Alpha 1-protease inhibitor (PI) subtypes in seven populations of east Asia

Molecular characterization of PI * S hangzhou , a SERPINA1 allele from continental China encoding a defective alpha-1-antitrypsin

Alpha-1-antitrypsin deficiency (AATD) is a heritable condition that predisposes to respiratory and hepatic complications. Screenings in East Asia human populations for the AATD alleles most commonly found among Caucasians have yielded poor outcomes. Serum alpha-1-antitrypsin (AAT) levels, AAT phenotypes, and sequences of SERPINA1 gene were examined in a Chinese child with a moderate deficit of serum AAT, who had suffered several episodes of liver disease, as well as in his first-order relatives. Results allowed the identification of PI ^* S _hangzhou , a novel SERPINA1 defective allele, which has been characterized by a L276R substitution, found in a SERPINA1-M3 genetic background. Moreover, potential effects of PI ^* S _hangzhou mutation over the AAT structure were studied by 3D homology modeling. The presence of an arginine residue at position 276 could destabilize the tertiary structure of AAT, since it occurs at a highly conserved hydrophobic cavity in the protein surface, and very close to two positively-charged lysine residues. Attending to the frequency of R276 variant reported in databases for individuals of East Asian ancestry, the PI ^* S _hangzhou allele may explain the global prevalence of the PiS phenotype observed in China.

alpha1-Antitrypsin deficiency is not an important cause of childhood liver diseases in a multi-ethnic Southeast Asian population

AIM

We conducted a prospective study to determine the role of alpha1-antitrypsin (alpha1AT) deficiency in the pathogenesis of neonatal cholestasis and other childhood liver diseases in a multi-ethnic Southeast Asian population.

METHODS

Prospective patients with neonatal cholestasis (group 1), other liver diseases (group 2) and children with other medical conditions (group 3) referred to the Paediatric Unit, University of Malaya Medical Centre, Malaysia, from May 2002 to June 2005, were screened for alpha1AT level and phenotype. alpha1AT level below 80 mg/dL was considered as low.

RESULTS

Of the 114 patients (group 1, n = 53; group 2, n = 42; group 3, n = 19) screened, seven patients (6% of total; group 1, n = 1; group 2, n = 4; group 3, n = 2) had a alpha1AT level below 80 mg/dL. All had marginally low level (range 57-79 mg/dL), but none had a clinical diagnosis of alpha1AT deficiency. One patient had PiZ- heterozygous phenotype (alpha1AT level 217 mg/dL) while another patient had PiMS heterozygous.

CONCLUSIONS

alpha1AT deficiency is not an important cause of neonatal cholestasis and childhood liver diseases in Malaysian children. In Malaysian children with neonatal cholestasis or other liver diseases, routine assay for alpha1AT phenotype is not recommended if there is no family history of neonatal cholestasis of uncertain aetiology, or if alpha1AT level is above 80 mg/dL.

Protease inhibitor phenotypes and serum alpha-1-antitrypsin levels in patients with COPD: A study from Hong Kong

OBJECTIVE

Many studies have suggested that an imbalance of protease activation and inhibition might result in COPD with emphysema. Levels of alpha-1-antitrypsin (alpha1-AT), the key protease inhibitor, are genetically determined by alleles that present in many phenotypes/subtypes, some of which are associated with deficiency of the protein. We prospectively evaluated the prevalence of the protease inhibitor (Pi) alleles and phenotypes together with the serum alpha1-AT levels in Chinese patients with COPD.

METHODOLOGY

The study population comprised 356 patients with COPD. The male-to-female ratio was 4 : 1 with a mean age of 72.4 years (range 44-93 years). Isoelectric focusing was used for Pi phenotyping/subtyping. The frequencies of Pi alleles and phenotypes were compared with the frequencies in 1085 healthy unrelated Chinese control subjects. The serum alpha1-AT levels were measured by the Cobas Fara assay.

RESULTS

PiZ was not detected. No significant difference in distribution of PiM phenotypes/subtypes between patients with COPD and healthy controls was observed, except for M1M3 and M2M3. There was also a significant difference in the proportion of variant S and F alleles between the disease group and the control population.

CONCLUSION

The low prevalence of deficiency Pi phenotypes/subtypes suggests a lack of contribution of alpha1-AT deficiency to the pathogenesis of COPD in Chinese patients. The strategy of launching an alpha1-AT deficiency detection program among COPD patients, based on the recommendation of the World Health Organization, may not be readily applicable in our local setting.

Distribution of alpha1-antitrypsin PI S and PI Z frequencies in countries outside Europe: a meta-analysis

The objective of the present study was to review published surveys on allelic frequencies S and Z in countries outside Europe to evaluate the validity of the reported data. Studies on the topic, published from 1965 to May 2001, were retrieved using MEDLINE and bibliographic reference consultations. The criteria for the selection of the studies were the following: 1) sample size >or=250 individuals; 2) alpha1-antitrypsin phenotype determination performed by means of crossed antigen-antibody, isoelectric focusing in polyacrylamide gels, or polymerase chain reaction (PCR); 3) PI type determination performed without any previous screening procedure; 4) S and Z 95% CI of the reported outcomes within the limits of a calculated coefficient of variation. Forty-three out of 85 studies comply with the established criteria for being analysed. Worldwide maps of geographical distributions of PI S and PI Z frequencies have been designed by the authors by adding the data provided by these 43 selected studies to the 70 reported in a recent European meta-analysis.

Effect of cigarette smoking on pulmonary function in each phenotype M of alpha-1-protease inhibitor

Human alpha-1-protease inhibitor (alpha-1-Pi) has been known to be a highly polymorphic protein. We hypothesized that antiprotease activity of each phenotype M of alpha 1-protease inhibitor (PiM) might be different among smokers and that a variation of decrease in pulmonary function for a given amount of cigarette smoking might be associated with PiM phenotypes. To test this, we investigated the effect of cigarette smoking on pulmonary function in each PiM phenotype. The serum level of alpha 1-Pi was measured by the turbidimetric immunoassay and the distribution of PiM phenotypes was determined using isoelectric focusing technique in 247 healthy subjects and 20 COPD patients. Serum levels of alpha-1-antitrypsin of healthy and COPD subjects were 205.1 +/- 31.1 and 179.2 +/- 44.4 (+/- SD) mg/dL, respectively (p > 0.01). The frequency of each PiM phenotype in healthy subjects was shown as follows: M1, 0.555; M1M2, 0.328; M2, 0.041; M1M3, 0.057; M2M3, 0.016; M3, 0.004. The difference in the distribution of PiM phenotypes between healthy and COPD subjects was not significant. Single- and multiple-regression analyses showed that the ratio of FEV1 to forced vital capacity (FVC), in which FEV1 is expressed as percentage of FVC, the maximum flow rate at 50% of FVC divided by measured body height (V50/Ht), and the maximum flow rate at 25% of FVC divided by body height (V25/Ht) were closely related to age and that V25/Ht also was related to smoking index. However, PiM phenotype was unrelated to those pulmonary function variables. We conclude that PiM phenotype is not a major determinant of difference in magnitude of pulmonary impairments caused by cigarette smoking in each individual.

Origin of the Koreans: a population genetic study

A population genetic study was undertaken to investigate the origin of Koreans. Thirteen polymorphic and 7 monomorphic blood genetic markers (serum proteins and red cell enzymes) were studied in a group of 437 Koreans. Genetic distance analyses by both cluster and principal components models were performed between Koreans and eight other populations (Koreans in China, Japanese, Han Chinese, Mongolians, Zhuangs, Malays, Javanese, and Soviet Asians) on the basis of 47 alleles controlled by 15 polymorphic loci. A more detailed analysis using 65 alleles at 19 polymorphic loci was performed on six populations. Both analyses demonstrated genetic evidence of the origin of Koreans from the central Asian Mongolians. Further, the Koreans are more closely related to the Japanese and quite distant from the Chinese. The above evidence of the origin of Koreans fits well with the ethnohistoric account of the origin of Koreans and the Korean language. The minority Koreans in China also maintained their genetic identity.