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J C Kaplan

Publications and source records attributed to J C Kaplan.

At least 19 recordsLinked to original sources
PubMed1998

Beta-sarcoglycan: genomic analysis and identification of a novel missense mutation in the LGMD2E Amish isolate.

The sarcoglycan complex is involved in the etiology of four autosomal recessive limb-girdle muscular dystrophies (LGMD2C-F). A missense mutation (T151R) in the beta-sarcoglycan gene on chromosome 4q12 has been shown to cause a mild form of LGMD2E in 11 families from a Southern Indiana Amish community sharing a common haplotype. We now report that two sibs from another Amish family with mild LGMD2E are compound heterozygotes for chromosome 4q12 markers. In order to characterize the genetic defect in this new family, we determined the genomic organization of the beta-sarcoglycan gene. A second missense mutation (R91C) has now been identified in this LGMD2E Amish family. This mutation is also present in the homozygous state in another family of probable Amish ancestry. Finally, analysis of all the components of the dystrophin-glycoprotein complex was performed for the first time on a biopsy from a patient homozygous for the beta-sarcoglycan mutation (T151R). Interestingly, in addition to the loss of the entire sarcoglycan complex, we detected a reduction of alpha-dystroglycan which suggests a role for the sarcoglycan complex in stabilizing alpha-dystroglycan at the sarcolemma.

Adolescent↗
PubMed1997

A biochemical, genetic, and clinical survey of autosomal recessive limb girdle muscular dystrophies in Turkey.

Autosomal recessive limb girdle muscular dystrophy (LGMD2) is a clinically and genetically heterogenous group of diseases involving at least six different loci. Five genes have already been identified: calpain-3 at LGMD2A (15q15), and four members of the sarcoglycan (SG) complex, alpha-SG at LGMD2D (17q21), beta-SG at LGMD2E (4q12), gamma-SG at LGMD2C (13q12), and delta-SG at LGMD2F (5q33-q34). The gene product at LGMD2B (2p13-p16) is still unknown and at least one other gene is still unmapped. We investigated 20 Turkish families (18 consanguineous) diagnosed as having LGMD2. Most of our patients had onset of symptoms before age 10. The phenotypes varied from severe to benign. We analyzed the SG complex by immunofluorescence and/or western blot. Genotyping was performed using markers defining the six known loci and the suspected genes were screened for mutations. Six of 17 index cases showed deficiency of the SG complex, by immunofluorescence and/or western blot. Seven cases involved one of the known genes of the SG complex (alpha, 2; beta, 1; and gamma, 4 cases), and five mutations were documented in the alpha- and gamma-SG genes. After linkage analysis, 10 families were characterized as having LGMD2A (calpain-3 deficiency), and all mutations were eventually identified. One family was classified as having LGMD2B and 1 family that has normal SGs was linked to the chromosome 5q33-q34 locus (LGMD2F). In 1 family there was no linkage to any of the known LGMD2 loci. It appears that in Turkey, there is a broad spectrum of genes and defects involved in LGMD2. It may be possible to correlate genotype to phenotype in LGMD2. All severe cases belonged to the gamma-SG-deficiency group. Nine calpain-3-deficient cases had intermediate and 1 had moderate clinical courses. The LGMD2B patient had a moderate clinical expression, whereas the LGMD2F case was truly benign.

Adolescent↗
PubMed1997

A point mutation in the glycerol kinase gene associated with a deletion in the dystrophin gene in a familial X-linked muscular dystrophy: non-contiguous gene syndrome involving Becker muscular dystrophy and glycerol kinase loci.

We report a family with an X-linked recessive muscular dystrophy characterised by exercise-induced myalgia, recurrent pigmenturia and mild proximal muscle involvement. Immunocytochemical and immunoblotting analysis in muscle, using the antibody directed against the rod domain of dystrophin, revealed a loss of immunoreactivity, but the immunolabelling using the antibodies directed against the COOH and NH2 domains of dystrophin were almost normal. The immunoreactions for alpha-sarcoglycan, gamma-sarcoglycan and beta-dystroglycan were normal. In the five male patients of this family with increased serum creatine kinase levels (from x8 to x50), mass spectrometry screening of the urine revealed a large increase in glycerol elimination which was quantified by enzymatic assay (from x14 to x39). An in-frame deletion of the dystrophin gene (exons 13-29) was found in the same five males and in three carrier females. All the deleted chromosomes also carried a missense mutation at nucleotide 947 of the Xp glycerol kinase (GK) gene resulting in a Thr to Met substitution at codon 278. These findings indicate that the two mutations cosegregate on the same chromosome in this family. This is the first reported case of two physically independent mutations, within the DMD and GK genes, which are contiguous but several hundred kilobases apart.

Adolescent↗
PubMed1997

Spectrum of CFTR mutations in Argentine cystic fibrosis patients.

The identification of different mutations which cause cystic fibrosis (CF) in Argentine patients has been performed. Initially, 10 of the most commonly mutated loci in 228 independent chromosomes were analyzed. Each allele was detected by PCR amplification of DNA samples either directly on polyacrylamide gels, by restriction enzyme digestion and agarose gels electrophoresis, or by hybridization with allele specific oligonucleotides. The delta F508 mutation was found in 57% of the alleles. The frequencies of the other CF mutations were as follows: G542X 3.9%, W1282X 3.1%, N1303K 1.7%, 1717 1-G-->A 0.9%, R553X 0.4%, R1162X 0.4%, whereas G551D, delta I507 and S549N were not found. This direct mutation analysis enabled the detection of 155/228 CF alleles (67%). Of the remaining 73 unidentified CF alleles, 22 were investigated for the 27 exons by DGGE and 9 rare mutations were identified. The incidence of the main CF mutations analyzed was similar to that of the South European population and markedly different from other Latin American countries. The mutation data presented here may be useful for designing DNA testing strategies for CF in Argentina.

Argentina↗
PubMed1997

Absence of alpha-sarcoglycan and novel missense mutations in the alpha-sarcoglycan gene in a young British girl with muscular dystrophy.

An 11-year-old white female presented with progressive proximal muscle weakness and marked calf hypertrophy. Muscle biopsy showed severe dystrophy with normal expression of dystrophin. There was complete absence of the 50kDa dystrophin-associated glycoprotein (alpha-sarcoglycan). DNA analysis showed novel point mutations (one missense and one splicing) in the alpha-sarcoglycan gene at chromosomal location 17q21, confirming the diagnosis of limb-girdle muscular dystrophy type 2D (LGMD-2D). We believe this is one of the first confirmed white cases of primary alpha-sarcoglycanopathy identified in the UK. This case supports the assumption of a wide geographic prevalence of severe childhood onset autosomal recessive muscular dystrophy and genetic heterogeneity. In the future, with improved diagnostic accuracy it is likely that more cases demonstrating primary or secondary deficiency of alpha-sarcoglycan will be identified. We would recommend staining for dystrophin-associated glycoproteins (sarcoglycans) in all new cases of muscular dystrophy with normal dystrophin, and confirmation with DNA analysis where possible.

Biopsy↗
PubMed1997

Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D).

Sarcoglycanopathies are a genetically heterogeneous group of autosomal recessive muscular dystrophies in which the primary defect may reside in any of the genes coding for the different partners of the sarcolemmal sarcoglycan (SG) complex: the alpha-SG (LGMD2D at 17q21.2), the beta-SG (LGMD2E at 4q12), the gamma-SG (LGMD2C at 13q12), and the delta-SG (LGMD2F at 5q33). We report a series of 20 new unrelated families with 14 different mutations in the alpha-SG gene. Along with the mutations that we previously reported this brings our cohort of patients with alpha-sarcoglycanopathy to a total of 31 unrelated patients, carrying 25 different mutations. The missense mutations reside in the extracellular domain of the protein. Five of 15 missense mutations, carried by unrelated subjects on different haplotype backgrounds and of widespread geographical origins, account for 58% of the mutated chromosomes, with a striking prevalence of the R77C substitution (32%). The severity of the disease varies strikingly and correlates at least in part with the amount of residual protein and the type of mutation. The recurrent R284C substitution is associated with a benign disease course.

Base Sequence↗
PubMed1997

Primary adhalinopathy (alpha-sarcoglycanopathy): clinical, pathologic, and genetic correlation in 20 patients with autosomal recessive muscular dystrophy.

Primary adhalin (or alpha-sarcoglycan) deficiency due to a defect of the adhalin gene localized on chromosome 17q21 causes an autosomal recessive myopathy. We evaluated 20 patients from 15 families (12 from Europe and three from North Africa) with a primary adhalin deficiency with two objectives: characterization of the clinical phenotype and analysis of the correlation with the level of adhalin expression and the type of gene mutation. Age at onset and severity of the myopathy were heterogeneous: six patients were wheel-chair bound before 15 years of age, whereas five other patients had mild disease with preserved ambulation in adulthood. The clinical pattern was similar in all the patients with symmetric characteristic involvement of trunk and limb muscles, calf hypertrophy, and absence of cardiac dysfunction. Immunofluorescence and immunoblot studies of muscle biopsy specimens showed a large variation in the expression of adhalin. The degree of adhalin deficiency was fairly correlated with the clinical severity. There were 15 different mutations (10 missense, five null). Double null mutations (three patients) were associated with severe myopathy, but in the other cases (null/missense and double missense) there was a large variation in the severity of the disease.

Adolescent↗
PubMed1997

Molecular diagnosis of congenital bilateral absence of the vas deferens: analyses of the CFTR gene in 64 French patients.

Congenital bilateral absence of the vas deferens is a congenital reproductive disorder that affects about one in 1000 male individuals. Screening of the entire coding and flanking sequences of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 64 males with CBAVD revealed that in only 23% CBAVD was caused by two CFTR mutations. The 5T allele in one copy, that causes reduced levels of the normal CFTR protein, in combination with a CFTR mutation in the other copy, was one of the most common causes of CBAVD. Twenty six per cent of men with CBAVD had the 5T allele. The presence of only one CFTR mutation or the 5T allele in 34% of patients suggests that undetected changes in CFTR may be involved in CBAVD. These molecular defects are probably mutations with partial penetrance. Moreover, the high proportion (20%) of patients with CBAVD who did not have CFTR mutations or the 5T allele allows to propose that another gene or genes could be responsible for CBAVD. In these cases, in vitro fertilization may be required and the genetic counselling appears to be very complex and additional studies, including CFTR mRNA and linkage analyses, are required to resolve these questions.

Cystic Fibrosis Transmembrane Conductance Regulato↗
PubMed1997

Prevalence, male germ-line origin and new patterns of inversions in haemophilia A.

Following the discovery of the FVIII gene inversion by Lakich et al. [1] and Naylor et al. [2], we have investigated this mutation in 108 French and Algerian severe haemophilia A patients. We have found that only 29 severe haemophiliacs (27%) exhibited the rearrangement whereas Lakich et al. [1] and Naylor et al. [2] respectively estimated the inversion frequency at 47% and 42% in severe haemophiliacs. The reason for this discrepancy is not accounted for. In this study, we observed two novel patterns of inversions as yet unreported. We did not find any correlation between the presence of the inversion and a particular RLFP haplotype, or ethnic origin, or the absence of a FVIII inhibitor. Among the cases with the inversion, the proportion of sporadic and transmitted cases was roughly equivalent and we also confirm that the inversion occurs preferentially in the male germ-line.

Algeria↗
PubMed1996

Absence of gamma-sarcoglycan (35 DAG) in autosomal recessive muscular dystrophy linked to chromosome 13q12.

We have partially sequenced rabbit skeletal muscle gamma-sarcoglycan, an integral component of the dystrophin-glycoprotein complex. Specific antibodies were produced against a gamma-sarcoglycan peptide and used to examine the expression of gamma-sarcoglycan in skeletal muscle of patients with severe childhood autosomal muscular dystrophy linked to chromosome 13q12 (SCARMD). We show by immunofluorescence and Western blotting that in skeletal muscle from these patients gamma-sarcoglycan is completely absent and alpha- and beta-sarcoglycan are greatly reduced in abundance, whereas other components of the DGC are preserved. In addition, we show that in normal muscle alpha-, beta-, and gamma-sarcoglycan constitute a tightly associated sarcolemma complex which cannot be disrupted by SDS treatment.

Animals↗
PubMed1996

Neurosensory hearing loss in secondary adhalinopathy.

We report mild-to-moderate neurosensory hearing loss and severe childhood autosomal recessive muscular dystrophy with adhalin-deficiency in two siblings from a Bulgarian sibship of Turkish origin. Microsatellite analysis excluded linkage to the adhalin gene, mutations of which cause limb girdle muscular dystrophy (LGMD) 2D, but was compatible with linkage to the gene locus of LGMD 2C on chromosome 13q12. Compound heterozygosity of the affected siblings was detected in this chromosomal region. A severe autosomal recessive form of neurosensory deafness has been linked to the same region (locus NSRD1) which is now contained in a 7 Mb YAC contig. Using polymorphic markers and STS PCR primers mapping in this contig, we did not find evidence for major rearrangements in the suspected region. These preliminary findings are not in favor of, but do not completely exclude a contiguous gene syndrome in these cases. Therefore, we consider a potential role of the putative 13q12 gene product and/or adhalin in neurosensory hearing.

Alleles↗
PubMed1996

A founder mutation in the gamma-sarcoglycan gene of gypsies possibly predating their migration out of India.

We investigated the molecular basis of a severe form of early onset autosomal recessive muscular dystrophy with sarcoglycan (SG) deficiency in seven large Gypsy families living in different parts of Western Europe and apparently not closely related. They were linked to the LGMD2C locus (13q12) suggesting a primary defect in the gamma-SG gene coding for the 35 kDa dystrophin-associated glycoprotein. All of the 18 investigated patients were homozygous for the same G-->A transition in codon 283 producing the replacement of a conserved cysteine of the extra-cellular domain of the protein by a tyrosine. All affected chromosomes in homozygous and heterozygous relatives carried the same allele 5 of the intragenic marker D13S232. Flanking markers were studied to delineate a common ancestral haplotype, the size of which was used to compute the date of the founding mutation. We found evidence that the mutation occurred between 60 and 200 generations ago, therefore possibly predating the commonly accepted date of migration of the Gypsy ancestors out of India.

Biomarkers↗
PubMed1996

Effects of zidovudine-selected human immunodeficiency virus type 1 reverse transcriptase amino acid substitutions on processive DNA synthesis and viral replication.

Certain amino acid substitutions in the reverse transcriptase (RT), including D67N, K70R, T215Y, and K219Q, cause high-level resistance of human immunodeficiency virus type 1 (HIV-1) to zidovudine (3'-azidothymidine; AZT) and appear to approximate the template strand of the enzyme-template-primer complex in structural models. We studied whether this set of mutations altered RT-template-primer interaction as well as their effect on virus replication in the absence of inhibitor. When in vitro polymerization was limited to a single association of an RT with an oligodeoxynucleotide-primed heteropolymeric RNA template (a single processive cycle), recombinant-expressed mutant 67/70/215/219 RT synthesized 5- to 10-fold more high-molecular-weight DNA products (>200 nucleotides in length) than wild-type RT. This advantage was maintained as deoxynucleoside triphosphate (dNTP) concentrations were decreased to limiting levels. In contrast, no difference was seen between wild-type and mutant RTs under conditions allowing repeated associations of enzyme with template-primer. Because intracellular dNTP concentrations are low prior to mitogenic stimulation, we compared replication of mutant 67/70/215/219 virus and wild-type virus in peripheral blood mononuclear cells (PBMC) stimulated before and after infection. In the absence of inhibitor, mutant 67/70/215/219 virus had a replication advantage in PBMC stimulated with phytohemagglutinin and interleukin-2 after infection, but virus replication was similar in PBMC stimulated before infection in vitro. The results confirm that RT mutations D67N, K70R, T215Y, and K219Q affect an enzyme-template-primer interaction in vitro and suggest that such substitutions may affect HIV-1 pathogenesis during therapy by increasing viral replication capacity in cells stimulated after infection.

Base Sequence↗