Recessive Limb-girdle Muscular Dystrophy Research Articles

Confirmation of the 2p locus for the mild autosomal recessive limb-girdle muscular dystrophy gene (LGMD2B) in three families allows refinement of the candidate region.

The mild autosomal recessive limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of muscle diseases. The first gene to be mapped and associated with this phenotype was a locus on 15q based on linkage analysis in families from a French geographic isolate. These results have been confirmed in other populations, but it was shown that there is genetic heterogeneity for this form of LGMD. Recently, a second locus has been mapped to chromosome 2p. The confirmation of the mapping of this second locus in LGMD families from different populations is of utmost importance for the positional cloning of this gene (HGMW-approved symbol LGMD2B). In this publication, haplotypes generated from five chromosome 2 markers from all of the known large families linked to chromosome 2p are reported together with the recombinants that show the current most likely location of the LGMD 2B gene.

Genetic heterogeneity of autosomal recessive limb-girdle muscular dystrophy in a genetic isolate (Amish) and evidence for a new locus.

Limb-girdle muscular dystrophy (LGMD) is a hereditary myopathy presenting clinical and genetic heterogeneity. In 1991, a recessive form (LGMD2A) was linked to chromosome 15q in a genetic isolate from the Isle of La Réunion. Confirmation of this localization was subsequently reported in Brazilian and northern Indiana Amish pedigrees. Here we report the exclusion of the LGMD2A locus in six Amish kindreds from southern Indiana that are related by multiple consanguineous links to the same northern Indiana families in which the involvement of the chromosome 15 locus was previously demonstrated. These findings indicate unexpected genetic heterogeneity of LGMD in an Indiana Amish isolate. Furthermore, genetic analyses also ruled out the possible involvement of the chromosome 2 locus recently described (LGMD2B), thus demonstrating that a mutation within at least one additional locus leads to this condition. Several candidate genes putatively involved in neuromuscular disorders were also excluded.

A gene for autosomal recessive limb-girdle muscular dystrophy maps to chromosome 2p.

The limb-girdle muscular dystrophies are a clinically and genetically heterogeneous group of disorders. We have studied two large inbred families of different ethnic origin and excluded linkage to LGMD2 on chromosome 15q and SCARMD on chromosome 13. Proceeding to a genomic linkage search, we have now identified linkage to markers D2S134 and D2S136 on chromosome 2p (maximum lod score 3.57 at zero recombination). The phenotype in the two families was similar, with onset in the pelvic girdle musculature in the late teens and usually relatively slow progression. This work identifies a second locus for autosomal recessive limb-girdle muscular dystrophy.

Evidence of genetic heterogeneity in the autosomal recessive adult forms of limb-girdle muscular dystrophy following linkage analysis with 15q probes in Brazilian families.

The autosomal recessive limb-girdle muscular dystrophies (LGMD) represent a heterogeneous group of diseases which may be characterised by one or more autosomal loci. A gene at 15q has recently been found to be responsible for a mild form of LGMD in a group of families from the isolated island of Réunion, now classified as LGMD2. Based on results of eight out of 11 large Brazilian LGMD families of different racial background (which were informative for the closest available probe to the LGMD2 gene), we confirmed linkage to the LGMD2 gene at 15q in two of these families and exclusion in six others. These data provide the first evidence of genetic heterogeneity for the autosomal recessive limb-girdle muscular dystrophies.

Limb-girdle syndrome: a genetic study of 22 large Brazilian families comparison with X-linked Duchenne and Becker dystrophies

The differential clinical diagnosis between the X-linked muscular dystrophies (DMD and BMD) and autosomal recessive limb-girdle muscular dystrophy (LGMD), which is extremely important for genetic counseling, may be very difficult. The aim of the present report is to describe clinical and laboratory findings in patients from large families, with AR inheritance, in an attempt to characterize better cases which have been diagnosed as LGMD compared with the X-linked forms. The main features analysed are: age of onset and of confinement to a wheelcchair, reproductive performance, serum enzymes (CK and PK) and dystrophin assessment (through immunohistochemistry and Western blot). Twenty-two families, with 62 affected patients diagnosed as limb-girdle muscular dystrophy, were included in this report. In 19 families, the patients had a milder clinical course, while in the remaining 3, the progression of the disease was continuous and clinically similar to X-linked DMD (“DMD-like”). A high consanguinity rate was observed among the parents of the affected patients (77%). No major clinical difference was observed between the X-linked and the AR forms. However, muscle dystrophin was found qualitatively and quantitatively normal in the autosomal forms but absent or abnormal in the X-linked ones. The reproductive performance was significantly higher for male than female patients. In addition, a surprising finding was the significantly greater fitness estimated for male LGMD cases as compared with Becker patients of comparable age studied in our center. The implications of such findings are discussed.

Benign muscular dystrophy: risk calculation in families with consanguinity.

This report concerns two families in which the index patients are sporadic cases of a benign form of muscular dystrophy. In both families the sisters of the patients have married a close relative. The respective risks for a child of these consanguineous marriages being affected with either X linked Becker muscular dystrophy or autosomal recessive limb girdle muscular dystrophy is calculated using pedigree information, results of serum creatine kinase determinations, and also, in one family, results of DNA typing using RFLPs from the short arm of the X chromosome.