Biomedical subjects
Publications and source records attributed to B Dallapiccola.
Haplotype data based on the DNA markers closely linked to the cystic fibrosis (CF) gene have been used to correlate the presence of the 3 bp specific deletion (delta F508) in 424 CF chromosomes from 212 Italian CF families. The distribution and the frequency of the F508 deletion on CF chromosomes in our sample suggests the presence of at least a second mutation in the same ancestral haplotype.
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In view of the reported variations of cystic fibrosis (CF) associated haplotypes among populations, a detailed analysis of the distribution of two tightly linked DNA markers (Xv-2c and KM.19) in 18 Italian regions was performed. Haplotypes were determined for 405 CF chromosomes carrying the mutation, and showed significant heterogeneity between the North, Center, and South of Italy and the island of Sardinia. KM.19/PstI Restriction Fragment Length Polymorphism (RFLP) showed significant heterogeneity in these four areas, and was statistically correlated with the geographic distribution of the disease, while Xv-2c/TaqI polymorphism, like the haplotypes of normal chromosomes, was more uniformly distributed over the same four areas. Correlation coefficients between the markers and the mutation have been used to obtain additional indications on the physical distance between the markers and the fibrosis locus.
Enzymatic DNA amplification has become a new important tool in the analysis of human genome. We report the use of this new technique for the detection of a polymorphic DNA sequence adjacent to the Huntington's disease locus for presymptomatic and prenatal testing of the disease.
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We describe three patients, originating from three different Italian localities, affected by the cardio-facio-cutaneous (CFC) syndrome. In addition to a varying degree of mental retardation, these patients present characteristics consisting of a peculiar face with bitemporal frontal constriction and other anomalies involving the eyes, nose, ears, hair, skin, and heart that are consistent with this diagnosis.
Two sibs with the whistling face syndrome, born to unaffected parents, are presented. They had the full facial and limb manifestations typical of this disorder, for which there is evidence of autosomal dominant inheritance. The existence of an autosomal recessive form of this syndrome has been suspected previously on the basis of a limited number of observations. Our study substantiates genetic heterogeneity of this condition and suggests that the autosomal recessive form could be even less rare than is generally considered.
A fetus with an extra idic(X)(q27) was ascertained during prenatal diagnosis. The derived X and one normal X chromosome were late replicating. Due to lack of previous experience, genetic counselling presented obvious difficulties and the fetal phenotype could be only tentatively predicted.
Eight pregnancies at risk for cystic fibrosis have been monitored by first-trimester prenatal diagnosis with DNA amplification analysis. The polymerase chain reaction (PCR) was used in all cases to amplify the region detected by KM19. In two cases, the region detected by CS.7, another DNA probe tightly linked to the CF locus, was also examined. The results of the PCR determinations were confirmed using the Southern blotting procedure, by segregation analysis of restriction fragment length polymorphisms (RFLPs) relative to XV-2c, J3.11, metH, metD, and KM19 probes.
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A (14;21) homozygous Robertsonian translocation was detected by first-trimester prenatal diagnosis. The related parents were heterozygous for the same translocation. At birth the baby was physically normal and had a normal psychomotor development. Together with a few previous observations in living homozygotes for (13;14) translocations, this case corroborates the idea that these subjects with 44 chromosomes are healthy without dysmorphic features.
A prenatal diagnosis of adult polycystic kidney disease by DNA testing is reported. Evidence showing a linkage between the disease and the 3'HVR and 24.1 restriction fragment length polymorphisms (RFLPs) on chromosome 16 was obtained in the proband's family by linkage analysis of data and homogeneity testing with Italian families of the linked type. Fetal genotype prediction based on both flanking markers was confirmed by histological and ultrastructural findings in fetal kidneys.
The action of the iron chelator desferrioxamine (DFO) on the cytogenetic pattern of cultured lymphocytes from Fanconi anemia (FA) patients was investigated. The addition of 10(-4) M DFO throughout the culture time resulted in a 50% reduction of the spontaneous chromosome breakage of FA cells. In addition, the clastogenic action of diepoxybutane on FA lymphocytes was also partly counteracted by DFO. The above findings support the assumption that one of the mechanisms involved in the pathogenesis of FA might be an impaired capacity of the cells from such patients to remove active oxygen species. The relationship between intraleukocyte chelatable iron pool and free radical formation in FA subjects is discussed.
Three polymorphic DNA marker loci (INT1L1, D7S23 and D7S399) map to a chromosomal region that is very close to the cystic fibrosis (CF) locus in terms of genetic distance. These marker loci have been used to analyse the linkage disequilibrium in 137 CF families from two South European countries (Italy and Spain). The markers can be analysed for differences in linkage disequilibrium more easily in these populations than in North Europeans, in whom the disequilibrium between the allelic systems defined by the probes and CF is much greater and on a "plateau" through the genetic region. The different levels of disequilibrium found in the studied populations suggest that D7S399 and D7S23 are both closer to CF than INT1L1, and provide additional information on the origins and homogeneity of the CF defect.
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The effect of hydrogen peroxide on the rate of semi-conservative DNA synthesis in ataxia telangiectasia (AT) and normal human lymphoblastoid cells was investigated. The rate of DNA synthesis in AT cells was not depressed to a lesser extent than in normal cells, as might have been expected since H2O2 is a radiomimetic agent. On the contrary, 4 AT cell lines displayed a higher sensitivity to the inhibitory effect of H2O2 on DNA synthesis than 2 normal cell lines. Comparable levels of cytotoxicity were detected in cell viability studies. Furthermore, neither the level of DNA breakage produced by H2O2, nor the rate of repair of these lesions was significantly different in normal and AT cells. Together, these results indicate that the AT cell lines utilized in this study are not hypersensitive to the oxidant. It is suggested that H2O2 may not induce lethality via the direct action of the hydroxyl radical (OH.).
The features of a newborn with the full clinical aspect of trisomy 9 presenting with an atrioventricular canal is described. This association of anomalies has never been reported before. Interestingly, the patient also had a left-sided obstruction which is known to be more characteristically associated with atrioventricular canal without Down's syndrome.