Polymerase chain reaction for detection of the alpha-1-antitrypsin Z allele in chronic liver disease

Systemic nodular panniculitis in a patient with alpha-1 antitrypsin deficiency (PiSS phenotype)

The association of alpha-1 antitrypsin deficiency (PiZ phenotype) with systemic nodular panniculitis has been well documented. Despite reports of cases of systemic nodular panniculitis associated with other alpha-1 antitrypsin deficiency phenotypes, it is still not known if this association is fortuitous rather than causal. We report a case of systemic nodular panniculitis associated with alpha-1 antitrypsin deficiency (PiSS phenotype), with clinico-pathological features similar to those reported in cases associated with the PiZ phenotype.

Hepatic endoplasmic reticulum storage diseases

Endoplasmic Reticulum Storage Diseases (ERSD) represent a novel group of inborn errors of metabolism affecting secretory proteins and resulting in hepatocytic storage and plasma deficiency of the corresponding protein. The hepatocellular storage is due to a molecular abnormality hindering the translocation of the abnormal protein from the rough (RER) to the smooth endoplasmic reticulum (SER). The molecular abnormality is genetically determined; hence it is hereditary, congenital, familial and permanent. The storage is selective and exclusive for the mutant protein and predisposes to the development of chronic cryptogenic liver disease. ERSD include alpha-1-antitrypsin deficiency, fibrinogen storage and alpha-1-antichymotrypsin deficiency. Basically, the diagnosis of ERSD is a morphological one: immunohistochemistry and electron microscopy are essential tools for their identification.

Mutation in codon 713 of the beta amyloid precursor protein gene presenting with schizophrenia

Following reports of mutations of codon 717 in exon 17 of the amyloid precursor protein (APP) gene in early-onset familial Alzheimer's disease, we screened exon 17 for new mutations in presenile dementia. The majority of the 105 patients screened had definite or probable Alzheimer's disease, but we also included atypical cases and some chronic schizophrenics. We identified a single abnormal case--a chronic schizophrenic with cognitive defects. Sequencing revealed a C to T nucleotide substitution which produces an alanine to valine change at codon 713. We were unable to detect the mutation in the remaining members of the original cohort nor in a further 100 chronic schizophrenics and 100 non-demented controls. Nonetheless, the position of the mutation in a critical portion of the APP gene suggests that it may well prove to be pathogenic.

Temperature gradient gel electrophoresis: rapid detection of alpha-1-antitrypsin deficiency carriers

The homozygous state of the alpha-1-antitrypsin (alpha 1AT) deficiency variant Z is associated with severe liver damage in early childhood and progressive lung emphysema in adulthood. A single base transition (G to A in codon 342) in exon V is causing the severe disease. The Glu342 to Lys342 mutation can be detected conventionally by isoelectric focusing (IEF) or on the DNA level by the newly developed method of temperature gradient gel electrophoresis (TGGE). It is the aim of this study to describe the TGGE technique, to compare the results with conventional IEF, and to discuss its efficiency for different diagnostic applications.

The incidence of different cystic fibrosis mutations in the Scottish population: effects on prenatal diagnosis and genetic counselling

We present an analysis of the frequency of 16 different cystic fibrosis (CF) mutant alleles in the Scottish population. Each allele was detected in DNA amplified by the polymerase chain reaction (PCR) either directly on polyacrylamide gels, on agarose gels after restriction enzyme digestion, or by using allele specific oligonucleotides. Among 506 CF chromosomes, of predominantly Scottish origin, the frequencies of the different mutations were delta F508 0.71, G551D 0.05, G542X 0.04, R117H 0.01, 1717-1G----A 0.01, A455E + delta I507 + R553X + R560T + W1282X + 621 + 1G----T combined 0.03, unpublished 0.01, and unknown 0.13. No examples of D110H, R347P, S549N, S549I, or 2566ins AT mutations were found. The relevance of this type of analysis for both prenatal diagnosis and heterozygote screening is discussed.

Identification of PiZ gene products in liver tissue by a monoclonal antibody specific for the Z mutant of alpha 1-antitrypsin

Globular inclusions of abnormal alpha 1-antitrypsin (AAT) in the rough endoplasmic reticulum of hepatocytes is a characteristic feature of AAT deficiency of the PiZ phenotype. It is also seen in some rare M-like Pi types (including M-Cagliari) having low plasma AAT levels and M-like mobility on isoelectric focusing. In this report the ability of a monoclonal antibody (ATZ 11) raised against PiZ hepatocytic AAT to identify AAT inclusions by immunohistochemical techniques is evaluated. The antibody was found to specifically and selectively identify the PiZ gene products in hepatocytes, but not M-Cagliari AAT. Application of the method thus allows distinction of PiZ gene carriers from PiM-like subjects in the absence of serum protein analysis.

Molecular genetics of chronic liver diseases

The molecular genetics of five common single gene and one polygenic chronic liver disease is discussed. In two of the single gene disorders, alpha 1-antitrypsin deficiency and cystic fibrosis, the gene responsible is now known and the repertoire of different mutations underlying the disease is being defined. In the other three single gene defects (haemochromatosis, polycystic liver disease and Wilson's disease) the chromosomal location of the disease allele is known. It is anticipated that recombinant DNA techniques will enable the genes responsible for these diseases to be cloned in the near future, thus allowing the biochemical abnormalities to be defined through reverse genetics. In many chronic liver diseases the relative contribution of genetic and environmental factors remains unclear. Evidence suggests there is a definite genetic component in predisposition to alcoholic cirrhosis; the role of putative candidate genes is discussed. It is hoped that the definition of a genetic locus linked to alcoholic cirrhosis will ultimately teach us more about the basic pathogenesis of this disease.