mutation in a voltage-gated calcium channel (R1239G)

Hypokalemic periodic paralysis (HOPP) is a rare disease characterized by reversible attacks of muscle weakness accompanied by episodic hypokalemia. Recent molecular work has revealed that the majority of familial HOPP is due to mutations in a skeletal muscle voltage-dependent calcium-channel: the dihydropyridine receptor. We report a 13-yr old boy with HOPP from a family in which 6 members are affected in three generations. Genetic examination identified a nucleotide 3705 C to G mutation in exon 30 of the calcium channel gene, CACNA1S. This mutation predicts a codon change from arginine to glycine at the amino acid position #1239 (R1239G). Among the three known mutations of the CACNA1S gene, the R1239G mutation was rarely reported. This boy and the other family members who did not respond to acetazolamide, showed a marked improvement of the paralytic symptoms after spironolactone treatment.     

泛素羧基端水解酶-L1基因两种多态与帕金森病发病的相关性

目的 探讨泛素羧基端水解酶-L1基因(ubiquitin carboxy-terminal hydrolase-L1,UCH-L1)第3外显子C/A多态、第4外显子C/T多态与帕金森病(Parkinson's disease,PD)发病风险的关系.方法 采用聚合酶链反应-限制性片段长度多态性方法,在164例PD患者和172名健康对照者中观察UCH-L1基因C/A和C/T多态的分布,并通过比值比(odds ratio,OR)进行相关分析.结果 (1)PD患者中UCH-L1第3外显子上C等位基因的频率(62.2%)明显高于对照组(51.7%)(OR=1.53,P=0.006),PD患者CC基因型的频率(36.6%)亦明显高于对照组(23.2%)(OR=1.90,P=0.008).(2)PD患者中UCH-L1第4外显子上C/T等位基因和基因型的频率分布在PD患者和对照组间差异无统计学意义.结论 UCH-L1第3外显子上c等位基因可能是PD发病的危险因子,而第4外显子上的C/T多态则与PD发病无关.     

中国汉族人ATM基因的单核苷酸多态与点突变

目的研究中国汉族人共济失调性毛细血管扩张症(ataxiatelangiectasiamutated,ATM)基因的单核苷酸多态和点突变。方法首先用PCR扩增ATM基因第39、61和63外显子的靶片段,然后用单链构象多态性(singlestrandconformationpolymorphism,SSCP)技术进行筛选,选择典型带型经全自动DNA测序证实。结果在ATM基因第39外显子以及第61和63内含子发现6个新的单核苷酸多态,它们分别是第39外显子第5689位和第5691位的A/T多态,第61内含子第 69位的T/G多态、第 94位的A/G多态和第 99位的T/G多态,第63内含子第 17位的G/C多态。在ATM基因第61外显子、第62内含子和第63外显子发现5个新的点突变,它们分别是第61外显子第8618位的T/G颠换、第62内含子第-13位的T/G颠换、第63外显子第8793位的T/G颠换、第8816位和第8848位的G/A转换。证实了ATM基因第39外显子第5557位G/A、第61内含子第 104位T/C和第62内含子第-55位T/C多态在中国汉族人中的存在。结论中国汉族人ATM基因的单核苷酸多态与白人存在较大差异。     

SLC22A12基因第8外显子和第8内含子多态与中国汉族人原发性高尿酸血症关联研究

目的 研究原发性高尿酸血症患者SLC22AI2基因第8内含子和第8外显子单核苷酸多态(single nucleotide polymorphism,SNP)位点与原发性高尿酸血症遗传易感性的关系.方法 选择山东沿海地区原发性高尿酸血症患者215例,正常对照人群323名.提取基因组DNA,PCR扩增SLC22A12基因第8内含子和第8外显子,对PCR扩增产物进行测序.结果 序列分析发现:(1)SLC22AI2基因第8外显子存在T1309C单核苷酸多态,第8内含子存在-103A＞G单核苷酸多态,这2个多态位点完全连锁.(2)高尿酸血症组-103A＞G G等位基因频率和T1309C C等位基因频率明显高于正常对照组(均为51.9%vs.42.4%,P＜0.01);(3)高尿酸血症组GG+GA基因型频率和CC+CT基因型频率显著高于正常对照组(均为80.0%vs.69.0%,P＜0.01).(4)-103 A＞G和T1309C基因多态中,含有等位基因G的基因型GG+GA及含有等位基因C的基因型CC+CT均使高尿酸血症的发病危险性上升了1.79倍(OR=1.79,95%CI:1.19～2.70).结论 SLC22A12基因第8外显子T130gC及第8内含子-103A＞G SNP与原发性高尿酸血症密切相关.     

Thyrotoxic periodic paralysis: a report of 3 Malaysian cases and a review of its pathology

Thyrotoxic periodic paralysis (TPP) is a medical emergency characterised by sudden onset of muscle weakness with hypokalemia that resolves with the treatment of hyperthyroidism. We report three cases of thyrotoxic periodic paralysis seen at the Accident and Emergency Care Department, University of Malaya Medical Centre in a period of four months. We also review the clinical presentation, pathophysiology, biochemical features and management of TPP. All three patients were young Asian males, presenting with muscle weakness of sudden onset. The first patient presented with lower limb weakness and had symptoms of thyrotoxicosis and goitre. He had a previous similar episode which resolved spontaneously. The second patient presented with quadriplegia, respiratory acidosis and had no signs and symptoms of thyrotoxicosis. The electrocardiogram of this patient showed normal sinus rhythm with U wave in V3 and a flat T wave, which are characteristic of hypokalaemia. The third patient, who was a known case of thyrotoxicosis, was admitted thrice for hypokalemic paralysis during the study period. All cases had low serum potassium, suppressed TSH and elevated T4 confirming thyrotoxic periodic paralysis. Potassium therapy was useful during the crisis; however prophylactic potassium has not been shown to prevent attacks as seen in one of our cases. Conclusion: Thyrotoxic periodic paralysis should be considered in the differential diagnosis of sudden onset paralysis in young male patients. Determination of the plasma potassium levels and thyroid hormones help in the diagnosis. The definitive treatment for TPP is the achievement of euthyroid state.     

Analysis of MDR1 haplotypes in Parkinson's disease in a white population

The MDR1 multidrug transporter is important in regulating environmental xenobiotics and hence may play a causative role in Parkinson's disease (PD). MDR1 haplotype comprising 2677 G > T/A and 3435 C > T may be protective against PD. Using a case control methodology, we investigated the association of MDR1 haplotypes (single nucleotide polymorphisms (SNPs) 2677 G > T/A and 3435 C > T) in a Polish PD population. Seven SNPs, extending from the promoter to exon 28 of the MDR1 gene in 158 PD patients and 139 healthy controls were evaluated. Specifically we examined the association of haplotypes containing SNPs 2677 G > T/A and 3435 C > T and risk of PD. The multivariate logistic regression model was used to evaluate the effects of the covariates on the phenotypes. Haplotypes' frequencies were estimated using the Expectation-Maximization algorithm. The frequency of each individual SNPs; -41 A > G (intron -1), -145 C > G (exon 1), -129 T > C (exon 1), 1236 T > C (exon 12), 2677 G > T/A (exon 21), 3435 C > T (exon 26), and 4036 A > G (exon 28) did not differ between PD and controls. However, there was a trend towards significance in PD patients having the haplotype 2677G-3435C (p < 0.09, chi-square 2.85, odds ratio 0.25, 95% CI 0.06-1.08). Haplotype constructs of the other loci did not differ significantly between the two groups. There was a weak protective effect of the haplotype 2677G-3435C in our white population. However, the MDR1 haplotypes did not generally modulate the risk of PD.     

Haplotype and linkage disequilibrium analysis to characterise a region in the calcium channel gene CACNA1A associated with idiopathic generalised epilepsy

Idiopathic generalised epilepsy (IGE) is a common form of epilepsy, including several defined and overlapping syndromes, and likely to be due to the combined actions of mutations in several genes. In a recent study we investigated the calcium channel gene CACNA1A for involvement in IGE, unselected for syndrome, by means of association studies using several polymorphisms within the gene. We reported a highly significant case/control association with a silent single nucleotide polymorphism (SNP) in exon 8 that we confirmed by within-family analyses. In this present study we screened the gene for novel SNPs within 25 kb of exon 8, which have enabled us to define the critical region of CACNA1A in predisposing to IGE. Several intronic SNPs were identified and three, within 1.5 kb of exon 8 and in strong linkage disequilibrium with each other and with the original SNP, were significantly associated with IGE (P=0.00029, P=0.0015 and P=0.010). The associations were not limited to an IGE syndrome or other subgroup. Another SNP, 25 kb away, in intron 6 was also significantly associated with IGE (P=0.0057) but is not in linkage disequilibrium with the SNPs around exon 8. Haplotype predictions revealed even more significant associations (3-marker haplotype: P<10(-6)). Logistic regression showed that all the data can be explained by two of the SNPs, which is consistent with two functionally significant variants being responsible for all five associations, although a single variant cannot be excluded. The functionally significant variant(s) are unlikely to be exonic and suggests an effect on expression or alternative splicing.     

Identification of polymorphisms in the XIAP gene and analysis of association with lung cancer risk in a Korean population

The X-linked inhibitor of apoptosis protein (XIAP) is a potent mammalian IAP, and has been shown to play an important role in development and progression of cancer. Polymorphisms in the XIAP gene may influence XIAP production or activity, thereby modulating susceptibility to lung cancer. To test this hypothesis, we first screened for polymorphisms in the XIAP gene by direct sequencing of genomic DNA samples from 27 healthy Korean women and then performed a case-control study to evaluate the association between the polymorphisms and the risk of lung cancer. The XIAP genotypes were determined by polymerase chain reaction amplification and melting curve analysis in 582 lung cancer patients and in 582 healthy control subjects who were frequency-matched for age and sex. We identified 12 single nucleotide polymorphisms (SNPs), one novel SNP [30051C>G (A321G) in exon 3] and the following 11 known SNPs: 192G>C (rs5956578), 262C>T (rs28382699), 318C>T (rs5958318), and 374C>T (rs12687176) in the putative promoter; 26615A>G (rs2355676) in intron 1; 41725A>G (rs5958338) in intron 5; 42009A>C (Q423P, rs5956583) in exon 6; 48162T>C (rs17334739) and 48228C>T (rs28382739) in intron 6; and 48542A>G (rs28382740) and 49333G>T (rs28382742) in 3'-UTR. Four of these 12 SNPs were selected for large-scale genotyping based on their frequencies and haplotype tagging status: 262C>T, 318C>T, 374C>T, and 42009A>C. The four XIAP polymorphisms and their haplotypes exhibited no apparent relationship with the risk of lung cancer. In addition, we observed no evidence of effect modification by age, sex, smoking history, or tumor histology. These results suggest that XIAP polymorphisms do not significantly affect susceptibility to lung cancer in Koreans.     

Common Polymorphisms in the CACNA1H Gene Associated with Childhood Absence Epilepsy in Chinese Han Population

Variants with a relatively high frequency in the CACNA1H gene have previously been identified in cases of childhood absence epilepsy (CAE) in the Chinese Han population most of which are located in exons 6 to 12. In present study we attempted to further investigate whether the CACNA1H gene is associated with CAE. Exons 6 to 12 of CACNA1H gene were sequenced in samples of 100 CAE trios recruited consecutively, and 191 normal human controls. Single nucleotide polymorphisms (SNPs) were studied in both single locus and haplotype analyses in 218 CAE trios, of which 118 trios were selected from our previous research. Case-control comparisons and the transmission disequilibrium test (TDT) both supported a coding SNP (cSNP) rs9934839 (R603R) in exon 9 as being close related to CAE. The carriers of the G allele of rs9934839 had a 3-fold higher risk of CAE than non-carriers. Moreover, another cSNP rs8044363 was predicted to be connected directly with CAE in a Bayesian network. In addition, two haplotypes consisting of five cSNPs in the region of CACNA1H were statistically associated with CAE. Our research provides new evidence to further support the hypothesis that CACNA1H may be an important susceptibility gene for CAE in the Chinese Han population.     

Association study between brain-derived neurotrophic factor gene polymorphisms and methamphetamine abusers in Japan.

Several lines of evidence suggest that genetic factors might contribute to drug abuse vulnerability. Recent genomic scans for association demonstrated that the brain-derived neurotrophic factor (BDNF) gene was associated with drug abuse vulnerability. In this study, we analyzed association of two BDNF gene single nucleotide polymorphisms (SNPs), 132C > T (C270T named formerly) in the noncoding region of exon V and 196G > A (val66met) in the coding region of exon XIIIA, with methamphetamine (MAP) abuse in Japan. No significant differences were found in the frequency of the genotype or allele in these two SNPs between MAP abusers and controls (132C > T in exon V: genotype, P = 0.586, allele, P = 0.594; 196G > A (val66met) in exon XIIIA: genotype, P = 0.889, allele, P = 0.713). Furthermore, there was no difference between clinical parameters (e.g., prognosis psychosis, spontaneous relapse, or poly-substance abuse) and the two SNPs of BDNF gene. These results suggest that the two SNPs (132C > T in exon V and 196G > A (val66met) in exon XIIIA) of the BDNF gene may not be associated with Japanese MAP abusers. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148-7299:1/suppmat/index.html.     

MMP14 gene polymorphisms in chronic obstructive pulmonary disease

Proteinase/antiproteinase imbalance is a widely accepted theory for the pathogenesis of COPD. Among various proteinases, matrix metalloproteinases (MMPs) digest extracellular matrix of the lung and play significant roles in the development of COPD. Polymorphisms of an MMP that upregulate its activity may result in the degradation of the lung matrix. A case-control study was performed to investigate the association of polymorphisms of the MMP14 gene with COPD. Japanese subjects (96 COPD patients and 61 controls) and Egyptian subjects (106 COPD patients and 72 controls) were recruited. Each subject was genotyped for seven single nucleotide polymorphisms (SNPs) of the MMP14 gene; -165 G/T and -72 G/A in the promoter region, +221 C/T in exon 1, +6727 C/G and +6767 G/A in exon 5, +7096 T/C in exon 6, and +8153 G/A in exon 8. The distributions of the genotype frequencies of these SNPs were not significantly different between the COPD patients and the controls in either ethnic group after correction of multiple comparisons. In the haplotype analysis, however, the haplotype -165 T : +221 T : +6727 C : +7096 C had a significantly higher frequency in the Egyptian COPD group than the control group (pcorr = 0.0063). The haplotype of the MMP14 gene, -165 T : +221 T : +6727 C : +7096 C, might be involved in the pathogenesis of COPD.     

Modifications in the sarcoplasmic reticulum and subcellular calcium distribution in skeletal muscle in a case of Westphal's disease (hypokalemic periodic paralysis)

Summary In a case of hypokalemic periodic paralysis with characteristic alterations of the sarcoplasmic reticulum (SR) in the skeletal muscle, subcellular calcium re-partition, as revealed with the pyroantimonate technique, appears disturbed during paralysis. Pyroantimonate precipitates, normally concentrated in the terminal cisternae of the SR, were localized in the T tubules, whereas the terminal cisternae appeared empty. The increase (about 14%) in muscular calcium during paralysis may result from the accumulation of calcium in the extracellular compartment (T tubules). Defects in calcium uptake and storage by the SR may be. involved in the pathogenesis of the periodic paralysis syndrome.     

低钾型周期性麻痹一家系相关基因分析

目的筛查低血钾性周期性麻痹家系的骨骼肌二氢吡啶受体敏感的钙离子通道α1亚基、骨骼肌电压门控钠离子通道α亚基基因和钾离子通道KCNE3基因突变。方法以NaI法提取患者和对照组新鲜外周抗凝血白细胞DNA,进行目的片段的PCR扩增。然后对PCR产物作SSCP分析,最后对部分小片段产物行克隆测序,较大片段产物直接测序。结果发现钙离子通道α1亚基11号外显子和26号外显子上共三个无义突变,其他位点均无突变。结论该家系HypoPP发病机制可能存在另外的基因突变,有待进一步研究。     

Novel O6-methylguanine-DNA methyltransferase SNPs: a frequency comparison of patients with familial melanoma and healthy individuals in Sweden

The DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT) is involved in the cellular defense against alkylating agents. Genetic alterations in the MGMT gene may impair the protein's ability to remove alkyl groups from the O6-position of guanine, thereby raising the mutation rate and increasing the risk of cancer. We assessed polymorphisms in the promoter region and the 5 exons of the MGMT gene by PCR/SSCP and nucleotide sequence analysis of DNA extracted from blood samples. The population studied consisted of 89 melanoma patients, each belonging to a different family with a hereditary predisposition for melanoma, and 76 healthy individuals (blood donors). A total of 11 single nucleotide polymorphisms (SNPs) were detected, five in the promoter region, one in exon 1, two in exon 3 and three in exon 5. Six of the alterations were novel polymorphisms, of which five were located in the promoter region and one in exon 5. When the distribution of specific SNPs in cases and controls with only one variant was calculated; C575A was present only in melanoma patients (p=0.072). Moreover, while 20% of the healthy individuals had no SNPs this was the case in only 12.4% of the melanoma patients. However, no statistically significant differences were seen between cases and controls for any of the 11 SNPs.