Linkage of cystic fibrosis to the pro alpha 2(I) collagen gene, COL1A2, on chromosome 7

Identifying sarcomere gene mutations in hypertrophic cardiomyopathy: a personal history

This review provides an historical and personal perspective on the discovery of genetic causes for hypertrophic cardiomyopathy (HCM). Extraordinary insights by physicians who initially detailed remarkable and varied manifestations of the disorder, collaboration among multidisciplinary teams with skills in clinical diagnostics and molecular genetics, and hard work by scores of trainees solved the etiologic riddle of HCM and unexpectedly demonstrated mutations in sarcomere protein genes as the cause of disease. In addition to celebrating 20 years of genetic research in HCM, this article serves as an introductory overview to a thematic review series that will present contemporary advances in the field of hypertrophic heart disease. Through the continued application of advances in genetic methodologies, combined with biochemical and biophysical analyses of the consequences of human mutations, fundamental knowledge about HCM and sarcomere biology has emerged. Expanding research to elucidate the mechanisms by which subtle genetic variation in contractile proteins remodel the human heart remains an exciting opportunity, one with considerable promise to provide new strategies to limit or even prevent HCM pathogenesis.

Serum paraoxonase-1 in chronic alcoholics: relationship with liver disease

OBJECTIVES

To investigate the relationship between serum paraoxonase-1 and liver damage in chronic alcoholic patients. To assess the diagnostic accuracy of paraoxonase-1 plus standard biochemical tests in the assessment of liver damage in alcoholics.

DESIGN AND METHODS

We studied 328 chronic alcoholics and 368 healthy individuals.

RESULTS

Paraoxonase-1 activity was decreased and the concentration was increased in alcoholics (P<0.001). The enzyme activity was correlated with albumin (r=0.45; P<0.001) and prothrombin time (r=0.49; P<0.001). Addition of paraoxonase-1 activity measurement to a battery of biochemical tests increased the sensitivity in differentiating between patients and controls up to 96.6% but did not improve the sensitivity in differentiating between subgroups of alcoholics.

CONCLUSIONS

Paraoxonase-1 was related to the severity of alcoholic liver disease. Its measurement was useful in discriminating between patients and healthy subjects, but did not add any valuable information in subgroups of alcoholics.

Paraoxonase-1 is associated with oxidative stress, fibrosis and FAS expression in chronic liver diseases

BACKGROUND/AIMS

We previously reported that paraoxonase-1 activity measurement may be useful for the evaluation of liver diseases. Because oxidative stress plays a role in liver apoptosis, and lipid peroxides are hydrolyzed by paraoxonase-1, we have extended our studies to explore the relationships between this enzyme and oxidative stress, fibrosis and apoptosis.

METHODS

We measured paraoxonase-1 activity and concentration, soluble FAS concentration, serum fibrosis markers, and total peroxides in a group of patients with minimal hepatic changes (n=25), chronic hepatitis (n=51), or liver cirrhosis (n=17). We also measured the Knodell activity index in liver biopsies and performed FAS and PON1 immunostaining.

RESULTS

Patients with liver diseases showed an increase in soluble FAS, fibrosis markers and paraoxonase-1 concentrations, as well as a decrease in PON1 activity. Paroxonase-1 activity and concentration were correlated with soluble FAS (r=-0.43, P<0.001 and r=0.27, P=0.007, respectively). Paraoxonase-1 concentration showed a significant inverse association with FAS immunostaining (P=0.013) and a direct association with PON1 immunostaining (P<0.001).

CONCLUSIONS

These results suggest an active role of PON1 in the regulation of oxidative stress, fibrosis and hepatic cell apoptosis in chronic liver diseases.

Cystic fibrosis and Helicobacter pylori gastritis, megaloblastic anaemia, subnormal mentality and minor anomalies in two siblings: a new syndrome?

Two siblings of consanguineous Arab parents were found to have cystic fibrosis and gastritis associated with Helicobacter pylori, folate deficiency megaloblastic anaemia, subnormal mentality and minor anomalies. The association of H. pylori and megaloblastic anaemia has not been described in patients with cystic fibrosis. H. pylori infection and gastritis is probably more common in patients with cystic fibrosis than appreciated. We believe that the constellation of features in the two sibs represent a possible new autosomal recessive cystic fibrosis-like syndrome.

Abnormal protein translocation as the elusive cause of cystic fibrosis: an hypothesis

Despite the recent rapid advances in isolation of the abnormal gene responsible for cystic fibrosis, there remains the need to explain the mechanism by which a single gene mutation causes the widespread clinical effects seen in this disease. Careful review of the otherwise unexplained abnormalities of cystic fibrosis from the perspective of cell biology reveals the following common features: (1) all these abnormalities involve proteins which are either (A) inserted into cell membranes in the RER and arrested after partial translocation or (B) inserted into RER membranes and fully translocated to be compartmentalized away from the cytosol in secretory vacuoles, lysosomes or peroxisomes; (2) all the involved proteins have minor abnormalities in their physicochemical properties or activity functions; (3) none of the involved proteins are missing or totally deficient in function; (4) final compartmentalization of the involved proteins is unaffected. These observations have directed our attention to the process by which most proteins are inserted into and translocated across lipid bilayer membranes, namely the signal peptide mechanism. This mechanism, not previously examined in cystic fibrosis, is reviewed in detail. Of the major proteins controlling signal peptide translocation, deficiencies in the function of signal peptidase activity appear most capable of causing the effects seen in cystic fibrosis.

Progress towards cloning the cystic fibrosis gene

Genetic linkage analysis with polymorphic DNA markers (restriction fragment length polymorphisms: RFLPS) has allowed the assignment of the cystic fibrosis (CF) locus to the long arm of chromosome 7, within the region of band q31. Two of these markers, MET and D7S8, are tightly linked to the disease locus. Although recent data suggest that they are located on opposite sides of CF, the two can be separated by as much as 5 centimorgans. To obtain a better description of the CF locus and, eventually, to identify the affected gene, additional DNA markers are required to connect MET and D7S8, physically. We have screened the flow-sorted chromosome-7-specific library and thus far isolated 28 new probes from the 7q31 region by DNA hybridization analysis that uses a series of somatic cell hybrids containing various portions of human chromosome 7. Together with the previously identified markers, MET, D7S8, D7S13 and D7S16, these new markers should provide a fine genetic and physical map for the chromosomal region surrounding CF. DNA segments can then be sequentially cloned by chromosome walking from points closest to the CF locus and examined for genes that are preferentially expressed in tissues known to be affected in the disease.

Genetic markers on chromosome 7

Chromosome 7 is frequently associated with chromosome aberrations, rearrangements, and deletions. It also contains many important genes, gene families, and disease loci. This brief review attempts to summarise these and other interesting aspects of chromosome 7. With the rapid accumulation of cloned genes and polymorphic DNA fragments, this chromosome has become an excellent substrate for molecular genetic studies.

Plasminogen activator inhibitor type 1 gene is located at region q21.3-q22 of chromosome 7 and genetically linked with cystic fibrosis

The regional chromosomal location of the human gene for plasminogen activator inhibitor type 1 (PAI1) was determined by three independent methods of gene mapping. PAI1 was localized first to 7cen-q32 and then to 7q21.3-q22 by Southern blot hybridization analysis of a panel of human and mouse somatic cell hybrids with a PAI1 cDNA probe and in situ hybridization, respectively. We identified a frequent HindIII restriction fragment length polymorphism (RFLP) of the PAI1 gene with an information content of 0.369. In family studies using this polymorphism, genetic linkage was found between PAI1 and the loci for erythropoietin (EPO), paraoxonase (PON), the met protooncogene (MET), and cystic fibrosis (CF), all previously assigned to the middle part of the long arm of chromosome 7. The linkage with EPO was closest with an estimated genetic distance of 3 centimorgans, whereas that to CF was 20 centimorgans. A three-point genetic linkage analysis and data from previous studies showed that the most likely order of these loci is EPO, PAI1, PON, (MET, CF), with PAI1 being located centromeric to CF. The PAI1 RFLP may prove to be valuable in ordering genetic markers in the CF-linkage group and may also be valuable in genetic analysis of plasminogen activation-related diseases, such as certain thromboembolic disorders and cancer.

Diagnosis of genetic disease using recombinant DNA. Supplement

Recombinant DNA methodology has greatly increased our knowledge of the molecular pathology of the human genome at the same time as providing the means to diagnose inherited disease as the DNA level. We present here a list of recent reports of both direct and indirect analysis of human inherited disease which is intended to serve as a guide to current molecular genetic approaches to diagnostic medicine.