Molecular analysis of the Pi*Z allele in patients with liver disease

Prevalence of α-1-antitrypsin gene mutations in Saudi Arabia

BACKGROUND/AIM

α-1 antitrypsin (AAT) deficiency results from mutations of the protease inhibitor (PI). The AAT gene is mapped on chromosome 14 and has been associated with chronic liver disease and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

To determine the frequency of AAT mutations on S and Z carrier alleles in healthy Saudi individuals from Qassim Province in Saudi Arabia.

PATIENTS AND METHODS

A total of 158 healthy, unrelated participants from Qassim Province were recruited. They were genotyped for the two AAT-deficiency alleles, PIFNx01S and PIFNx01Z, using polymerase chain reaction, with primers designed throughout to mediate site-directed mutagenesis.

RESULTS

Of the 158 subjects, 11.39% were carriers for the S mutation (i.e., had the MS genotype), whereas 2.53% were carriers for the Z mutation (i.e., had the MZ genotype). The SZ genotype was present in 3.8% of subjects, while the homozygous genotype SS was present in 1.9% of subjects. No subjects showed the ZZ mutant genotype. Accordingly, frequency of the mutant S and Z alleles of AAT gene was 9.49% and 3.19%, respectively.

CONCLUSION

The results obtained showed a high prevalence of the AAT deficiency allele in the Saudi population. This probably warrants adoption of a screening program for at-risk individuals, so that they might initiate adequate prophylactic measures.

High prevalence of alpha-1-antitrypsin heterozygosity in children with chronic liver disease

OBJECTIVE

Alpha-1-antitrypsin (A1AT) deficiency is the most common genetic cause of liver disease in children; however, the role of polymorphic heterogeneity in the A1AT gene as a modifier of other forms of pediatric liver disease is not clear. We hypothesized that non-M A1AT allele variants are more common in children with chronic liver disease than in the general population.

METHODS

A retrospective, single-center study was performed in which A1AT phenotypes were obtained by reviewing charts of children with chronic liver disease. Chi-square analysis was used to compare allele frequencies in the population of children with liver disease with published epidemiologic data and to compare allele frequencies among disease subgroups.

RESULTS

The frequency of A1AT Z and other alleles was increased in children with chronic liver disease (n = 241) when compared with the published reference database (P < 0.001). This increase remained significant when the population was divided into disease subsets: biliary atresia (n = 67) and other liver disease (n = 174) (P < 0.001 for both). Among children with biliary atresia referred for liver transplant evaluation, the presence of a non-M allele was associated with a lower mean age at transplant listing than the MM phenotype (235 vs 779 days, P = 0.036) and more frequent loss of native liver by 24 months of age (90% vs 65%, P = 0.04).

CONCLUSIONS

A1AT non-M alleles are more frequent in children with chronic liver disease than in the general population. We speculate that these non-M alleles may act as genetic modifiers in pediatric liver disease in general and modulate disease progression in children with biliary atresia in particular.

Alpha-1-antitrypsin associated panniculitis: the MS variant

Over 90 mutant alleles of the alpha-1-antitrypsin (AAT) gene are recognized and classified by mobility on an acid starch gel. The four major categories include: F=fast, M=medium, S=slow, Z=very slow. Among 41 reported cases of AAT panniculitis, most have the ZZ phenotype with AAT levels below normal. We report two cases of AAT panniculitis with MS phenotype and normal AAT levels. In addition, we review the pathophysiology, epidemiology, and extracutaneous manifestations of AAT disease and propose a diagnostic algorithm for ulcerative panniculitis. A 42-year-old man presented with a solitary plaque on the left thigh exacerbated by trauma or excessive activity. The lesion frequently suppurated with a yellowish oily material. Twenty years before, he had fractured his left femur which was repaired with a metal plate. X-rays, histology with special stains for organisms, and cultures were negative. AAT phenotype was MS and AAT value was normal. A 43-year-old woman presented with multiple plaques on the proximal extremities which suppurated with exercise or trauma. AAT phenotype was MS and AAT level was normal. Histologic exam for both patients showed a dense neutrophilic infiltrate with septal and lobular panniculitis and areas of necrobiosis in the lower reticular dermis.

Factors associated with advanced liver disease in adults with alpha1-antitrypsin deficiency

BACKGROUND & AIMS

Alpha 1 -antitrypsin deficiency (AAT) is an autosomal recessive disease that affects 1 in 2500 persons and might lead to cirrhosis. Our study aim was to characterize the liver disease in AAT and identify factors associated with advanced liver disease.

METHODS

A cohort of the Alpha-1 Foundation Registry who reported liver disease was surveyed with a liver disease questionnaire to obtain information related to liver disease, liver transplantation, and AAT phenotype.

RESULTS

One hundred sixty-five of the 2175 participants in the registry reported a history of jaundice or liver disease, and 139 (84.2%) completed the questionnaire. Of these, 71.3% were PiZZ, 18.0% were PiMZ, and 5.7% did not know their phenotype. Analysis of 104 participants with a known age of diagnosis included 30 participants diagnosed with liver disease before 18 years, of whom 15 had advanced liver disease defined as liver transplantation or listed for liver transplantation. No differences in age, age at diagnosis, gender, race, phenotype, or infant jaundice were identified. Seventy-four participants were diagnosed after age 18 years, of whom 25 had advanced liver disease. In this group, advanced liver disease was associated with male gender ( P = .006) and a greater mean body mass index ( P = .01), but not with race, Pi phenotype, infant jaundice, diabetes, or hypercholesterolemia. Viral hepatitis was more frequently reported in the nontransplant group (34.7% vs 8.0%, P = .01), and the mean daily alcohol use was significantly greater in this group ( P = .04).

CONCLUSIONS

Our results suggest that male gender and obesity but not alcohol or viral hepatitis predispose to advanced liver disease in adults with AAT.

Health implications of α1-antitrypsin deficiency in Sub-Sahara African countries and their emigrants in Europe and the New World

PURPOSE

To determine the frequencies of the protease inhibitor (PI) deficiency alleles of alpha1-antitrypsin deficiency (AAT Deficiency) in indigenous populations in 12 countries in Sub-Sahara Africa because of their potential impact on the health in these populations with regard to the high risk for development of liver and lung disease. In addition, to discuss the unique susceptibility of these populations and emigrants to Europe and the New World to the adverse health effects associated with exposure to environmental microbes, chemicals, and particulates.

METHODS

Detailed statistical analysis of the 24 control cohort databases from genetic epidemiological studies by others were used to estimate the allele frequencies and prevalence for the two most common deficiency alleles PIS and PIZ and to estimate the numbers at risk in each of the local Sub-Sahara populations as well as those who have emigrated from these countries to Europe and the New World.

RESULTS

The present study has provided evidence for the presence of both PIS and PIZ in the general populations of Nigeria, Republic of South Africa, and Somalia, the PIS allele in Angola, Botswana, Cameroon, Mozambique, Namibia, and the Republic of Congo, and only the PIZ allele in Mali.

CONCLUSION

AAT Deficiency is found in both the Black and "Colored" populations in many of the Sub-Sahara countries in Africa, providing evidence for the presence of AAT Deficiency in such populations in Europe and in the New World. Such populations should be screened for AAT Deficiency and made aware of their unique susceptibility to exposure to chemical and particulate agents in the environment.

Genetic epidemiology of alpha-1 antitrypsin deficiency in North America and Australia/New Zealand: Australia, Canada, New Zealand and the United States of America

Alpha-1-antitrypsin deficiency (AAT deficiency) is one of the most common serious hereditary disorders in the world, as its affects all major racial subgroups worldwide, and there are an estimated 120.5 million carriers and deficient subjects worldwide. This genetic disease is related to susceptibility for development of jaundice in infants, liver disease in children and adults and pulmonary emphysema in adults. Moreover, AAT deficiency carrier phenotypes (PiMS and PiMZ) and deficiency allele phenotypes (PiSS, PiSZ and PiZZ) are suspected to predispose subjects to a variety of other adverse health effects. Because there is a limited database on the number of individuals affected by this disease worldwide, we have collected data on control cohorts in genetic epidemiological studies published on case-control studies in the peer-reviewed literature worldwide. Based on these data, we estimated the numbers of carriers and deficiency allele combinations for the two most common defective alleles, namely PiS and PiZ in 58 countries worldwide. The present paper focuses on the distribution of the PiS and PiZ deficiency alleles in Australia, Canada, New Zealand and the United States of America. A total of 31,042,232 individuals at risk for adverse health effects have been calculated in these four countries: 2,144,158 in Australia, 3,258,564 in Canada, 430,922 in New Zealand and 24,909,548 in the United States of America. The prevalences for all five phenotypic classes of AAT deficiency in each of these countries is as follows: Australia 1 out of 8.9, Canada 1 out of 9.8, New Zealand 1 out of 8.5 and the United States of America 1 out of 11.3. The geographical distribution of individual control cohorts and estimates of the numbers of carriers and deficiency allele phenotypes in each of these four countries are given in individual tables.

Genetic epidemiology of alpha-1 antitrypsin deficiency in southern Europe: France, Italy, Portugal and Spain

Alpha-1-antitrypsin deficiency (AAT deficiency) is one of the most common serious hereditary disorders in the world because it affects all major racial subgroups worldwide and there are at least 120.5 million carriers and deficient subjects worldwide. This genetic disease is related to a high risk for development of jaundice in infants, liver disease in children and adults, and pulmonary emphysema in adults. Moreover, AAT-deficiency carrier phenotypes (PiMS and PiMZ) and deficiency-allele phenotypes (PiSS, PiSZ, and PiZZ) are suspected to make subjects susceptible to a variety of other adverse health effects. As there is a limited database on the number of individuals affected by this disease worldwide, the authors of the present report collected data on control cohorts in genetic epidemiological studies published in the peer-reviewed literature worldwide. The data collected were used to estimate the numbers of carriers and deficiency-allele combinations for the two most common defective alleles, namely PiS and PiZ, in over 58 countries worldwide. The present report focuses on the distribution of the PiS and PiZ deficiency alleles in France, Italy, Portugal, and Spain. The total number of individuals at risk for adverse health effects were as follows: 9, 101, 739 in France; 4, 289, 566 in Italy; 2, 659, 241 in Portugal; and 8, 903, 773 in Spain. The geographical distribution of individual control cohorts and estimates of the numbers of carriers and deficiency-allele phenotypes in each of these four southern European countries are shown in individual tables and maps. This report will be followed by other reports on the remaining countries in Europe, as well as worldwide.

Worldwide racial and ethnic distribution of alpha1-antitrypsin deficiency: summary of an analysis of published genetic epidemiologic surveys

STUDY OBJECTIVES

Alpha1-antitrypsin (AAT) deficiency is a genetic disease that is widely known in Europe as a disease of white individuals, who, along with their descendants in other parts of the world, are at the highest risk for liver and/or lung disease. There is a limited database of individuals affected by this disease worldwide. It has been estimated, for example, that there are 70,000 to 100,00 individuals affected in the United States, with comparable numbers in Europe.

STUDY DESIGN

Genetic epidemiologic studies in the peer-reviewed literature have been used in an exploratory study to estimate the number of carriers and the number of those individuals who are homozygous or heterozygous for the two most common defective alleles for AAT deficiency in 58 individual countries. The total country database of 373 control cohorts has been combined to estimate the numbers of carriers and deficiency allele combinations for PiS and PiZ in 11 geographic regions and worldwide. The study was designed to be illustrative rather than comprehensive, and more detailed publication of the enormous database developed in this exploratory study is planned.

CONCLUSIONS

The database presented indicates that in a total population of 4.4 billion in the countries surveyed worldwide, there are at least 116 million carriers (PiMS and PiMZ) and 3.4 million deficiency allele combinations (PiSS, PiSZ, and PiZZ). Furthermore, this database demonstrates that AAT deficiency is found in various populations of African blacks, Arabs and Jews in the Middle East, whites in Australia/New Zealand, Europe, and North America, central Asians, far east Asians, and southeast Asians. These data demonstrate that AAT deficiency is not just a disease of whites in Europe, but that it affects individuals in all racial subgroups worldwide. In addition, AAT deficiency may be one of the most common serious hereditary disorders in the world.

Inherited metabolic disease

The elucidation of metabolic pathways and the genetic basis for diseases of the liver continues to increase our understanding of disease pathogenesis and advance treatment options. This selective review covers a wide range of subjects, from the identification of novel proteins and the importance of specific transport pathways to phenotypic expression of disease and management of acute liver failure. Three selected disorders--Wilson disease, genetic hemochromatosis and other hereditary iron overload disorders, and alpha(1)-antitrypsin disease--are the focus of this review.