Pi Ecincinnati: A new alpha1-antitrypsin allele in three negro families

Summary Serum specimens of three unrelated black males had an unusual alpha-1-antitrypsin phenotype, designated Pi Ecincinnati because of its electrophoretic mobility. Family studies indicated that the new phenotype was the expression of an alpha-1-antitrypsin allele, labeled Pi ^Ecincinnati     

Pi Zpratt : A new alpha1-antitrypsin allele in an American negro family

Summary A low-power laser-UV microbeam of wave-length 257 nm was used for microirradiation of a small part of the nucleus of Chinese hamster cells. Following fixation in interphase or in the subsequent metaphase indirect immunofluorescent staining was performed with antiserum to photoproducts of DNA treated with far UV light.The results show that antibodies specific for UV-irradiated DNA can be used for a direct detection of laser-UV microirradiation-induced DNA photolesions. The potential usefulness of this method for investigation of the spatial arrangement of chromosomes in the interphase nucleus is discussed.     

alpha1-antitrypsin: common subtypes of Pi M.

More than 20 different alleles are so far known at the Pi locus, corresponding to a total variant phenotype frequency of about 10% in most western Europeans. The common phenotype Pi M constitutes the remaining major group. Now it has been possible to identify three subtypes M1, M1M2 and M2, corresponding to the gene products of two common alleles PiM1 and PiM2, segregating as autosomal codominant alleles. Preliminary gene frequencies are reported for eight populations, the PiM2 frequency varying from 0.20 in Maris (USSR) to 0.02 in Bantus (Kenya).     

A new allele of human alpha1-antitrypsin: PiNhampton.

A new allele of alpha1AT is described. By isoelectric focusing, the microheterogeneous pattern of the variant was similar to but more cathodal than that of Pi N. This allele has therefore been tentatively designated PiNhampton(Nham). Further examination revealed that the minor bands of Nham are indistinguishable from the major bands of Z by isoelectric focusing, and a careful family study was necessary to clearly define the proband's phenotype. Pi Nham was found in association with M1, S, and Z, but to date its possession is not apparently related to clinical disorders or reduced serum levels of alpha1AT.     

Characterization of the molecular basis of the alpha 1-antitrypsin F allele.

alpha 1-Antitrypsin (alpha 1AT), the major serum inhibitor of neutrophil elastase, is a highly polymorphic serum protein associated with characteristic isoelectric-focusing (IEF) patterns for most variants. To characterize the molecular basis of the anodal F variant, the DNA sequence of the coding exons of an FZ individual was determined. The F allele differed from the normal M1(Val213) alpha 1AT allele by a single nucleotide transversion of cytosine to thymidine, which results in the amino acid substitution Arg223 CGT----Cys TGT. Inheritance of the F mutation was confirmed by family analysis using allele-specific amplification. In the context that the normal alpha 1AT molecule has only one cysteine residue, a mutation resulting in the addition of a second cysteine may influence the three-dimensional form of the protein and/or permit interaction with other plasma proteins with free-SH groups and may be responsible for the observation that the major F alpha 1AT bands often migrate as doublets in IEF gels.     

New variants of alpha 1-antitrypsin: comparison of Pi typing techniques.

Four new rare inherited variants (Pi types) of alpha 1-antitrypsin (alpha 1-protease inhibitor) are described. Each variant has been compared with previously reported genetic variants by several techniques used for Pi typing: isoelectric focusing in polyacrylamide gel, starch gel electrophoresis, and agarose gel electrophoresis. Some variants are identical or very similar by one technique but can be clearly distinguished by another technique. Crossed immunoelectrophoresis and gel immunofixation have been used to identify the gel bands as alpha 1-antitrypsin.     

Pi Mheerlen,a Pi M allele resulting in very low a 1-antitrypsin serum levels

Summary A patient with pulmonary emphysema is described, who had a very low ₁-antitrypsin serum concentration (2% of normal). After isoelectric focusing and staining, the patient's serum revealed no visible ₁-antitrypsin bands. Immunofixation, following isoelectric focusing, gave a banding pattern identical to that of a normal M type. The existence of this deficient M-allele was confirmed by family studies. Low ₁-antitrypsin concentrations, due to the presence of the deficient allele, were coupled with low serum antitrypsin activities.     

Alpha 1-antitrypsin Null(isola di procida): an alpha 1-antitrypsin deficiency allele caused by deletion of all alpha 1-antitrypsin coding exons.

alpha 1-Antitrypsin (alpha 1AT) deficiency, a common hereditary disorder responsible for emphysema in Caucasians of northern European descent, is caused by single base substitutions, deletions, or additions in the seven exons (IA-IC and II-V), of the 12.2-kb alpha 1AT gene located on chromosome 14 at q31-32.3. Of the five known representatives of the "null" group of alpha 1AT-deficiency alleles (alpha 1AT genes incapable of producing alpha 1AT protein detectable in serum) evaluated at the gene level, all result from mutations causing the formation of stop codons in coding exons of the alpha 1AT gene. The present study identifies an alpha 1AT allele (referred to as "Null(isola di procida")) caused by complete deletion of the alpha 1AT coding exons. The Null(isola di procida) allele was identified in an individual with heterozygous inheritance of M(procida) (an allele associated with alpha 1AT deficiency) and a null allele. Although results of karyotypic analysis were normal, quantification of the copies of alpha 1AT genes in this individual revealed that the index case had only half the normal copies of alpha 1AT genes. Cloning and mapping of the Null(isola di procida) gene demonstrated a deletion of a 17-kb fragment that included exons II-V of the alpha 1AT structural gene. As a consequence of the deletion, the normal noncoding exons (IA-IC) were followed by exons II-V of the downstream alpha 1AT-like gene. Sequence analysis of the deletion demonstrated a 7-bp repeat sequence (GAGGACA) both 5' to the deletion and at the 3' end of the deletion, a 4-bp palindromic sequence (ACAG vs. CTGT) bracketing the deletion, and a novel inserted 4-bp sequence (CCTG) at the breakpoint, suggesting that the mechanism of the deletion may have been "slipped mispairing."     

Genetic variants of serum alpha1-antitrypsin (Pi types) in Portuguese.

The results of Pi typing on 330 Portuguese from the area of Lisbon are reported. We found six phenotypes and four alleles out of the 24 described in the literature. The allele PiM is the most frequent as in other populations, PiS shows a high frequency (0.1152), and PiF is absent, which agrees satisfactorily with former studies carried out in Spain. These results are compared with others and the entity of the Iberian population is evoked.     

In-frame single codon deletion in the Mmalton deficiency allele of alpha 1-antitrypsin.

A deficiency of the plasma protease inhibitor alpha 1-antitrypsin (alpha 1AT) is usually a consequence of the PI*Z allele. Mmalton is another deficiency allele which, like Z alpha 1AT, is associated with hepatocyte inclusions and impaired secretion. We report here the sequence of the PI Mmalton allele, which contains a 3-bp deletion coding for one of two adjacent phenylalanine residues (amino acid 51 or 52 of the mature protein). Using oligonucleotide hybridization of polymerase chain reaction-amplified DNA, we have demonstrated cosegregation of the PI Mmalton protein and the 3-bp deletion in the family in which this allele was originally described and in three other, unrelated kindreds. This deletion is found exclusively in PI Mmalton alleles and not in the normal M2 alleles from which, to judge on the basis of haplotype data, the Mmalton mutation must have been derived. In polyacrylamide isoelectric focusing (PIEF) gels, the isoelectric point of Mmalton is only slightly more cathodal than M2, a finding consistent with the loss of a single uncharged amino acid. To judge on the basis of X-ray crystallography data for the normal alpha 1AT protein, the deletion of aa 51/52 would shorten one strand of the beta sheet, B6, apparently preventing normal processing and secretion.     

PiT: A new allele in the alpha1-antitrypsin system

Summary In a genetic investigation of the population in Hessen, Germany, we found a family with a new, rare allele in the Pi system (₁-antitrypsin). According to electrophoretic analysis and isoelectric focusing patterns, it is designated Pi ^T. A pedigree study suggests autosomal codominant inheritance. The serum concentration of six heterozygous carriers of this allele (phenotype M1T or M2T) revealed normal ₁-antitrypsin levels.     

The purification and properties of human alpha1-antitrypsin (alpha1-antiprotease), variant Z.

After three stages of preliminary purification, variant Z was chromatographed on a DEAE-cellulose column. Upon elution with a linearly increasing concentration of NaCl, variant Z was recovered in two separate peaks, the first of which contained 81% and the second 19% of the total. The preparation corresponding to the first peak was homogeneous by various criteria. The trypsin and chymotrypsin inhibiting capacities and the specific antigenic activity of the preparation were nearly the same as those of an authentic sample of variant M. Variant Z contained 8 or 9 more gycine residues than variant M, but no appreciable difference was found between their carbohydrate contents. By analytical isoelectrofocusing the isoinhibitors of purified variant Z overlapped with those in the plasma of the donor and were cathodal to, but partially overlapped with purified variant M. After desialysation, the overlap between the different variants became complete, but variant Z contained a larger proportion of cathodal and smaller proportion of anodal components than variant M. Both variants formed five distinct isoinhibitor-protease complexes after incubation with trypsin and chymotrypsin and the corresponding complexes in the different variants completely coincided.     

Characterization of the gene and protein of the common alpha 1-antitrypsin normal M2 allele.

The normal M2 variant of alpha 1-antitrypsin (alpha 1AT) was cloned from a genomic DNA library of an individual homozygous for this allele. Sequencing of all coding exons of the M2 gene revealed it was identical to the common M1(Val213) gene except for two bases (M1(Val213) CGT Arg101, M2 CAT His101; M1(Val213) GAA Glu376 M2 GAC Asp376). Analysis of the sequence of the M1(Val213) and M2 genes around residue 101 revealed the M1 Arg101----M2 His101 caused a loss of the cutting site for the restriction endonuclease RsaI. Using this enzyme, as well as 19-mer oligonucleotides probes centered at residues 101 and 376, evaluation of genomic DNA from 22 M1 alleles and 14 M2 alleles revealed that residue 101 was Arg in all M1 alleles and His in all M2 alleles, while residue 376 was Glu in all M1 alleles and Asp in all M2 alleles. Despite the differences in sequence at two amino acids, the M1(Val213) and M2 proteins function similarly as assessed by quantification of the association rate constant of each for their natural substrate neutrophil elastase. In the context that there are two mutations separating the M1(Val213) and M2 alleles, it is likely that there is another alpha 1AT variant that was an intermediate in the evolution of these genes.     

Aggregation of plasma Z type alpha 1-antitrypsin suggests basic defect for the deficiency

The abnormal type of alpha 1-antitrypsin, PI (protease inhibitor) type Z, is associated with inclusion bodies in the liver, which contain non-secreted alpha 1-antitrypsin. Our studies show that Z protein has an inherent tendency to aggregate, even in plasma. Depending upon conditions, from 15 to 70% of the Z protein in plasma was in a high-Mr form, compared with 1.5% of M type alpha 1-antitrypsin. The high-Mr complex in plasma cannot be disaggregated using Triton X detergent or reducing conditions. This increased tendency to aggregate can be explained by the mutation affecting, tertiary structure and salt bridge formation in Z protein. We have observed this same tendency to aggregate for Mmalton alpha 1-antitrypsin, a rarer variant also associated with a plasma deficiency.