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M Baiget

Publications and source records attributed to M Baiget.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1993

[Clinical manifestations of myotonic dystrophy: epidemiologic survey].

BACKGROUND: The presence of a local aggregation of cases of myotonic dystrophy (MD) allows the evaluation of clinical symptoms of the disease in a sample in which the influence of a possible genetic heterogeneity is decreased. METHODS: The degree of global neuromuscular handicap and the incidence and severity of four of the most characteristic symptoms (cataracts, myotonia, muscular weakness and neuropsycologic disturbances) were studied in 183 patients with MD (146 typical adult forms, 19 neonatal, and 18 partial syndromes) in relation with the age of onset of the symptomatology or length of disease. RESULTS: Only 8.3% of the patients (excluding the neonatal forms) were severely handicapped, and the degree of neuromuscular handicap depended fundamentally on the age of onset of the disease. Cataracts and myotonia were present in 87 and 89% of the patients, respectively. Almost all the patients above the age of 40 presented cataracts. No clinical or subclinical evidence of neuromuscular involvement was present in 11% of the patients with MD. These patients principally corresponded to the group in whom the disease initiated over the age of 50. CONCLUSIONS: The age of onset of the symptomatology appears to be the determining factor to establish both the global prognosis of neuromuscular incapacity of patients with myotonic dystrophy and the explanation of the chronology of the appearance of the most characteristic symptoms of the disease. The presence of carriers without neuromuscular symptomatology is of note, this fact reinforcing the need to incorporate DNA examination in the evaluation of asymptomatic relatives or with exclusive ocular symptomatology.

Adolescent↗
PubMed1993

[Direct genotypic analysis of myotonic dystrophy: detection of an unstable DNA fragment in carriers].

BACKGROUND: Myotonic dystrophy (DM) is an inherited autosomal dominant disorder. The molecular defect responsible for the disease is the expansion of a CTG triplet at the 3' end of the DM gene. We report the analysis of the gene expansion, its correlation with the clinical severity and with the phenomenon of anticipation. METHODS: Using the cDNA25 probe, we have analyzed 140 affected DM patients from a total of 42 families comprising 303 individuals. According to the clinical status, the affected DM patients were classified as follows: group I, congenital form; group II, classical form, and group III, mild form. RESULTS: A larger than normal fragment was detected in all the DM patients but in none of the controls. The expansion size is 2.5-6 kb in group I, 0.3-5 kb in group II and 0.2-1.5 kb in group III. In 49 parent-child couples which show clinical anticipation, 47 have an increase in size of the fragment from one generation to the next. CONCLUSIONS: Our results show a clear correlation between the severity of the disease and the expansion size. We confirm at the molecular level the phenomenon of anticipation. The direct gene analysis of the DM families allows the diagnosis of all the at-risk individuals and facilitates the genetic counselling of these families.

Adult↗
PubMed1993

Molecular diagnosis of homozygous myotonic dystrophy in two asymptomatic sisters.

The genetic defect underlying myotonic dystrophy (DM) has been identified as the expansion of an unstable trinucleotide repeat sequence, and this discovery has led to new approaches to diagnosis and genetic counselling in families with the disorder. We report the genetic analysis of a consanguineous DM family in which two asymptomatic sisters had been shown to be homozygous for the 'at risk' haplotype. PCR analysis of the region spanning the trinucleotide expansion demonstrated that both sisters possessed two alleles with repeat sizes normally seen in minimally affected patients. Extensive clinical examination failed to demonstrate any of the symptoms of DM in these women. The implications of this finding, both for understanding the disease mechanism, and for genetic counselling in such situations are discussed.

Adolescent↗
PubMed1993

Prevalence of myotonic dystrophy in Guipúzcoa (Basque Country, Spain).

Prevalence figures for inherited neuromuscular disorders are important both for health care planning purposes and for evaluating the need for DNA diagnostic services for eugenic approaches. We screened for the prevalence of myotonic dystrophy (MyD) through extensive inquiry of neurologic and primary health services of Guipúzcoa (Basque Country, northern Spain) between 1989 and 1991. Typical adult-onset and neonatal cases and relatives at risk; suffering from a partial syndrome, were included. In the latter, molecular typing was performed with DNA probes close to the MyD gene to demonstrate the MyD gene carrier status. The high prevalence detected (26.5 cases per 100,000 population) could be explained by methodological factors, but intrinsic factors, such as a possible founder genetic effect or the quick growth of the Guipúzcoa population since the last century may contribute to one of the highest MyD prevalence in the world. In the future, the methodological basis for epidemiologic surveys of MyD must combine molecular technology with more-extensive family inquiries.

Humans↗
PubMed1992

Parental origin and germline mosaicism of deletions and duplications of the dystrophin gene: a European study.

Knowledge about the parental origin of new mutations and the occurrence of germline mosaicism is important for estimating recurrence risks in Duchenne (DMD) and Becker muscular dystrophy (BMD). However, there are problems in resolving these issues partly because not all mutations can as yet be directly detected, and additionally because genetic ratios are very sensitive to ascertainment bias. In the present study, therefore, analysis was restricted to currently detectable mutations (deletions and duplications) in particular types of families which tend to be rare. In order to obtain sufficient data we pooled results from 25 European centers. In mothers of affected patients who were the first in their family with a dystrophin gene deletion or duplication, the ratio between the paternal and the maternal origin of this new mutation was 32:49 (binomial test P = 0.075) for DMD. In five BMD families the ratio between paternal and maternal origin of new mutations was 3:2. Recurrence risk because of maternal germline mosaicism was studied in sisters or subsequent sibs of isolated cases with an apparently new detectable mutation. In 12 out of 59 (0.20; 95% CI 0.10-0.31) transmissions of the risk haplotype the DMD mutation was transmitted as well. No recurrences were found in nine BMD families.

Chromosome Deletion↗
PubMed1992

Linkage disequilibrium detected between myotonic dystrophy and the anonymous marker D19S63 in the Spanish population.

We used the following polymorphic markers: APOC2 (BanI, BglI, TaqI), CKMM (NcoI, TaqI), and D19S63 (PstI) to haplotype 33 Spanish myotonic dystrophy (DM) families. We analysed the allele and haplotype frequencies of our sample, and the possible association of alleles or haplotypes with the disease. We found a slight linkage disequilibrium between APOC2 (BanI) and DM, but no disequilibrium when using all other APOC2 and CKMM RFLPs; this agrees with data previously reported. In addition, we found a very strong linkage disequilibrium when using D19S63 (PstI), the + allele being associated with the DM locus. This disequilibrium in the Spanish population indicates that D19S63 is very close to the DM locus.

Alleles↗
PubMed1992

Expansion of the myotonic dystrophy gene in Italian and Spanish patients.

Myotonic dystrophy results from expansion of a (CTG)n repeat at the 3' untranslated region of the myotonin-protein kinase gene. We show here the genomic analysis of 322 symptomatic patients with the cDNA-25 probe detecting disease specific EcoRI restriction fragments. The expansion was found in the majority of Italian and Spanish patients (92%). The implications of these results for the detection of symptomatic patients in southern Europe are discussed.

Adult↗
PubMed1991

3' creatine kinase (M-type) polymorphisms linked to myotonic dystrophy in Italian and Spanish populations.

Linkage analysis and haplotype characterization for the allelic system detected at the 3' creatine kinase muscle type (CKMM) locus were carried out in 59 myotonic dystrophy (DM) families from Italy and Spain. A maximum lod score (zmax) of 21.26 at a recombination frequency (theta) of 0.00 was found. No statistically significant linkage disequilibrium was observed between DM and the RFLPs examined. However, a substantial linkage disequilibrium was found between CKMM-TaqI and CKMM-NcoI sites in these two populations.

Alleles↗
PubMed1991

[Application of the polymerase chain reaction technique (PCR) to the molecular diagnosis of myotonic dystrophy].

We report the application of the PCR technique to study the CKMM polymorphisms in 39 Spanish Myotonic Dystrophy affected families. We have studied 255 subjects comprising 116 clinically affected DM patients. The molecular study was informative in 64% of the DM patients. For the 76 at risk individuals, the study was informative in 46 of them, confirming the non carrier status in 34 individuals and demonstrating the at risk haplotype in 12. In the remaining 30 subjects, it was not possible to establish a diagnose with this technique exclusively. The use of the CKMM probe in the DM genetic studies was extremely useful because of the close linkage with the gene (1 cM) and the high heterozygosity (PIC = 0.33). The allelic frequencies detected by the TaqI enzyme (allele I = 0.27; allele i = 0.73) and NcoI enzyme (allele J = 0.29; allele j = 0.71) are similar to the previously reported in other european populations.

Base Sequence↗
PubMed1990

[Prenatal diagnosis of myotonic dystrophy: the first experience in Spain].

We report the first prenatal diagnosis of myotonic dystrophy (MD) in Spain by DNA techniques. The previous familiar study allowed us to determine the DM haplotype in this family with the following probe/enzyme combinations: p4.1/Msp I, LDR 152/Bgl II, Apo CII/Ban I, Taq I, Bam HI, pSCII/Bgl I. In the tenth week of amenorrhea, a transabdominal biopsy was done to obtain chorionic villi. One part of the sample was processed for the cytogenetic analysis that revealed a 46 XY karyotype. The other part was used to perform the molecular analysis with two probes, p4.1 and LDR 152, determining that the fetus was a DM gene carrier with a 96% probability.

Family Health↗