Molecular heterogeneity of myophosphorylase deficiency (McArdle's disease): a genotype-phenotype correlation study.

We report on 54 Spanish patients with McArdle's disease from 40 unrelated families. Molecular analysis revealed that the most common R49X mutation was present in 70% of patients and 55% of alleles. The G204S mutation was less frequent and found in 14.8% of patients and 9% of mutant alleles. The W797R mutation was observed in 16.5% of patients, accounting for 13.7% of mutant alleles. Moreover, 78% of mutant alleles among Spanish patients can be identified by using polymerase chain reaction-restriction fragment length polymorphism analysis for the R49X, G204S, and W797R mutations, which makes noninvasive diagnosis possible through molecular genetic analysis of blood DNA. Six novel mutations were found. Three were missense mutations, E348K, R601W, and A703V; two nonsense mutations, E124X and Q754X; and one single base pair deletion, 533 delA. No clear genotype-phenotype correlation emerges from our study. Most of the mutations of uncharged and solvent inaccessible residues and the truncations must disrupt the basic structure of the protein. The mutations of charged residues would be expected to interfere with internal hydrogen bonding networks, introducing severe incompatible partnering that is caused by poor packing or electrostatic repulsions.

Lipomatosis simétrica múltiple: Aportaciónde un caso y revisión de la literatura / Multiple symmetrical lipomatosis. report of a case and review of the literature

La lipomatosis simétrica múltiple es una enfermedad que se caracteriza por presentar múltiples y simétricas masas de tejido adiposo no encapsulado, indoloras y localizadas frecuentemente en cuello, hombros y otras partes del tronco. Habitualmente se asocia a alcoholismo y trastornos metabólicos, y puede cursar con afectación mediastínica y neuropatía. Presentamos el caso de un paciente de 63 años de edad, con importante hábito enólico. Se describen las características clínico-morfológicas, los hallazgos histopatológicos de una biopsia de grasa subcutánea y músculo esquelético, además de otras pruebas complementarias y los posibles tratamientos electivos. Se incluye, además, una amplia revisión de la literatura sobre esta patología (AU)

Autosomal dominant limb-girdle muscular dystrophy: a large kindred with evidence for anticipation.

BACKGROUND: Fourteen genetically distinct forms of limb-girdle muscular dystrophy (LGMD) have been identified, including five types of autosomal dominant LGMD (AD-LGMD). OBJECTIVE: To describe clinical, histologic, and genetic features of a large Spanish kindred with LGMD and apparent autosomal dominant inheritance spanning five generations. METHOD: The authors examined 61 members of the family; muscle biopsies were performed on five patients. Linkage analysis assessed chromosomal loci associated with other forms of AD-LGMD. RESULTS: A total of 32 individuals had weakness of the pelvic and shoulder girdles. Severity appeared to worsen in successive generations. Muscle biopsy findings were nonspecific and compatible with MD. Linkage analysis to chromosomes 5q31, 1q11-q21, 3p25, 6q23, and 7q demonstrated that this disease is not allelic to LGMD forms 1A, 1B, 1C, 1D, and 1E. CONCLUSIONS: This family has a genetically distinct form of AD-LGMD. The authors are currently performing a genome-wide scan to identify the disease locus.

Evaluation of heart involvement in gamma-sarcoglycanopathy (LGMD2C). A study of ten patients.

Thorough non-invasive cardiovascular studies were conducted in a series of ten gamma-sarcoglycanopathy Gypsy patients with the founder C283Y mutation in 13q12. Results were compared with those obtained in an age-matched group of normal boys and girls. The studies included electrocardiographic and echocardiographic evaluations using pulsed wave Doppler tissue imaging to assess regional diastolic function and myocardial velocities at various levels. This study confirms the significant electrocardiographic abnormalities described in previous studies. Furthermore, measurement of myocardial velocity at different levels demonstrated an abnormal relaxation pattern in the tricuspid annulus in four of the oldest patients, which strongly suggests intrinsic myocardial involvement of the right ventricle. To our knowledge, these specific studies have not been previously performed in a clinically and genetically homogeneous group of gamma-sarcoglycanopathy patients and suggest primary myocardial involvement probably due to gamma-sarcoglycan deficiency in cardiac muscle fibres. Our results could be of interest in the follow-up of these patients and the prevention and treatment of late cardiological complications.

[Gamma-sarcoglycanopathy: clinico-pathological and genetic study of 11 cases]. / Gamma-sarcoglicanopatía: estudio clinicopatológico y genético de 11 casos.

INTRODUCTION: Limb Girdle Muscular Dystrophy type 2C (LGMD2C) is an autosomal recessive dystrophy due to the deficit of gamma-sarcoglycan, one of the proteins of the dystrophin-associated proteins complex (DAP). A new mutation in the gamma-sarcoglycan gene, 13q12, has been described recently and is exclusive of the gypsy community. OBJECTIVE: To describe the clinicopathological and the genetic findings of eleven cases from a Spanish gypsy family with LGMD2C and the mutation C283Y. MATERIAL AND METHODS: We describe a large gypsy family with the C283Y mutation and eleven affected patients. We have performed an extensive clinical and pathological study with immunohistochemistry and Western blot analyses in the eleven patients and a genetic study of a total of twenty-seven members of the family. RESULTS: The patients presented a severe muscular dystrophy with a dystrophic pattern in the muscle biopsy, normal immunolabeling for dystrophin, very weak for alpha-, beta- and delta-sarcoglycan and absent for gamma-sarcoglycan. These eleven patients were found to be homozygous for the mutation and twelve other members of the family, heterozygous. CONCLUSIONS: The clinical picture and the evolution of the disease herein described is similar to that observed in DMD. Two fundamental differences were found: the autosomal recessive mode of inheritance, and the normal immunohistochemistry and immunoblot for dystrophin in the skeletal muscle.

[Dystrophinopathies, congenital muscular dystrophy, limb-girdle dystrophies: updated classification]. / Distrofinopatías, distrofia muscular congénita y distrofias de cinturas: clasificación actualizada.

OBJECTIVES: To review the up-dated classification of limb girdle muscular dystrophies (LGMDs) in relation to the defective protein and the genetic abnormality. To explain how these proteins are related to dystrophin and to the proteins of the extracellular matrix. To show that an accurate diagnosis is necessary and that it can be adequately made in neuromuscular pathology laboratories. DEVELOPMENT: We present a study of the different types of LGMDs, dystrophinopathies and congenital muscular dystrophy. We emphasize the recent events which concluded in the identification of these disorders, the genetic alteration, the defective proteins and, briefly, the clinical features. CONCLUSIONS: The recent identification of numerous skeletal muscle proteins and of the codifying genes made possible a new classification of a large group of muscular dystrophies. The possibility to study these proteins on the muscle biopsy with immunohistochemistry and Western blot techniques indicates the need of an accurate diagnosis in specialized neuromuscular laboratories. Since there is a great number of genes discovered and of mutations within the same gene, and the clinical picture of different diseases can be similar, a previous study of the protein is advisable as a guide for a further genetic study.