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Biomedical subjects

V Daher

Publications and source records attributed to V Daher.

12 recordsLinked to original sources
PubMed1992

[The cytogenetics of premature ovarian failure].

Premature ovarian failure is defined as the occurrence of menopause before the age of 40 years. Etiology has been related to genetic, autoimmune or infectious factors, resistance to gonadotropins and others. Forty-seven patients with this diagnosis were referred for cytogenetic analysis. Sixty-eight percent of the cases had a normal karyotype. In 10.7% there was one 45,X cell and they were catalogued as normal. In 15% of the patients there was a mosaicism with normal cell lines and additional 45,X, 47,XXXX and 48,XXXX ones. Two women had a chromosomal constitution 47,XXX. In one 22-year old patient there was a reciprocal balanced translocation 46,X t(X; 18) (q21.2;q22). The presence of different cell lines, including 45,X cells, could explain an accelerated loss of gametes in the ovary. In women with 47,XXX karyotype, fertility problems and premature menopause have been described. The study of the balanced X-autosome translocation with DNA technics could allow to find the molecular basis of the ovarian failure, permitting the direct search of the gene involved at the site of disruption.

Adolescent↗
PubMed1991

[Results of chromosomal studies in 270 couples with reproductive problems].

Cytogenetic study in couples with recurrent reproductive failure allows the detection of structural chromosome anomalies which don't have a phenotypic effect in carriers, but permit the explanation of the production of genetically unbalanced gametes. We present the investigation performed in 270 couples which demonstrated a chromosomal alteration in 9.2% of them. This allows genetic counselling in respect of the importance of the finding, recurrence risk and reproductive alternatives. In 8.6% we found some cellular lines with aneuploidies in sexual chromosomes, which don't represent a such concrete risk.

Adult↗
PubMed1989

[Cytogenetic study of acute and chronic leukemias].

From 1983 to 1987 we studied 30 patients with leukemia searching for chromosomal alterations. Cytogenetic studies of bone marrow showed an abnormal karyotype in 19 (67%). Seven out of 14 cases of acute leukemia presented different chromosomic alterations. The Philadelphia chromosome was found in 11 patients with chronic myeloid leukemia and 3 patients with chronic lymphatic leukemia; a Pseudo-Philadelphia chromosome was present in one patient, this being the first such finding in Chile. Thus, the karyotype is a valuable complementary study not only in chronic myeloid leukemia but also in chronic lymphatic leukemia and the acute lymphoblastic and non-lymphoblastic varieties.

Adolescent↗
PubMedDate not supplied

[Genetic study in twins].

During the period june 1987-January 1988, 35 consecutive pairs of twins born at two maternity hospitals in the northern area of Santiago were studied to search evidence of genetic or other factors which could eventually favour twinning. Sixteen of these pairs were considered to be monozygotic (MZ) after studying five blood group systems (ABO, Rh, MNSs, Duffy and Kidd) applying the method of Smith and Penrose. Maternal age was higher in dizygotic twins (DZ) than in the MZ group (average 30.1 yrs. v/s 26.8 yrs. respectively (p < 0.05). Family history of twinning was positive in 73% of the MZ and in 82% of the DZ twins. The Duffy and Kidd systems were not in Hardy-Weinberg equilibrium due to a deficit of heterozygotes in MZ as well as in DZ twins. There was a significant increase in MS and Ms haplotypes in both groups of twins respect to the Chilean general population (p = 0.01). These results suggest the presence of a genetic determinant that favors the production of twinning of DZ as well as MZ type. A larger number of cases will be required to test this hypothesis.

Blood Group Antigens↗
PubMedDate not supplied

[Clinical and cytogenetic analysis of 257 cases of Down's syndrome].

Among 257 patients with clinical diagnosis of Down's syndrome, 56.4% of male gender, in whom cytogenetic studies were performed, 14 (5.4%) had normal karyotypes and 243 (94.6%) had 21 trisomy. Of these last, 225 (92.6%) had free 21 trisomy, 10 (4.1%) showed mosaics, 8 (3.3%) had translocations. Average maternal age of this sample was significantly higher than that of patients attending the same maternity wards (32.14 vs. 24.85 years) and 41% of Down syndrome's patients came from mothers aged 36 years or more, even though only 9.7% of this country's deliveries proceed from women of that age group. As to seasonal occurrence, the proportions of births which happened in summer almost doubled that of winter (33.1% vs. 16.9%). The frequency of characteristic clinical signs of Down's syndrome was somewhat different than that described for patients from some other countries, for instance: epicanthus, short neck and widening of the space between 1st. and 2nd. toe were more frequent, while Brushfield's spots, depressed occiput, dental anomalies, heart malformations and fissured tongue seemed less frequent. The importance of cytogenetic studies for diagnosis and genetic counseling is stressed.

Chile↗