Detection of azoospermic factor genes in Chinese men with azoospermia or severe oligozoospermia. (33/8027)

PURPOSE: We investigated the prevalence of deletions in the azoospermic factor (AZF) region of chromosome Yq11 in Chinese men with infertility due to idiopathic azoospermia or severe oligozoospermia. The DAZ gene cluster was also examined for mutations. METHODS: Sixty-eight men with azoospermia or severe oligozoospermia taking part in an intracytoplasmic sperm injection program were recruited. Four loci specific for AZFa, AZFb, and AZFc were amplified from genomic DNA via polymerase chain reaction to determine whether deletions were present in the AZF region. Direct DNA sequencing of amplified products was also performed to look for mutations or polymorphism from exon 2 to exon 6 of the DAZ gene cluster. RESULTS: Six (9%) of the 68 patients had AZF deletions. None had mutations in exons 2 to 6 of DAZ. CONCLUSIONS: The prevalence of AZF deletions in our study was similar to those in Western reports, as was the lack of DAZ mutations.  (+info)

Hepatitis B carriage explains the excess rate of hepatocellular carcinoma for Maori, Pacific Island and Asian people compared to Europeans in New Zealand. (34/8027)

BACKGROUND: The aim of this research was to determine the hepatitis B surface antigen (HBsAg) carrier prevalence among cases of hepatocellular carcinoma (HCC), and the population attributable risk of HBsAg carriage for HCC, by ethnicity in New Zealand. METHODS: The hospital notes of HCC cases registered with the New Zealand Cancer Registry, for the years 1987-1994 inclusive, were viewed to determine the HBsAg status. Results The HBsAg status was determined for 193 cases of HCC. The HBsAg carrier prevalence for non-Europeans with HCC was markedly higher than that for Europeans, being 76.7% for Maori, 80.0% for Pacific Island people, and 88.5% for Asians, compared to 6.0% for Europeans. In addition to the effect of ethnicity, HCC cases aged <60 years were more likely to be HBsAg carriers than those aged > or = 60 years. The estimated population attributable risk of HBsAg for HCC, within each ethnic group, was only marginally less than the HBsAg prevalence due to the high relative risk of HBsAg carriage for HCC. The standardized incidence rate ratios of HCC for Maori, Pacific Island people and Asians compared to Europeans were 9.6, 20.4, and 22.3, respectively. Hepatocellular carcinoma attributable to HBsAg carriage explained 79%, 83%, and 92% of the excess standardized rate of HCC, compared to Europeans, for Maori, Pacific Island people, and Asians, respectively. Conclusions The HBsAg carrier prevalence in non-European cases of HCC in New Zealand is between 75% and 90%. HBsAg carriage explains the majority of the excess rate of HCC in non-Europeans compared to Europeans in New Zealand.  (+info)

Survival advantage in Asian American end-stage renal disease patients. (35/8027)

Survival advantage in Asian American end-stage renal disease patients. BACKGROUND: An earlier study documented a lower mortality risk for end-stage renal disease (ESRD) patients in Japan compared with the United States. We compared the mortality of Caucasian (white) and Asian American dialysis patients in the United States to evaluate whether Asian ancestry was associated with lower mortality in the United States. METHODS: The study sample from the U.S. Renal Data System census of ESRD patients treated in the United States included 84,192 white or Asian patients starting dialysis during May 1995 to April 1997, of whom 18,435 died by April 30, 1997. Patient characteristics were described by race. Relative mortality risks (RRs) for Asian Americans relative to whites were analyzed by Cox proportional hazards regression models adjusting for characteristics and comorbidities. Population death rates were derived from vital statistics for the United States and Japan by age and sex. RESULTS: Adjusting for demographics, diabetes, comorbidities, and nutritional factors, the RR for Asian Americans was 0.75 (P = 0.0001). Race-specific background population death rates accounted for over half of the race-related mortality difference. For whites, mortality decreased as the body mass index (BMI) increased. For Asians, the relationship between BMI and survival was u-shaped. The ratio of Asian American/white dialysis death rates and the ratio of Asian American/white general population death rates both varied by age in a similar pattern. The population death rates of Asian American and Japanese were also similar. CONCLUSION: Among dialysis patients, Asian Americans had a markedly lower adjusted RR than whites. The effect of BMI on survival differed by race. Compared with the respective general population, dialysis patients had the same relative increase in death rates for both races. The difference in death rates between the United States and Japan does not appear to be primarily treatment related, but rather is related to background death rates.  (+info)

Detection of the most common G6PD gene mutations in Chinese using amplification refractory mutation system. (36/8027)

Glucose-6-phosphate dehydrogenase (G6PD) is the most common human enzymopathy. To date more than 122 mutations in the G6PD gene have been discovered, among which 12 point mutations are found in the Chinese. The 2 most common mutations, G1388A and G1376T, account for more than 50% of mutations representing various regions and ethnic groups in China. Setting up a simple and accurate method for detecting these mutations is not only useful for studying the frequency of the G6PD genotypes, but also for finding new mutations. The purpose of this study was to find a simple, inexpensive and accurate method for detecting these common mutations. The amplification refractory mutation system (ARMS) method was used in this study. Samples from 28 G6PD-deficient males were investigated. The natural and mismatched amplification and restriction enzyme digestion method was used as a standard method to evaluate the nature of the point mutations. Sixteen cases were found carrying the G1388A mutation and 12 the G1376T mutation. Fourteen cases of G1388A and 10 cases of G1376T were confirmed by ARMS. Four cases were not in concordance with the results obtained by the mismatched amplification-restriction enzyme digestion. These 4 cases were then judged by direct PCR sequencing at exon 12. The DNA sequencing data supported the results obtained by ARMS. Thus we concluded that the ARMS is a rapid, simple, inexpensive and accurate method for detecting the most common G6PD gene mutations among the Chinese.  (+info)

Genetic heterogeneity for familial hypertrophic cardiomyopathy in Chinese: analysis of six Chinese kindreds. (37/8027)

OBJECTIVE: Familial hypertrophic cardiomyopathy (FHCM) is a primary myocardial disease characterized by unexplained ventricular hypertrophy. The application of the techniques of reverse genetics has identified at least five chromosomal loci as the major causes for FHCM in diverse ethnic populations, suggesting substantial genetic heterogeneity for FHCM. Recently, the defective gene loci of two Chinese families with FHCM have been mapped to chromosome 11 and 14q1, respectively. For further understanding of the molecular basis of FHCM in Chinese, we analyzed the linkage between four other Chinese kindreds and DNA markers from chromosome 14q1. METHODS: Six unrelated Chinese families with FHCM, including two previously reported, were studied. Totally 90 family members were included for analysis. DNA from 80 individuals was extracted and polymerase chain reactions were performed using the primers designed according to the sequences derived from the alpha and beta myosin heavy chain gene. Totally four polymorphisms were studied, including three polymorphic microsatellite sequences and one single strand conformation polymorphism. Genetic linkage analysis were performed using the Linkage program. RESULTS: In the six studied families, 39 of the 90 family members were found to be affected diagnosed either by echocardiography or by clinical evaluation. The pattern of inheritance in all six studied families was most consistent with an autosomal dominant trait with a high degree of penetrance. Genetic linkage analysis using polymorphisms on the alpha and beta MHC genes showed a combined maximal lod score of 6.2 for trinucleotide repeat polymorphism AMHC-I 15 at theta = 0.00 for three studied families without recombination. Exclusion of linkage to the chromosome 14q1 location was noted in two of three other families with the maximal lod score of -2 or less. CONCLUSIONS: These results provide further evidence that FHCM in Chinese is genetically heterogeneous. Chromosome 14q1 locus, probably the beta myosin heavy chain gene, is important as the molecular basis for FHCM in Chinese.  (+info)

Trinucleotide repeat expansion of spinocerebellar ataxia (SCA1) found in a Chinese family. (38/8027)

OBJECTIVE: To investigate the gene mutation and the ratio of the spinocerebellar ataxia type 1 (SCA1) in Chinese patients with autosomal dominant spinocerebellar ataxia (ADSCA). METHOD: The family material and DNA samples were collected from thirteen families with ADSCA. To determine the characteristics of the CAG trinucleotide repeats in SCA1 gene, the PCR products of the Rep1 and Rep2 primers were analyzed, and the bands with CAG repeat expansion were cloned by PCR2. 1 vector and sequenced. RESULTS: One family was found to have an expanded CAG repeat in the 13 families with ADSCA. The clinically affected individual was heterozygous with one disease allele being 55 CAG repeats, whereas the mean size of the CAG repeats on 104 chromosomes generated from unrelated control Chinese individuals is 29.3 (ranging from 18 to 34). CONCLUSIONS: The frequency of the SCA1 mutation is about 7% in the 13 Chinese families with ADSCA, suggesting that this type of genetic defect is not the main cause involved in the pathogenesis of ADSCA in China. Since the mutation has also been found in Caucasian, Japanese, Malaysian, and Bangladeshi kindreds, it is suggested that this genetic defect may well have multiple origins in different ethnic groups.  (+info)

N-ras mutations in 43 Chinese cases of acute myeloid leukemia. (39/8027)

OBJECTIVE: To detect 3 kinds of N-ras mutations in Chinese patients with acute myeloid leukemia (AML). METHODS: In vitro DNA amplification followed by oligonucleotide dot analysis were used to study N-ras gene mutations in 43 cases of acute myeloid leukemia (AML). 25 healthy people were used as controls. Patients were selected in the Beijing district and consisted of 19 males and 24 females. The average age was 37. The controls were healthy individuals with the average age of 36.5 from the same region. 3 oligonucleotide probes were artificially synthesized to detect mutations in codon 12 and 13 of N-ras. RESULTS: Five out of 43 AML samples have been found contain G-->A mutation in codon 12.2 have G-->T mutation in codon 12. One has G-->A mutation in codon 13. The mutation rate was 18.6%. None of the controls presented these mutations. The frequency of mutation of N-ras in the AML samples showed statistical differences with that of the controls. CONCLUSION: Analysis of the results suggests the N-ras mutations may have some relationship with the etiology of acute myeloid leukemia.  (+info)

Obstructive sleep apnea syndrome: an experience in Chinese adults in Hong Kong. (40/8027)

OBJECTIVE: Epidemiologic studies in Caucasian populations suggested that symptomatic obstructive sleep apnea (OSA) occurred at a prevalence of 1-10%. The condition has been increasingly recognised among the Chinese in Hong Kong. We therefore, summarize our experience with OSA at the Department of Medicine, The University of Hong Kong at Queen Mary Hospital from 1985-1996. METHODS: All clinic records concerning demographic data, anthropometric data, clinical features, polysomnographic findings and treatment were reviewed. RESULTS: One hundred and twenty-two patients were diagnosed to have OSA. Demographic and clinical features were similar to Caucasian data with a male predominance of 84%, a mean age of about 50 years, and obesity as a risk factor at a mean body mass index of 30.4, which was higher than that of the average local population, although lower than that of OSA patients in Caucasian series. About 27% of the patients have a body mass index (BMI) similar to or below the population average. Nearly all were habitual snorers, and the majority had excessive daytime sleepiness. On polysomnography, the mean apnea-hypopnea index was 38. Common associated medical conditions were hypertension (34%), diabetes mellitus (10%), ischemic heart disease (9%), hyperlipidemia (6%). Most patients were managed successfully with nasal continuous positive airway pressure. Treatment with oral appliances for milder cases is being explored. CONCLUSIONS: OSA has been increasingly recognised among Chinese adults in Hong Kong in the past decade. Demographic features were similar to Caucasian data. The majority of patients were overweight, although 27% were not, and further investigation on the contribution of faciomaxillary morphology to OSA in this group is warranted.  (+info)