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R Lisker

Publications and source records attributed to R Lisker.

At least 19 recordsLinked to original sources
PubMed1999

Mexican geneticists' views of ethical issues in genetics testing and screening. Are eugenic principles involved?

Herein we discuss Mexican geneticists' views of ethical issues in genetic testing and screening, analyzing whether eugenic principles are involved in this activity. The information was obtained from a comprehensive survey on genetics, ethics, and society organized by Wertz and Fletcher in 1993, in which 37 nations participated. The responses to 21 questions from 64 out of 89 (72%) geneticists invited to participate are analyzed in this paper. The questions were practically the same as those answered recently by a group of Chinese geneticists (Mao X. Chinese geneticists' views of ethical issues in genetic testing and screening: evidence for eugenics in China. Am J Hum Genet 1998: 63: 688-695), who work in a country where the furtherance of eugenic principles is considered to be the goal of human genetics. We concluded that although there are many similarities in the answers from both countries, this is not indicative of Mexican geneticists pursuing eugenic goals because: a) there is no coercion involved; and b) there is no intention of improving the gene pool.

China↗
PubMed1998

Attitudes of Mexican geneticists towards prenatal diagnosis and selective abortion.

Prenatal diagnosis (PD) provides the physician information on whether the unborn fetus has a genetic or chromosomal disorder, and offers patients a new option: selective abortion. In the present study, we analyzed the answers Mexican geneticists provided to a few selected questions from a multinational survey designed by Wertz and Fletcher [1988: Am J Hum Genet 42:592-600]. The selected questions were related to the use of PD, the acceptance of selective abortion, and the self-reported directiveness of counselling following the diagnosis of a fetal anomaly. Our results show that the great majority of Mexican geneticists participating in the study agree with PD when medically indicated, but not on free demand. Specific cases stimulated the group on thinking more than the general statements provided in the survey. Although the majority agreed that PD should be available to all women, when faced with cases of nonmorbid maternal anxiety, paternity testing, and sex selection, the proportion of geneticists willing to perform the test decreased substantially. When counselling patients on a fetal anomaly, the minority would be as unbiased as possible, and this seems to be the tendency in developing countries where counselling, as stated in the respondents' comments, reflects the belief that the goal of genetics is the prevention of or opposition to abortion. Counselling was influenced by the severity of the disorder. The geneticists' personal attitude toward abortion in the same situations was stronger than when counselling others. Analysis of directiveness in counselling for fetal anomaly showed that older geneticists, with more years of experience in medical genetics, were more likely to be neutral. When counselling directively, the group showed an overall direction toward continuing affected pregnancies. However, older geneticists and those with more than 10 years of practice were more likely than their younger counterparts to counsel towards terminating affected pregnancies. In personal situations of fetal disorder, the general tendency was to abort; however, geneticists seeing more than 5 patients per week, and those who believe that religion is important, were more likely to reject abortion. The sample is representative of Mexican geneticists, and the main limitation of this study is that the geneticists have very little experience in PD, and that their responses were mostly based on theory. However, their opinions may influence the demand and the availability of PD and abortion, as well as the possibility of legalization of abortion on the basis of a fetal defect.

Abortion, Induced↗
PubMed1998

Mexican geneticists' opinions on disclosure issues.

Here we discuss the opinion on disclosure issues (respect for confidentiality) of Mexican professionals working in clinical genetics. The information was obtained from a comprehensive survey on genetics, ethics and society organized by Wertz and Fletcher in 1993, in which geneticists from 37 nations participated. The responses to 18 questions from 64 of 89 (72%) geneticists invited to participate were analyzed for this paper. The questions were directed to investigate: a) disclosure of clinically relevant information in several situations such as testicular feminization syndrome, mosaic de novo balanced translocation in a fetus, or accidental discovery of non-paternity; b) the protection of patient's privacy from the spouse or blood relatives; and c) confidentiality in cases with high genetic risk to relatives. The results reveal significant disparity between general responses related to disclosure of all clinically relevant information and specific responses in particular cases. In addition, professionals appear to give higher priority to protecting the spouse, blood relatives or public safety, rather than the patient's confidentiality.

Attitude of Health Personnel↗
PubMed1997

Counselling following diagnosis of a fetal abnormality: comparison of different clinical specialists in Mexico.

Most geneticists agree that counselling should be nondirective, and studies report that genetic counselling by geneticists is performed largely in a neutral style. However, couples at risk of having a child with a genetic condition may seek the advice of other physicians. The purpose of the present study was to describe the answers of four groups of specialists from Mexico City (internists, pediatricians, obstetricians, and neurologists) regarding how they would counsel a couple when prenatal diagnosis has shown that a fetus is affected by one of 17 different genetic disorders and to analyze the role of several variables in the development of their opinion. Our results show that physicians in these specialties are more likely to counsel directively than neutrally. Other variables did not influence the directiveness. With respect to direction of influence, internists, pediatricians, and neurologists are more likely to counsel terminating affected pregnancies than are obstetricians (P = 0.0002). Similarly, clinicians older than 37 years of age and those reporting that religion is not important to them counsel terminating affected pregnancies (P = 0.005 and P = 0.003, respectively). Physicians' gender and clinical experience with genetic diseases did not show statistically significant differences. Strong consensus among specialists was reached only on terminating pregnancies in anencephaly. A lowered and moderate consensus (51-75% agreement) was reached on continuing pregnancies with cleft lip and plate. A moderate measure of consensus for nondirective counselling was found among obstetricians regarding 14 of the 17 diseases in the study, whereas neurologists expressed a moderate measure of consensus on counselling the termination of pregnancies when the fetus was affected by neurological disorders. Hence, the approach to counselling was related in part to the fetal condition and in part to the clinician's specialty and age and the self-reported importance of religion. The data presented herein may not be representative of all Mexican physicians within the selected specialties; however, it is important to gather their opinions because they are involved in the care and treatment of genetic diseases and may have an important influence on the demand and availability of prenatal diagnosis and abortion.

Abortion, Induced↗
PubMed1997

Attitudes of Mexican physicians toward induced abortion.

The objective of this study was to analyze physicians' attitudes towards induced abortion with normal fetuses and fetuses known to have an abnormality in various degrees. A total of 193 physicians (internists, pediatricians, gynecologists and neurologists) answered a self-administered questionnaire. The questions were about voluntary abortion; voluntary abortion with malformed fetus; abortion because the fetus has anencephaly; and two questions were asked for the use of prenatal diagnosis and abortion in case of the fetus being the physician's child. The majority of physicians were male, over 35 years, religious and did not have experience with genetic diseases. Few physicians approved abortion of a normal pregnancy, 6 out of 10 agreed if the fetus was malformed, and this number increased to 8 or 9 out of 10 in cases of severe or lethal genetic disease. Gynecologists and neurologists were less in agreement with abortion when pregnancy is normal than the internists and pediatricians (7% vs. 20%). In general the physicians did not have consistent answers. Agreement for abortion was influenced by religious values.

Abortion, Induced↗
PubMed1997

HLA class I and class II alleles and haplotypes in Mexican mestizos established from serological typing of 50 families.

We describe new information on the frequency and association of class II antigens (HLA-DR and HLA-DQ) of the major histocompatibility complex (MHC) in Mexicans. The study includes HLA-B typing and its association with the HLA-DR antigens determined in 50 families, which included 100 individuals. This family study allowed the establishment of the precise composition of the 200 HLA haplotypes, which cannot be obtained from unrelated individuals. The predominant antigens in decreasing order of frequency were B35, B39, and B61 at the B locus; DR4, DR5, and DR8 at the DR locus; and DQ3 at the DQ locus. The most common HLA-B,HLA-DR haplotype (considering broad specificities) was B16,DR4, with a frequency of 8.0%. Five HLA-B,HLA-DR haplotypes showed significant delta values (observed vs. expected frequencies) after correcting for the number of comparisons. On the other hand, the most common HLA-DR,HLA-DQ haplotypes were DR4,DQ3 and DR5,DQ3 with a frequency higher than 10%. Ten of the 17 HLA-DR,HLA-DQ haplotypes had significant postcorrection delta values.

Ethnicity↗
PubMed1996

Genetic structure of autochthonous populations of Meso-America: Mexico.

We analyze the possible effect of gene flow on the genetic structure of present-day Mexicans. For this purpose we reviewed previous admixture estimates for various Indian and Mestizo groups. Several facts seem clear: (1) There are no pure Indian groups in Mexico, because all Indian groups show variable degrees of admixture, mostly with whites (range, 0.088 in the Huichol to 0.373 in the Huasteco); (2) the main ancestral contribution to the noncoastal lower middle class Mestizo populations is Indian (above 50%) so that from a genetic standpoint Indians and lower middle class Mestizos are not much different; and (3) black ancestry is quite high on the coasts, ranging from 0.127 to 0.405 on the east coast, and is present in other Mestizos, ranging in large urban centers from 0.027 in Oaxaca to 0.107 in Puebla and in smaller cities from 0.08 in Tlaxcala to 0.181 in Cuanalán.

Emigration and Immigration↗
PubMed1996

[Heredity of poor digestion of lactose].

The published reports on the possibility that the adult type of lactose maldigestion is a hereditary condition are reviewed. The ethnic variability in the frequency of this trait, together with twin and family studies, suggest that this is indeed the case. Family studies, including the one performed in Mexico, indicates that the adult type of lactose maldigestion is inherited in an autosomic recessive manner.

Adult↗
PubMed1994

Red cell acid phosphatase types and GC polymorphisms in Mérida, Oaxaca, León, and Saltillo, Mexico.

Red cell acid phosphatase types and GC polymorphisms were studied in Mérida and Oaxaca, Mexico. GC polymorphisms were also investigated in León and Saltillo. The ACP*A, ACP*B, and ACP*C gene frequencies were 0.215, 0.770, and 0.015 respectively, in Mérida and 0.205, 0.788, and 0.002, respectively, in Oaxaca. In Oaxaca the ACP*R gene had a frequency of 0.005. The results are similar to other Mestizo groups studied in Mexico; it is concluded that the ACP*C and ACP*R genes were introduced by admixture of native Amerindians with whites and blacks, respectively. The GC*1S, GC*1F, and GC*2 gene frequencies were 0.489, 0.289 and 0.222, respectively, in León; 0.500, 0.272, and 0.228, respectively, in Mérida; 0.454, 0.337, and 0.209, respectively, in Oaxaca; and 0.505, 0.356, and 0.139, respectively, in Saltillo. These results are similar to what has been obtained in other Mestizo populations and Indian groups in Mexico, probably because the main ethnic component in both is Amerindian.

Acid Phosphatase↗
PubMed1992

Distribution of ADH2 and ALDH2 genotypes in different populations.

The distribution of the human liver alcohol dehydrogenase, ADH2, and aldehyde dehydrogenase, ALDH2, genotypes in 21 different populations comprising Mongoloids, Caucasoids, and Negroids was determined by hybridization of the amplified genomic DNA with allele-specific oligonucleotide probes. Whereas the frequency of the ADH1(2) allele was found to be relatively high in the Caucasoids, Mexican Mestizos, Brazilian Indios, Swedish Lapps, Papua New Guineans and Negroids, the frequency of the ADH2(2) gene was considerably higher in the Mongoloids and Australian Aborigines. The atypical ALDH2 gene (ALDH2(2)) was found to be extremely rare in Caucasoids, Negroids, Papua New Guineans, Australian Aborigines and Aurocanians (South Chile). In contrast, this mutant gene was found to be widely prevalent among the Mongoloids. Individuals possessing the abnormal ALDH2 gene show alcohol-related sensitivity responses (e.g. facial flushing), have the tendency not to be habitual drinkers, and apparently suffer less from alcoholism and alcohol-related liver disease.

Alcohol Dehydrogenase↗
PubMed1991

Molecular differentiation of two different translocations producing two apparent Ph chromosomes in a patient with CML.

A case of chronic myelogenous leukemia (CML) is described whose leukemic cells appeared to contain two Philadelphia (Ph) chromosomes originating from different translocations involving the two chromosomes 22. The karyotype of the affected cells, established on two different occasions, was: 46,XY,t(9;22)(q34;q11),t(15;22)(p11;q11) with no normal chromosomes 22 and only one 9q+ in each of 115 marrow cells examined. The same findings were present in 50 peripheral blood cells cultured without phytohemagglutinin (PHA) stimulation. When stimulated with PHA, a normal male karyotype was present in the 11 cells examined. There were no additional chromosomal abnormalities and no indication of a blastic crisis after nearly 1 year following the original study. Analysis of the breakpoint cluster region (bcr) on chromosome 22 in the DNA of the affected cells (marrow) revealed evidence for one rearranged chromosome 22 and one normal chromosome 22, indicating that the t(15;22) was not due to the usual Ph translocation seen in CML. The results point to the crucial usefulness of molecular analysis in confirming cytogenetic results related to Ph translocations in CML.

Adult↗
PubMed1991

Some Mexican glucose-6-phosphate dehydrogenase variants revisited.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency appears to be fairly common in Mexico. We have now examined the DNA of three previously reported electrophoretically fast Mexican G6PD variants, -G6PD Distrito Federal, G6PD Tepic, and G6PD Castilla. All three of these variants, believed on the basis of biochemical characterization and population origin to be unique, have the G----A transition at nucleotide 202 and the A----G transition at nucleotide 376, mutations that we now recognize to be characteristic of G6PD A-. Two other Mexican males with G6PD deficiency were found to have the same mutation. All five have the (NlaIII/FokI/PvuII/PstI) haplotype characteristic of G6PD A -in Africa. Since the PvuII+ genotype seems to be rare in Europe, we conclude that all of these G6PD A - genes had their ancient origin in Africa, although in many of the Mexican patients with G6PD A -202A/376G the gene may have been imported more recently from Spain, where this variant, formerly known as G6PD Betica, is also prevalent.

DNA↗
PubMed1991

[Risk for Down syndrome based on maternal ages grouped in intervals of 2 and 5 years in the Mexican population].

Based on the analysis of 515 patients with Down's syndrome, identified in the Mexican program of Registry and Epidemiological Surveillance of External Congenital Malformations, we obtained the risk at birth for this disease, according to the mother's age, grouped in two and five years intervals. The results confirms other studies suggesting that the risk increases after age 30 and particularly 35. For example the incidence in women 21-22 years old is 0.62 per 1000 births and 40.7 in mothers ages 43-44. The data presented can be utilized for genetic counselling in Mexico and we recommend the use of the biannual figures because they are more precise than the usually employed five years intervals results.

Adolescent↗
PubMed1990

Gene frequencies and admixture estimates in four Mexican urban centers.

We studied 202 individuals from the city of Leon in Guanajuato state, 228 from Merida, Yucatan, 220 from Oaxaca, Oaxaca, and 257 from Saltillo, Coahuila, to learn the distribution of the ABO, MN, Rh, and Duffy blood groups, serum haptoglobin, albumin, and factor Bf types, and red cell hemoglobin and glucose-6-phosphate dehydrogenase types. With the gene frequencies obtained, we performed admixture measurements with a maximum likelihood method, obtaining a trihybrid model for black, Indian, and white ancestry with the following proportions: 0.084, 0.513, and 0.403 in Leon: 0.059, 0.512, and 0.429 in Merida; 0.018, 0.676, and 0.306 in Oaxaca; and 0.073, 0.547, and 0.380 in Saltillo. The general pattern has high Indian ancestry followed by white and black ancestry. This pattern is congruent with most other studies performed in Mexico, including the east coast, where Indian ancestry predominates despite a clear increase in the black contribution.

Blood Group Antigens↗