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Biomedical subjects

B Dallapiccola

Publications and source records attributed to B Dallapiccola.

At least 217 records · Page 12Linked to original sources
PubMed1994

Male hypogonadism in myotonic dystrophy is related to (CTG)n triplet mutation.

The Authors considered the relationship between hypogonadism in myotonic dystrophy (MD) and MT-PK gene mutation. Twenty-seven subjects were studied, and the (CTG)n amplification varied from 70 to 1520 (mean 661 +/- 463). Hypergonadotropic-hypogonadism with LH levels of 6.94 +/- 3.87 and FSH 14.54 +/- 9.58 IU/L was present; testosterone still showed normal values (505.7 +/- 376.2 ng/dl), but 44.4% of patients had abnormal serum level less than 250 ng/dl. We found a significant correlation (p < 0.001) between CTG repeat size and levels of both LH and FSH: these findings suggest that the severity of hypogonadism is related to MT-PK gene mutation.

Adult↗
PubMed1994

Cystinuria caused by mutations in rBAT, a gene involved in the transport of cystine.

Cystinuria is a classic heritable aminoaciduria that involves the defective transepithelial transport of cystine and dibasic amino acids in the kidney and intestine. Six missense mutations in the human rBAT gene, which is involved in high-affinity transport of cystine and dibasic amino acids in kidney and intestine, segregate with cystinuria. These mutations account for 30% of the cystinuria chromosomes studied. Homozygosity for the most common mutation (M467T) was detected in three cystinuric siblings. Mutation M467T nearly abolished the amino acid transport activity induced by rBAT in Xenopus oocytes. These results establish rBAT as a cystinuria gene.

Adolescent↗
PubMed1994

Onychotrichodysplasia and chronic neutropenia without mental retardation (ONS): a second case report.

Onychotrichodysplasia, chronic neutropenia and mental retardation syndrome (ONMRS) is a rare autosomal recessive mutation, mostly reported in patients of Mexican ancestry. We describe a second patient with onychotrichodysplasia and chronic neutropenia without mental retardation (ONS). It is unclear if ONS found in the two European patients with normal mental development is due to genetic heterogeneity or variable expressivity of the same syndrome.

Adult↗
PubMed1994

Congenital cardiac defect in a patient with mosaic 45,X/46,XX,i(21q) karyotype.

A baby is described with 45,X/46,XX,i(21q) mosaicism. DNA analysis indicated that the abnormality arose from two independent postzygotic mutations in a 46,XX zygote, involving the paternal chromosomes 21 and X. In agreement with previous reports, most of the clinical dysmorphisms observed were consistent with Down syndrome. Moreover, congenital heart disease consisted of an atrioventricular canal associated with slight hypoplasia of the left ventricle and a mitral anulus, a complex defect including features found in both Down and Turner syndromes.

Chromosome Aberrations↗
PubMed1994

Trisomy 8 syndrome owing to isodicentric 8p chromosomes: regional assignment of a presumptive gene involved in corpus callosum development.

Two patients with trisomy 8 syndrome owing to an isodicentric 8p;8p chromosome are described. Case 1 had a 46,XX/46,XX,-8,+idic(8)(p23) karyotype while case 2, a male, had the same abnormal karyotype without evidence of mosaicism. In situ hybridisation, performed in case 1, showed that the isochromosome was asymmetrical. Agenesis of the corpus callosum (ACC), which is a feature of trisomy 8 syndrome, was found in both patients. Although ACC is associated with aneuploidies for different chromosomes, a review of published reports indicates that, when associated with chromosome 8, this defect is the result of duplication of a gene located within 8p21-pter. Molecular analysis in one of our patients led us to exclude the distal 23 Mb of 8p from this ACC region.

Abnormalities, Multiple↗
PubMed1994

Defective respiratory capacity and mitochondrial protein synthesis in transformant cybrids harboring the tRNA(Leu(UUR)) mutation associated with maternally inherited myopathy and cardiomyopathy.

We studied the physiometabolic effects of a mitochondrial DNA (mtDNA) heteroplasmic point mutation, the A-->G3260 transition associated with maternally inherited myopathy and cardiomyopathy. To eliminate the possible influence of the autochthonous nuclear gene set, we fused myoblast-derived cytoplasts of a patient with a human tumoral cell line deprived of mtDNA (Rho degrees). The presence and amount of the mutant G3260 vs the wild-type A3260 were measured by solid phase minisequencing. We observed a marked reduction of the percentage of mutant mtDNA in the culture system compared with that measured in the donor's muscle biopsy, suggesting the presence of negative selection against the mutation. Furthermore, stable mitotic segregation of the two mtDNA populations was observed in 18 of 19 transformant clones, suggesting the presence of intraorganelle and possibly intracellular homoplasmy in the precursor cells of the donor. Several indexes of mtDNA-related respiratory capacity, including oxygen consumption, complex I- and complex IV-specific activities, and lactate production, were markedly abnormal in the clones containing a high proportion of mutant mtDNA, as compared with those containing homoplasmic wild-type mtDNA, possibly because of impaired mitochondrial protein synthesis. We conclude that (a) the A-->G3260 transition is indeed responsible for the mitochondrial disorder identified in the donor patient, and (b) transformant cybrid system gives direct evidence of the mitochondrial origin of a genetic disorder and should be adopted for the evaluation of the pathogenic potential of the mtDNA mutations.

Adult↗
PubMed1994

Characteristics of intergenerational contractions of the CTG repeat in myotonic dystrophy.

In myotonic dystrophy (DM), the size of a CTG repeat in the DM kinase gene generally increases in successive generations with clinical evidence of anticipation. However, there have also been cases with an intergenerational contraction of the repeat. We examined 1,489 DM parent-offspring pairs, of which 95 (6.4%) showed such contractions in peripheral blood leukocytes (PBL). In 56 of the 95 pairs, clinical data allowed an analysis of their anticipation status. It is surprising that anticipation occurred in 27 (48%) of these 56 pairs, while none clearly showed a later onset of DM in the symptomatic offspring. The contraction occurred in 76 (10%) of 753 paternal transmissions and in 19 (3%) of 736 maternal transmissions. Anticipation was observed more frequently in maternal (85%) than in paternal (37%) transmissions (P < .001). The parental repeat size correlated with the size of intergenerational contraction (r2 = .50, P << .001), and the slope of linear regression was steeper in paternal (-.62) than in maternal (-.30) transmissions (P << .001). Sixteen DM parents had multiple DM offspring with the CTG repeat contractions. This frequency was higher than the frequency expected from the probability of the repeat contractions (6.4%) and the size of DM sib population (1.54 DM offspring per DM parent, in 968 DM parents). We conclude that (1) intergenerational contractions of the CTG repeat in leukocyte DNA frequently accompanies apparent anticipation, especially when DM is maternally transmitted, and (2) the paternal origin of the repeat and the presence of the repeat contraction in a sibling increase the probability of the CTG repeat contraction.

Adolescent↗
PubMed1994

Sister chromatid exchanges in cultured amniocytes exposed to diagnostic ultrasound in vitro.

An in vitro system has been set up to study the possible genetic effects of diagnostic ultrasound (US) on the developing fetus. Amniotic cells were cultured by the in situ technique. Well established clones were exposed to US for various lengths of time using a linear array transducer within a sound transparent apparatus. Cells were then grown in the presence of 5-bromo-2'-deoxyuridine and processed for scoring the number of sister chromatid exchanges (SCE) as the cytogenetic endpoint. There was no linear relationship between the SCE frequency and the duration of US exposure. Variance analysis showed that only interindividual variability was a significant component of total variation. Neither the main effect of treatment nor the interaction effect were statistically significant. The data suggest that US delivered from a diagnostic unit to actively growing cultured fetal cells in a system closely mimicking the conditions of US exposure during amniocentesis does not induce SCE.

Adult↗
PubMed1993

Human elongation factor EF-1 beta: cloning and characterization of the EF1 beta 5a gene and assignment of EF-1 beta isoforms to chromosomes 2,5,15 and X.

We report here the isolation and characterization of a novel human elongation factor-1 beta (EF-1 beta) gene by cDNA selection from YAC mapping on chromosome 5q12-q14. This gene is specifically transcribed in fetal brain and in skeletal muscle and is characterized by a complete sequence homology with previously described EF-1 beta cDNAs. We also assigned the loci for three other EF-1 beta isoforms, to human chromosomes 2, 15 and X. The multiple chromosomal assignments of EF-1 beta loci demonstrates the genetic heterogeneity of human EF-1 beta peptides.

Base Sequence↗
PubMed1993

Parental origin of chromosome 4p deletion in Wolf-Hirschhorn syndrome.

We report on molecular studies in 7 patients with Wolf-Hirschhorn syndrome (WHC) not showing an obvious chromosome 4p deletion. Analysis of a set of polymorphic probes mapping in the 4p16.3 region showed the absence of paternal haplotypes in 5 cases, and maternal haplotypes in 2. These observations corroborate evidence for preferential paternal origin of the de novo 4p chromosome deletion. The overall results of molecular studies suggest that the preponderance of paternally derived WHC could be due, rather than to imprinting of this region, to an excess of structural rearrangements in the male meiosis, related to differences between the mechanisms of sperm and egg production.

Abnormalities, Multiple↗