Search PubMed⌕ Search

Biomedical subjects

M Shohat

Publications and source records attributed to M Shohat.

At least 127 records · Page 7Linked to original sources
PubMed1992

Biochemical characterization of a pedigree with mitochondrially inherited deafness.

A large kindred with a predicted 2-locus inheritance of sensorineural deafness, caused by the combination of a mitochondrial and an autosomal recessive mutation, was examined at the biochemical level. Because of the mitochondrial inheritance of this disease, we looked for defects in the oxidative phosphorylation Complexes I, III, IV, and V, the 4 enzymes that include all of the 13 mitochondrially encoded polypeptides. Biosynthetic labelling of lymphoblastoid cells from deaf patients, unaffected siblings, and an unrelated control showed no difference in size, abundance, rate of synthesis, or chloramphenicol-sensitivity of the mitochondrially encoded subunits. Since overall mitochondrial protein synthesis appears normal, these results suggest that the mitochondrial mutation is unlikely to be in a tRNA or rRNA gene. No change in enzymatic levels was seen in lymphoblastoid mitochondria of the deaf patients, compared to unaffected sibs and controls, for Complexes I and IV. Both affected and unaffected family members showed an increase in Complex III activity compared to controls, which may reflect the mitochondrial DNA shared by maternal relatives, or be due to other genetic differences. Complex V activity was increased in deaf individuals compared to their unaffected sibs. Since the family members share the presumptive mitochondrial mutation, differences between deaf and unaffected individuals likely reflect the nuclear background and suggest that the autosomal recessive mutation may be related to the increase in Complex V activity. These biochemical studies provide a guide for sequence analysis of the patients' mitochondrial DNA and for linkage studies in this kindred.

Cell Line, Transformed↗
PubMed1992

Twin studies in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is a genetic disease characterized by recurrent short episodes of fever, accompanied by peritonitis, pleuritis, or arthritis. The disease is almost completely ethnically restricted to patients of Mediterranean descent--Sephardic Jews, Armenians, Anatolian Turks, and Arabs. Although many family studies have been performed, no twin study has been reported as yet. We studied 21 di- and monozygotic twin sets, identified among the 1,943 FMF patients in our registry. Full concordance was observed in all the 10 monozygotic twin sets. In the 11 dizygotic twins, concordance for FMF disease was found in only 3 pairs. Variability in the clinical manifestations and degree of severity have been noted within twins. These findings provide definitive evidence for the genetic cause of FMF. They also support the single gene autosomal recessive model, and provide support for the contention that the lower observed than expected incidence found in FMF is due to genetically affected but clinically undiagnosed patients.

Adolescent↗
PubMed1992

Familial Mediterranean fever: analysis of inheritance and current linkage data.

Familial Mediterranean fever (FMF) is a genetic disorder characterized by recurrent attacks of fever and inflammation of serosal surfaces. Unlike many mendelian disorders, the mode of transmission has been subject to some controversy as segregation analysis studies have always demonstrated fewer "observed" than "expected" affected individuals. Despite efforts to map the gene causing FMF, no definite linkage has been yet identified. This review analyses the epidemiologic and genetic characteristics in order to evaluate critically the inheritance of the disease and provide a perspective on the current biochemical and molecular genetic studies whose aim is to locate the gene for this disease.

Amyloidosis↗
PubMed1992

Marked parental consanguinity as a cause for increased major malformations in an Israeli Arab community.

It is common among Israeli Arabs who live in the villages to prefer consanguineous marriages, particularly among first cousins. In addition, such villages are populated by a few (less than 20) original families, and inter-family/inter-village marriages are infrequent. The purpose of this study was to examine the consequences of such "consanguinity" in Taibe, a large Arab village, 30 km from Tel Aviv. Six hundred ten families were prospectively ascertained through infants who were routinely seen in the local "Well Baby Clinics." A significant increase in the incidence of major malformations was noted in relation to the closeness of the parental relationship. For the index cases group the prevalence of individuals with major malformations were 5.8% in the product of inter-village marriages, 8.3% in the intra-village non-related matings, 15.1% in the distant consanguineous group, and up to 15.8% in the progeny of first-cousin marriages (P less than 0.001). In the siblings of these index cases, the frequency of major malformations was 4.3%, 4.5%, 10.5%, and 10.3%, respectively. Analysis of the major malformations by each body system showed the same trend. The study demonstrates a marked high rate of consanguineous marriages, whose effect leads to a marked increase in major malformations and thus a prominent public health problem in such villages. This requires a unique genetic counseling approach.

Congenital Abnormalities↗
PubMed1992

Autosomal dominant congenital laryngomalacia.

A family is presented in which congenital stridor due to laryngomalacia was evident in 9 individuals through 3 generations. This report confirms the autosomal dominant transmission of at least one type of laryngomalacia.

Adult↗
PubMed1992

Two-locus mitochondrial and nuclear gene models for mitochondrial disorders.

Stimulated by a large pedigree with a cochlear form of deafness, for which we considered a two-locus mitochondrial and nuclear gene model, we have extended the classic methods of segregation analysis to these classes of two-locus disorders. Based on the unique maternal transmission pattern of the mitochondria, we demonstrate that utilization of the maternal line pedigree allows us to simplify the various two-locus mitochondrial models to "one nuclear locus" models. Classifying the nuclear families into different independent groups by the mother's phenotypes allows us to estimate the nuclear gene frequency in one group and to use this estimate as the expected value to test the fitness of the model on the other group. In addition, if we restrict the analysis to specific subsets of the mating type(s), we can also test the model on specific groups of nuclear families without estimating the gene frequency. Goodness-of-fit tests can be performed on pooled sibship data as well as individual sibship data. These methods of analysis should assume increasing importance as more disorders with features of mitochondrial inheritance are identified.

Cell Nucleus↗
PubMed1992

Sensorineural deafness inherited as a tissue specific mitochondrial disorder.

We present here a large Israeli-Arab kindred with hereditary deafness. In this family 55 deaf subjects (29M, 26F), who are otherwise healthy, have been identified and traced back five generations to one common female ancestor. The deafness is progressive in nature, usually presenting in infancy and childhood. Audiometry on six deaf and seven unaffected subjects was consistent with severe to profound sensorineural hearing loss. Based on formal family segregation analysis, the inheritance of deafness in this family closely fits the expectation of a two locus model owing to the simultaneous mutation of a mitochondrial gene and an autosomal recessive gene. Thus, this disorder appears to have the unusual features of being an inherited tissue specific mitochondrial disease and apparently requiring the homozygous presence of a nuclear gene for clinical expression. Most importantly, this disorder presents a unique opportunity to investigate the molecular basis of hereditary non-syndromic deafness and normal hearing.

Adult↗
PubMed1992

The gene for familial Mediterranean fever in both Armenians and non-Ashkenazi Jews is linked to the alpha-globin complex on 16p: evidence for locus homogeneity.

Familial Mediterranean fever (FMF) is a recurrent inflammatory disorder characterized by short episodes of fever, peritonitis, pleuritis, and arthritis. While FMF has been shown to be inherited in an autosomal recessive fashion in both non-Ashkenazi Jews and Armenian families, clinical differences have raised the possibility of genetic heterogeneity. As its pathogenesis is unknown, mapping of the gene for FMF may provide the first objective method for early and accurate diagnosis of this disease. After excluding 45% of the entire human genome, we studied 14 Armenian and 9 non-Ashkenazi Jewish families with FMF and tested linkage with the alpha-globin locus on chromosome 16. Analysis of the PvuII length polymorphism of the 3' HVR (hypervariable region) probe showed significant linkage with the FMF gene (maximum lod score [lodmax] = 9.76 at maximum recombination fraction [theta] = .076). In the Armenians, the lodmax = 3.61 at theta = .10; and for the non-Ashkenazi Jews, lodmax = 6.28 at theta = .06. There was no evidence for genetic heterogeneity between the Armenians and the non-Ashkenazi Jews (chi 2 = 1.28; P = .26) or within either ethnic group (chi 2 = .00; P = .50). Thus, the gene for FMF is linked to the alpha-globin complex on chromosome 16p in both non-Ashkenazi Jews and Armenians.

Armenia↗
PubMed1991

Deletion of 20p 11.23----pter with normal growth hormone-releasing hormone genes.

Using a molecular analysis of the DNA from a patient with a deletion of chromosome 20 [46,XX,del(20)(p 11.23)], we have excluded the growth hormone-releasing hormone (GHRH) gene from the region 20p11.23----pter. The patient had minor facial anomalies. Rieger eye anomaly, a congenital heart defect, severe failure to thrive, and a neurosecretory problem in growth hormone (GH) secretion. Since the GHRH gene was previously mapped to chromosome 20, we used molecular genetic methods to determine whether the growth abnormalities were due to the deletion of this gene. DNAs of the patient and 2 normal control subjects were analyzed by quantitative Southern blotting using a DNA probe for the GHRH gene and 2 reference DNA probes mapping to chromosome 21. The GHRH gene was found to be present in 2 copies in the patient. This indicates that the gene for GHRH maps to the region outside the patient's deletion, in 20p11.23----qter. Furthermore, our results suggest that genes other than GHRH on 20p are important for developmental steps leading to normal neurosecretory function of GH and may also be involved in generating Rieger eye anomaly. Finally, GH deficiency and Rieger eye anomaly should be sought in other patients with deletions of 20p.

Child↗
PubMed1991

Perinatal lethal hypophosphatasia; clinical, radiologic and morphologic findings.

Clinical, radiographic and morphologic analysis of nineteen cases of perinatal (lethal) hypophosphatasia was performed. Three families each had two affected offspring. All of the patients had lethal short limb dwarfism with very soft calvaria. Other clinical findings included polyhydramnios, blue sclerae and spurs in the mid-portion of the forearms and lower legs. Considerable variability was found in the skeletal radiographs. In addition to the well known radiographic features such as generalized decrease in the size of ossified bones with some bones not ossified at all, other changes observed included: 1) marked variability in the amount of bone ossification; 2) variability between patients as to which bones were most severely affected; 3) unusually dense, round, flattened, butterfly shaped; and sagittally clefted vertebral bodies; 4) variability in femoral shape including "chromosome" like, "campomelic" like, and shortening with or without metaphyseal cupping or irregularities; 5) osteochondral projections (Bowdler spurs) of the midshaft of the fibula and ulna. Recognition of the marked clinical and radiographic variability in this autosomal recessive lethal skeletal dysplasia is important for accurate genetic counseling and prenatal diagnosis.

Bone and Bones↗
PubMed1990

Rearrangement of chromosome 15 in the region q11.2----q12 in an individual with obesity syndrome and her normal mother.

Rearrangement of the proximal long arm of chromosome 15 have been found in most patients with the Prader-Willi syndrome (PWS) and in some with Angelman syndrome. We present an individual with syndromic obesity and her normal mother, who both have an abnormal chromosome 15. The proposita is a 26-year-old women with marked obesity, acanthosis, nigricans, short fingers, and severe cone degeneration of the retina. She has high plasma insulin levels, hypothyroidism, and an empty sella on CT scan. High-resolution chromosome banding demonstrated an increase in band 15q12. Further analysis showed the same abnormal 15 in her normal mother but not in her normal sister. This case and recent reports in the literature indicate that duplication of chromosome 15q in the PWS region may be associated with a syndrome of obesity, acanthosis nigricans, empty sella, and rodcore dystrophy as well as with a normal phenotype. Whether normal individuals with such a duplication carry increased risk of having offspring with an obesity syndrome is yet to be determined.

Acanthosis Nigricans↗
PubMed1990

Megacystis-microcolon-intestinal hypoperistalsis syndrome in two male siblings.

Two male sibs with severe congenital megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) are presented. Both had enlarged bladder and hydronephrosis due to reduced bladder emptying, decreased bowel motility, and malrotation of the colon. Repeated careful ultrasound examination of the urinary tract in the second sib failed to show significant bladder enlargement prior to 25 weeks' gestation, which has been considered to be a reliable prenatal diagnostic sign for MMIHS. Slight bilateral enlargement of the renal pelves was noted at 21 weeks' gestation, and this may represent the earliest prenatally-detectable observation in this disease. Although more females than males with this condition have been reported, our cases provide support for an autosomal recessive mode of inheritance with a similar recurrence risk for both sexes.

Colon↗
PubMed1990

Serum amyloid A and P protein genes in familial Mediterranean fever.

Two recent studies have suggested the involvement of serum amyloid A (SAA) and P (APCS) genes in familial Mediterranean fever (MEF). To test the role of SAA and APCS in MEF and MEF-amyloidosis, we studied 17 informative families (15 Armenians, 2 non-Ashkenazi Jews) and 8 MEF patients with amyloidosis using a candidate gene approach. No evidence for any MEF-associated polymorphism was found in any of the 41 Armenian and Jewish MEF patients tested. Our family studies allowed us to rule out tight linkage between SAA and MEF (lod score = -2.16, theta less than or equal to 0.06). For APCS we found that the allele frequency in the MEF-amyloidosis patients was similar to that in 18 unrelated MEF patients without amyloidosis and their 33 healthy parents. Finally, we excluded close genetic linkage between APCS and MEF at 8.5 cM or less (lod score = -2.2).

Alleles↗
PubMed1990

Geleophysic dysplasia: a storage disorder affecting the skin, bone, liver, heart, and trachea.

Geleophysic dysplasia is characterized by typical facies ("happy natured"), small hands and feet, short stature, hepatomegaly, and progressive cardiac disease. We describe five patients (two of whom are siblings) with this disorder and document its variable expressivity. The facies were strikingly similar with small nose, anteverted nostrils, broad nasal bridge, and long thin upper lip with flat and long philtrum. Behavior, development, and intelligence were normal. Growth delay was noticed during infancy, and the two patients who completed normal puberty had marked short stature (140 and 150 cm), with relatively lean body habitus. The hands and feet were small, with short, plump tubular bones and broad proximal phalanges, associated with marked limitation in motion of fingers and wrists. The liver was enlarged after the age of 3 years. Two patients had mild mitral and tricuspid valve stenosis and one had severe aortic stenosis. The most severely affected child died at 3 1/2 years of age of airway obstruction as a result of progressive tracheal narrowing. Lysosomal storage vacuoles were found in skin epithelial cells from three patients whose skin was examined, and in the tracheal mucosa, liver, cartilage and macrophages of the child who died. The basic defect of this autosomal recessive lysosomal storage disease remains to be determined.

Adolescent↗
PubMed1990

Genetic marker family studies in familial Mediterranean fever (FMF) in Armenians.

Familial Mediterranean fever is an autosomal recessive disease manifested by recurrent short episodes of fever associated with polyserositis. It is common in a variety of Mediterranean and near Eastern populations. The biochemical defect is unknown, and there have been few studies of genetic marker associations or linkage with the disease. We have screened blood samples from members of 14 nuclear Armenian families, the population with the highest known gene frequency, for 19 different polymorphic phenotypic genetic markers. These 14 families included 31 affected and 43 unaffected family members. No association was found with any of the markers studied. Linkage could be excluded at the distance of 0-15% recombination with 14 markers. Linkage could not be excluded with 5 other markers. These results exclude the FMF gene from those portions of the human gene map that are at least 0.5% recombination distance from these 14 genetic markers, and represent the first comprehensive step in the eventual localization and isolation of the FMF gene.

Armenia↗