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Biomedical subjects

R Carmi

Publications and source records attributed to R Carmi.

At least 37 records · Page 2Linked to original sources
PubMed1998

A nonsense mutation (R242X) in the branched-chain alpha-keto acid dehydrogenase E1alpha subunit gene (BCKDHA) as a cause of maple syrup urine disease. Mutations in brief no. 160. Online.

Mutation analysis of DNA from cultured amniocytes with absent branched-chain alpha-ketoacid dehydrogenase activity revealed a C to T transition producing a nonsense mutation (R242X) in exon 7 of the gene encoding the E1a subunit of this multienzme complex (BCKDHA). This pregnancy occured in a large consanguinous pedigree with mutiple individuals with maple syrup urine disease (MSUD). PCR amplification of the region surrounding exon 7 allowed the identification of this mutation as well as two other previously identified mutations which cause MSUD.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1998

Prevalence of glucocerebrosidase mutations in the Israeli Ashkenazi Jewish population.

Gaucher disease is the most prevalent inherited disease among Ashkenazi Jews. It is very heterogeneous due to a large number of mutations within the glucocerebrosidase gene, whose impaired activity is the cause for this disease. Aiming at determining Gaucher carrier frequency among the Ashkenazi Jewish population in Israel, 1,208 individuals were molecularly diagnosed for six mutations known to occur among Ashkenazi Jewish Gaucher patients, using the newly developed Pronto Gaucher kit. The following mutations were tested: N370S, 84GG, IVS2+1, D409H, L444P, and V394L. Molecular testing of these mutations also allows identification of the recTL allele. The results indicated that Gaucher carrier frequency is 1:17 within the tested population. The prevalence of N370S carriers is 1:17.5. This implies that approximately 1:1225 Ashkenazi Jews will be homozygous for the N370S mutation. Actually, in our study of 1,208 individuals one was found to be homozygous for the N370S mutation. The actual number of known Ashkenazi Jewish Gaucher patients with this genotype is much lower than that expected according to the frequency of the N370S mutation, suggesting a low penetrance of this mutation. Results of loading experiments in cells homozygous for the N370S mutation, as well as cells homozygous for the L444P and the D409H mutations, exemplified this phenomenon.

Cells, Cultured↗
PubMed1998

Hypocomplementemic autosomal recessive hemolytic uremic syndrome with decreased factor H.

We describe the clinical course, complement components, and pathological findings of 10 infants with autosomal recessive hemolytic uremic syndrome (HUS). All patients were members of one extended highly inbred Bedouin kindred. The median age of presentation was 2 weeks (range 1-20 weeks). Eight patients died, 2 patients are alive, on dialysis. Renal biopsies revealed thrombotic microangiopathy with a predominant early arteriolar involvement and subsequent development of ischemic glomerular changes. Immunofluorescence was positive for C3 in glomeruli. All patients had low complement components levels during and between relapses, and in some this was evident soon after birth and prior to the onset of symptoms. This deficiency could not be normalized by repeated plasma transfusions. Biosynthetic labelling of patients' fibroblasts demonstrated normal rates of C3 protein synthesis. Serum factor H levels were greatly decreased or absent in 4 patients tested and moderately decreased in 15 of 23 healthy unaffected siblings and patients. This defect may cause complement activation and consumption, possibly at the endothelial cell level.

Arabs↗
PubMed1998

Use of isolated inbred human populations for identification of disease genes.

The genetic mapping of disease loci involves the use of patient phenotype and genotype data in the search for genetic markers that segregate, or are associated with, a trait or disorder. Genetically isolated populations offer many advantages for such studies. The high degree of inbreeding and/or founder effects in some small population isolates result in an increased incidence of recessive disorders. Monogenic disorders are less likely to show non-allelic heterogeneity in isolated populations than in more diverse populations. The use of isolated populations also reduces the complexity of polygenic disorders by reducing the number of loci probably involved in the disorder. Finally, a variety of strategies can be used with particular efficacy for the mapping of disease genes in isolated populations.

Consanguinity↗
PubMed1998

Decisions regarding pregnancy termination among Bedouin couples referred to third level ultrasound clinic.

OBJECTIVE: To identify predictors of parental decision whether to terminate a pregnancy after a diagnosis of a major congenital malformation in a traditional society. STUDY DESIGN: The Bedouin Arabs in southern Israel are a traditional society, with a high incidence of congenital disorders. Data were abstracted from medical records of 295 families who sought counseling in the third level ultrasound clinic between 1990 and 1996. Statistical analysis included univariate and multiple logistic regression. RESULTS: The diagnosis of a major malformation was confirmed in 64% of the cases. Pregnancy termination was a realistic option for 125 women (66.5%) as the rest were too advanced in their pregnancy. Such a delay was less common in cases of multiple malformations than in a single malformation (19.2% versus 39.0% respectively, P < 0.01). Forty-nine of the 125 women (39.2%) chose to terminate their pregnancy. The only significant predictors of termination decision were earlier gestational week at diagnosis and previous uncompleted pregnancies. CONCLUSIONS: These findings indicate the importance of promoting early genetic counseling and early prenatal diagnosis, for any population where abortions are not readily acceptable.

Abortion, Induced↗
PubMed1998

Reticulolinear aplasia cutis congenita of the face and neck: a distinctive cutaneous manifestation in several syndromes linked to Xp22.

A distinct form of aplasia cutis congenita presenting as linear facial skin defects has been described under a variety of names as Xp deletion syndrome. MIDAS (microphthalmia, dermal aplasia and sclerocornea) syndrome, MLS (microphthalmia and linear skin defects) and Gazali-Temple syndrome. The syndrome is lethal in males, and its severity in females varies from a relatively mild residual facial scarring with short stature to lethal developmental organ malformations. A new case with peculiar ultrastructural findings is presented. A review of the literature suggests that these associations represent a series of contiguous-gene syndromes.

Chromosome Deletion↗
PubMed1998

The relationship between congenital cardiovascular malformations and spontaneous abortion in preceding pregnancy.

Previous studies have shown an increased frequency of spontaneous abortions in the pregnancy preceding a fetus or a newborn with neural tube defect (NTD) compared with a normal newborn. One explanation of this observation is the trophoblastic cell rest hypothesis put forward by Knox and Clarke, suggesting a teratogenic interaction between the developing embryo and pathological remnants of a previous pregnancy. The other explanation is that the previously lost fetus was also affected with neural tube defect. The aim of this study was to verify whether this observation is also valid for congenital cardiovascular malformations (CCVM). Demographic and obstetric data of 99 mothers (58 Jewish and 41 Bedouin) of newborns who died in the neonatal period from isolated CCVM were compared with those of 103 mothers (48 Jewish and 55 Bedouin) of newborns who died of congenital defects other than NTD and CCVM. Spontaneous abortions in the preceding pregnancy were found in 32% of the cases with CCVM compared with 14% of cases with other defects (ODs) (P=0.0012; odds ratio=3.1, 95% confidence interval 1.5-6.4). This significant difference was independent of maternal age and number of pregnancies or deliveries. No difference was found between Jews and Bedouins. As there is no indication in the literature that fetuses with isolated CCVM tend to be spontaneously aborted, our findings are more supportive of the trophoblastic cell rest theory.

Abortion, Spontaneous↗
PubMed1998

Linkage of infantile Bartter syndrome with sensorineural deafness to chromosome 1p.

Bartter syndrome (BS) is a family of disorders manifested by hypokalemic hypochloremic metabolic alkalosis with normotensive hyperreninemic hyperaldosteronism. We evaluated a unique, inbred Bedouin kindred in which sensorineural deafness (SND) cosegregates with an infantile variant of the BS phenotype. Using a DNA-pooling strategy, we screened the human genome and successfully demonstrated linkage of this unique syndrome to chromosome 1p31. The genes for two kidney-specific chloride channels and a sodium/hydrogen antiporter, located near this region, were excluded as candidate genes. Although the search for the disease-causing gene in this family continues, this linkage further demonstrates the genetic heterogeneity of BS. In addition, the cosegregation of these phenotypes allows us to postulate that a single genetic alteration may be responsible for the SND and the BS phenotype. The identification and characterization of this gene would lead to a better understanding of the normal physiology of the kidney and the inner ear.

Bartter Syndrome↗
PubMed1998

Homozygosity and linkage-disequilibrium mapping of the syndrome of congenital hypoparathyroidism, growth and mental retardation, and dysmorphism to a 1-cM interval on chromosome 1q42-43.

The syndrome of hypoparathyroidism associated with growth retardation, developmental delay, and dysmorphism (HRD) is a newly described, autosomal recessive, congenital disorder with severe, often fatal consequences. Since the syndrome is very rare, with all parents of affected individuals being consanguineous, it is presumed to be caused by homozygous inheritance of a single recessive mutation from a common ancestor. To localize the HRD gene, we performed a genomewide screen using DNA pooling and homozygosity mapping for apparently unlinked kindreds. Analysis of a panel of 359 highly polymorphic markers revealed linkage to D1S235. The maximum LOD score obtained was 4.11 at a recombination fraction of 0. Analysis of three additional markers-GGAA6F06, D1S2678, and D1S179-in a 2-cM interval around D1S235 resulted in LOD scores >3. Analysis of additional chromosome 1 markers revealed evidence of genetic linkage disequilibrium and place the HRD locus within an approximately 1-cM interval defined by D1S1540 and D1S2678 on chromosome 1q42-43.

Chromosome Mapping↗
PubMed1998

A Bedouin kindred with infantile nephronophthisis demonstrates linkage to chromosome 9 by homozygosity mapping.

A novel type of infantile nephronophthisis was identified in an extended Bedouin family from Israel. This disease has an autosomal recessive mode of inheritance, with the phenotypic presentation ranging from a Potter-like syndrome to hyperechogenic kidneys, renal insufficiency, hypertension, and hyperkalemia. Affected individuals show rapid deterioration of kidney function, leading to end-stage renal failure within 3 years. Histopathologic examination of renal tissue revealed variable findings, ranging from infantile polycystic kidneys to chronic tubulointerstitial nephritis, fibrosis, and cortical microcysts. A known familial juvenile nephronophthisis locus on chromosome 2q13 and autosomal recessive polycystic kidney disease on chromosome 6p21.1-p12 were excluded by genetic linkage analysis. A genomewide screen for linkage was conducted by searching for a locus inherited by descent in all affected individuals. Pooled DNA samples from parents and unaffected siblings and individual DNA samples from four affected individuals were used as PCR templates with trinucleotide- and tetranucleotide-repeat polymorphic markers. Using this approach, we identified linkage to infantile nephronophthisis for markers on chromosome 9q22-31. The disorder maps to a 12.9-cM region flanked by markers D9S280 and GGAT3G09.

Arabs↗
PubMed1998

Human autosomal recessive osteopetrosis maps to 11q13, a position predicted by comparative mapping of the murine osteosclerosis (oc) mutation.

Autosomal recessive osteopetrosis is a rare congenital disorder characterized by the development of abnormally dense bones, acrocephaly, severe anemia, hepatosplenomegaly and progressive deafness and blindness. The clinical course is rapidly progressive and is lethal at a very young age in the absence of a bone marrow transplant. The failure to remodel developing bone that is the basis of the disease process is most likely due to a dysfunction of the bone resorptive cell, the osteoclast. This phenotype is similar to that of the murine mutation osteosclerosis (oc), which is localized to proximal mouse chromosome 19. Given the similarity between the human and murine phenotypes, we tested whether human osteopetrosis maps to a region of conserved synteny. Microsatellite markers in the region of 11q12-13 were found to be linked to osteopetrosis in two consanguineous Bedouin kindreds. Recombination events were used to define the disease interval to an approximately 14 cM region between D11S1983 and D11S2371. A maximum LOD score of 7. 94 was obtained with D11S449 at straight theta = 0.

Animals↗
PubMed1998

Clinical presentation and outcome in primary familial hypomagnesaemia.

The clinical presentation and long term outcome (mean follow up eight years, range 0.25 to 21) of 15 patients with autosomal recessive primary familial hypomagnesaemia is described. The most common (67%) presenting events were generalised hypocalcaemic-hypomagnesaemic seizures at a mean (SD) age of 4.9 (2.5) weeks. Thirteen infants, treated soon after diagnosis with high dose enteral magnesium developed normally. Their serum calcium returned to normal concentrations but serum magnesium could not be maintained at normal concentrations (0.53 (0.12 SD) mmol/l; normal > 0.62). Delay in establishing a diagnosis led to a convulsive disorder with permanent neurological impairment in two infants. Reported complications of prolonged hypomagnesaemia such as renal stones, hypertension, arrhythmias, sudden death, or dyslipidaemia were not observed.

Consanguinity↗
PubMed1997

Niemann-Pick C1 disease gene: homology to mediators of cholesterol homeostasis.

Niemann-Pick type C (NP-C) disease, a fatal neurovisceral disorder, is characterized by lysosomal accumulation of low density lipoprotein (LDL)-derived cholesterol. By positional cloning methods, a gene (NPC1) with insertion, deletion, and missense mutations has been identified in NP-C patients. Transfection of NP-C fibroblasts with wild-type NPC1 cDNA resulted in correction of their excessive lysosomal storage of LDL cholesterol, thereby defining the critical role of NPC1 in regulation of intracellular cholesterol trafficking. The 1278-amino acid NPC1 protein has sequence similarity to the morphogen receptor PATCHED and the putative sterol-sensing regions of SREBP cleavage-activating protein (SCAP) and 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase.

Amino Acid Sequence↗
PubMed1997

Familial hypomagnesemia maps to chromosome 9q, not to the X chromosome: genetic linkage mapping and analysis of a balanced translocation breakpoint.

Familial hypomagnesemia with secondary hypocalcemia (HSH) (MIM 307600) was studied in three inbred Bedouin kindreds from Israel. The three kindreds, one extended and two nuclear families, contained 13 affected individuals, 11 males and two females. Assuming that the individuals affected with hypomagnesemia shared a chromosomal region inherited from a common ancestor, we used a DNA pooling strategy in a genome-wide search for loci which show homozygosity for shared alleles in affected individuals. DNA samples from affected individuals within a single kindred were pooled and used as the template for PCR amplification of short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected siblings and parents were used as controls. A shift towards homozygosity was observed in the affected DNA pool compared with the control pools with D9S301 (GATA7D12). Genotyping of individual DNA samples with D9S301 and several flanking markers confirmed linkage to chromosome 9 with maximum LOD scores of 3.4 (theta = 0.05), 3.7 (theta = 0) and 2.3 (theta = 0) for the three families. We have identified a 14 cM interval on chromosome 9 (9q12-9q22.2), flanked by proximal marker D9S1874 and distal marker D9S1807, within which all affected individuals from the three kindreds are homozygous for a shared haplotype. The disease segregates with a common affected haplotype in the three families, suggesting that hypomagnesemia is caused by a common ancestral mutation in these families. Although HSH has been previously reported to be X linked, these linkage data demonstrate that the disorder is an autosomal recessive disease in these kindreds. Mapping of a chromosomal breakpoint in a somatic cell line established from a patient with HSH and a balanced X;9 translocation placed the chromosomal breakpoint in a 500 kb region flanked by D9S1844 and D9S273. Identification of the gene responsible for hypomagnesemia will provide insight into the regulation of this essential cation.

Arabs↗
PubMed1997

Construction of P1-derived artificial chromosome and yeast artificial chromosome contigs encompassing the DFNB7 and DFNB11 region of chromosome 9q13-21.

DFNB7 and DFNB11, two loci for autosomal recessive nonsyndromic hearing loss (ARNSHL), have been mapped to chromosome 9q13-21 in separate consanguineous families. Using a radiation hybrid map, we have determined the correct marker order in the DFNB7/11 region and have demonstrated that the DFNB11 locus resides within a redefined DFNB7 interval. The gene(s) responsible for ARNSHL at these loci resides within an approximately 1 cM interval bounded by markers D9S1806 (centromeric) and D9S769 (telomeric). A recently discovered Indian family confirms the new telomeric boundary. To assist in the identification and cloning of candidate genes, YAC and PAC contigs were constructed. A total of 19 YAC and 23 PAC clones were utilized to span the affected region and ensure double coverage throughout. Twenty-two previously published STSs and 21 new STSs were used to determine marker order and confirm the integrity of the contig. Using a positional cloning strategy we have identified three cochlear expressed genes that map to the DFNB7/11 interval.

Chromosome Mapping↗
PubMed1996

Prenatal diagnosis of glycogen storage disease type 1a by single stranded conformation polymorphism (SSCP).

Glycogen storage disease type 1a (GSD 1a), a severe metabolic disorder, is caused by the absence of glucose-6-phosphatase (G6Pase) activity. Diagnosis is currently established by demonstrating the lack of G6Pase activity in the patient's liver specimen. Enzymatic diagnosis cannot be performed in chorionic villi or amniocytes as G6Pase is active only in the liver, kidney, and intestinal mucosa. Recent cloning of the G6Pase gene and subsequent identification of the mutations causing GSD 1a have led to the possibility of performing DNA-based diagnosis in chorionic villus samples (CVS) or amniocytes. Here we report the first DNA-based prenatal diagnosis in two families in whom GSD 1a patients were diagnosed. In one Jewish family with a previously identified R83C mutation, single-stranded conformation polymorphism (SSCP) analysis of the DNA extracted from CVS showed a homozygous R83C mutant pattern. As a result, the pregnancy was terminated and the diagnosis was confirmed on DNA analysis of the aborted fetus. In another family of Arabic extraction in which a V166G mutation has been identified in one of the siblings, SSCP analysis performed on DNA extracted from CVS presented the pattern of a normal control. The pregnancy was carried to term and a healthy baby was born. Thus, once mutations causing the disease are identified, prenatal diagnosis of GSD 1a is possible. SSCP analysis of DNA prepared from CVS is reliable, simple and fast, making it a suitable method for prenatal diagnosis.

Chorionic Villi Sampling↗