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Biomedical subjects

M de Marchi

Publications and source records attributed to M de Marchi.

7 recordsLinked to original sources
PubMed1999

LINE-1 elements at the sites of molecular rearrangements in Alport syndrome-diffuse leiomyomatosis.

Deletions encompassing the 5' termini of the paired type IV collagen genes COL4A5 and COL4A6 on chromosome Xq22 give rise to Alport syndrome (AS) and associated diffuse leiomyomatosis (DL), a syndrome of disseminated smooth-muscle tumors involving the esophagus, large airways, and female reproductive tract. In this study, we report isolation and characterization of two deletion junctions. The first, in a patient described elsewhere, arose by a nonhomologous recombination event fusing a LINE-1 (L1) repetitive element in intron 1 of COL4A5 to intron 2 of COL4A6, resulting in a 13.4-kb deletion. The second, in a previously undescribed family, arose by unequal homologous recombination between the same L1 and a colinear L1 element in intron 2 of COL4A6, resulting in a>40-kb deletion. L1 elements have contributed to the emergence of this locus as a site of frequent recombinations by diverse mechanisms. These give rise to AS-DL by disruption of type IV collagen and perhaps other as yet unidentified genes, evidenced by deletions as small as 13.4 kb.

Adult↗
PubMed1989

Pulsed-field gel analysis of human immunoglobulin heavy-chain constant region gene deletions reveals the extent of unmapped regions within the locus.

The human immunoglobulin heavy-chain constant region gene locus is organized in three main gene groups, the physical distances of which are unknown. Different types of gene deletions, originated by unequal crossingover, have been found to encompass one or more genes in the locus. We have analyzed some of these deletions by means of pulsed-field gel electrophoresis, which allows resolution of large DNA fragments. By identifying a fragment containing two of the main gene groups and by observing the size reduction of this fragment in subjects with deletions, we were able to estimate the distance between the two groups and better locate the pseudogene in-between.

Chromosome Deletion↗
PubMed1989

Gene deletions within the human immunoglobulin heavy chain constant region gene cluster.

Gene deletions due to unequal crossing-over events represent a not uncommon cause of immunoglobulin isotype deficiency. A variety of deleted haplotypes has been ascertained in the Italian population by means of screening for different Ig isotypes followed by Southern blot analysis of the deficient probands. The total frequency of gene deletions involving the gamma 2 and/or gamma 4 genes amounts to about 1/60; among these, a higher frequency was observed for multigene compared with single gene deletions. Carriers of multiple deficiencies due to gene deletions are able to activate compensation mechanisms, avoiding the usual pathological consequences of the deficiency.

Chromosome Deletion↗
PubMed1985

Familial progressive external ophthalmoplegia with multisystem abnormalities: "new" features raising nosological problems.

A 32-year-old female presented with progressive external ophthalmoplegia (PEO) and multisystem abnormalities, strikingly associated with myotonia and muscle hypertrophy. These two features were not found in her brother, who had a complex neuromuscular disorder complicating chronic PEO. In both subjects muscle biopsy revealed "ragged-red" fibres and myofibres containing glycogen granules, which were never bound by membranes. A severe demyelinating neuropathy was revealed by electrophysiological and morphological studies. Cranial CT scan showed extensive demyelination of the cerebral white matter. Genetic studies demonstrated that this familial syndrome is transmitted as an autosomal recessive trait.

Adult↗
PubMed1978

Central core disease: histochemical and ultrastructural study of muscle biopsies of father and daughter.

Two cases of central core disease, father and daughter, of a family with dominant autosomal inheritance, are presented, one with bilateral congenital dislocation of the hip. Muscle biopsy was performed in both cases. Oxidative enzymes evidenced only type I fibers, most of them presenting a central core and not uncommonly more than one. On electron microscopy the cores generally appeared well demarcated from the surrounding fibrils and were characterized by lack of mitochondria and abnormalities of the Z line. Transitional aspects from normal fibers to completely unstructured cores were observed, as well as from well structured and unstructured cores. These findings are discussed in the light of the previous literature and particular attention is paid to the problem of differentiation between central core and multicore disease. The pathogenesis of the muscular alteration is also discussed in relation with the possibility of their neurogenic origin. Eventually, the histochemical and ultrastructural similarities between central cores and target fibers are focused.

Biopsy↗