Effect on risk of anencephaly of gene-nutrient interactions between methylenetetrahydrofolate reductase C677T polymorphism and maternal folate, vitamin B12 and homocysteine profile.

OBJECTIVE: To evaluate the effects on anencephaly risk of the interaction between the maternal profile of folate, vitamin B12 and homocysteine and the 677C→T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR). DESIGN: Case-control study paired (1:1) on maternity clinic, date of birth and state of residence. Cases of anencephaly were identified using the Registry of the Mexican Neural Tube Defect Epidemiological Surveillance System. Case and control mothers were selected from the same maternity departments. All mothers completed a structured questionnaire and blood samples were obtained to determine the MTHFR 677C→T polymorphism and biochemical profile. SETTING: Mexico, Puebla and Guerrero states, Mexico. SUBJECTS: A total of 151 mothers of cases and controls were enrolled from March 2000 to February 2001. We had complete information on biochemical profile and MTHFR C677T polymorphism for ninety-eight mothers of cases and ninety-one mothers of controls. RESULTS: The adjusted models show that the risk of anencephaly in mothers with 677TT genotype was reduced by 18 % (OR = 0·82; 95 % CI 0·72, 0·94) for each 1 ng/ml increment in serum folate. In terms of tertiles, mothers with 677TT genotype with serum folate levels in the upper tertile (>14·1 ng/ml) had a 95 % lower risk to have a child with anencephaly than mothers with serum folate levels in the first and second tertiles (P trend = 0·012). CONCLUSIONS: Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677C→T polymorphism and folate status. We observed a protective effect on anencephaly risk only in mothers with 677TT genotype as serum folate levels increased.

Prenatal diagnosis in a cystic fibrosis family: a combined molecular strategy for a precise diagnosis.

INTRODUCTION: The high genetic heterogeneity in populations with a wide spectrum of mutations in the CF transmembrane conductance regulator gene (CFTR), makes the detection of mutations a very hard and difficult task, thereby limiting the accurate diagnosis of the disease, mainly in patients with uncharacterized mutations. MATERIAL AND METHODS: Molecular strategies, like targeted identification of the most frequent CFTR mutations in Mexican population combined with linkage analysis using markers, is very useful for carrier detection and for prenatal diagnosis in affected families with CF. In this paper we show that the combination of methodologies was a crucial alternative to reach a precise prenatal CF diagnosis. We documented CF diagnosis in a 14th-week fetus combining the screening of the most common mutations in Mexican population with linkage analysis of two extragenic polymorphisms (XV2C/TaqI and KM19/PstI). RESULTS: We determined that the fetus inherited the PG542X mutation from its mother and an unknown mutation from its father through the chromosomal phases analysis.

[Alpha-fetoprotein as an early predictor of adverse perinatal outcome]. / Alfa fetoproteína como predictor temprano de desenlace perinatal adverso.

BACKGROUND: The alpha-fetoprotein (AFP) is a glycoprotein, which is produced by the human fetus. Previous studies have shown associations between elevated AFP levels and an increased risk of adverse perinatal outcomes. OBJECTIVE: To determine if abnormal AFP levels are associated with adverse perinatal outcomes. The AFP concentrations were calculated as Multiples of the medians (MoM). PATIENTS AND METHOD: A prospective cohort study, including 283 pregnant women, the maternal serum concentration of AFP was determined between 15 and 20 weeks of pregnancy, and the pregnancy was followed until term, when we search for the perinatal outcomes. The study was made in the Instituto Nacional de Perinatología, in Mexico City, from August 2007 to January 2008. For the analyses, the AFP concentrations were calculated as Multiples of the medians (MoM). RESULTS: The threshold of 1.5 MoM increases the risk for preterm delivery (RR: 1.77, IC 95%: 1.04-3.03), abruption placentae (RR: 3.67, IC 95%: 1.59-8.49), placenta accreta (RR: 3.67, IC 95%: 1.59-8.49) and for intrauterine growth restriction (RR: 2.86, IC 95%: 1.74-4.68) There was a weak relation between AFP concentration and birth weight (r = -0.12, p = 0.047) and no correlation with pregnancy weeks at birth. CONCLUSIONS: There is a relation between adverse perinatal outcome and abnormal AFP levels. The evidence of an increase in the AFP concentration in fetuses without congenital defects should alert de clinician about the possibility of other adverse perinatal outcomes and those results must be included in the prenatal risk assessment.

[Identificación de fármacos reguladores de la actividad del promotor Egr-1 en fibroblastos humanos transducidos con AdΔegr-1-Luc7]. / Identification of drugs as regulators on the activity of Egr-1 promoter in human fibroblasts transduced with AdΔegr-1-Luc7.

INTRODUCCIÓN: La proteína de respuesta temprana a crecimiento 1 (EGR-1) es un factor de transcripción involucrado en la diferenciación y la proliferación celulares, cuya expresión es regulada por su promotor en respuesta a diversos factores físicos y químicos, y a fármacos. Aquí se describen algunos de los principales efectos de los fármacos esteroides y del factor de crecimiento epitelial 1 (EGF-1) sobre la actividad del promotor, mediante un sistema reportero transducido por el adenovirus AdΔegr-1-Luc7 en fibroblastos primarios humanos. MÉTODO: Los fibroblastos primarios humanos fueron cultivados en pase 5, transducidos con AdΔegr-1-Luc7 y expuestos a betametasona, hidrocortisona, dexametasona, testosterona, beta-estradiol y EGF-1 durante 1, 3 y 6 horas. La actividad de reportero fue cuantificada por luminometría y ajustada a la concentración de proteínas totales. RESULTADOS: La actividad del promotor en presencia de betametasona, hidrocortisona, dexametasona, testosterona y beta-estradiol fue similar a la actividad basal del promotor a las 1, 3 y 6 horas. El control positivo mostró una actividad 17.8 veces mayor a las 6 horas (p ≤ 0.05). De manera similar, las células expuestas a EGF-1 mostraron una actividad 22.07 veces mayor que las células sin fármaco. CONCLUSIÓN: La actividad del promotor Egr-1 en fibroblastos humanos es regulada negativamente por los fármacos esteroides y positivamente por el EGF-1. INTRODUCTION: The early growth response protein (EGR-1) is a transcription factor involved in cell differentiation and proliferation, whose expression is regulated by its promoter in response to various physical, chemical and drug factors. Hereby, we describe some of the main effects of steroid drugs and EGF-1 on promoter activity, through a reporter system transduced by AdΔegr-1-Luc7 in human primary fibroblasts (HPF). METHODS: Human primary fibroblasts transduced with AdΔegr-1-Luc7 were exposed to betamethasone, hydrocortisone, dexamethasone, testosterone, beta-estradiol, and EGF-1 during 1, 3 and 6 h. Reporter assay was quantified by luminometry. RESULTS: The activity of the promoter in presence of betamethasone, hydrocortisone, dexamethasone, testosterone and beta-estradiol were similar to the basal activity of the promoter at 1, 3 and 6 h. The positive control showed an activity 17.8 folds higher (p ≤ 0.05) at 6 h. EGF-1 showed activity of 22.07 folds greater than cells without drug. CONCLUSION: The activity of the EGR-1 promoter in human fibroblasts is negatively regulated by steroid drugs and positively by the EGF-1.

[Pallister-Killian syndrome. Case report]. / Síndrome de Pallister-Killian. Comunicación de un caso.

BACKGROUND: Pallister-Killian syndrome is a rare sporadic genetic disorder with a tissue-specific mosaic distribution of an additional isochromosome 12p [i(12p)]. Due to the low risk of recurrence, prenatal diagnosis of this syndrome is important for the genetic counseling. OBJECTIVE: To report the first prenatal diagnosis case of Pallister-Killian syndrome in Mexico (lethal neonatal presentation associated with hypoplastic left heart). METHODS/RESULTS: We admitted to our hospital a third-trimester, 31-year-old-pregnant woman; the level II sonographic examination showed: polyhydramnios, micromelia, hypoplastic left heart and a fetal facial profile characterized by small nose, thin upper lip and protruding lower lip. We confirmed the diagnosis with cultured amniotic cells. Standard G banding techniques showed a male karyotype with an extra chromosome i(12p) in the 100% of metaphase cells: 47,XY, + i(12p).

[Skin and tissue bank: Operational model for the recovery and preservation of tissues and skin allografts]. / Banco de piel y tejidos: un modelo operativo para la recuperación y preservación de aloinjertos de piel y tejidos.

Tissue storage is a medical process that is in the regulation and homogenisation phase in the scientific world. The international standards require the need to ensure safety and efficacy of human allografts such as skin and other tissues. The activities of skin and tissues banks currently involve their recovery, processing, storage and distribution, which are positively correlated with technological and scientific advances present in current biomedical sciences. A description is presented of the operational model of Skin and Tissue Bank at INR as successful case for procurement, recovery and preservation of skin and tissues for therapeutic uses, with high safety and biological quality. The essential and standard guidelines are presented as keystones for a tissue recovery program based on scientific evidence, and within an ethical and legal framework, as well as to propose a model for complete overview of the donation of tissues and organ programs in Mexico. Finally, it concludes with essential proposals for improving the efficacy of transplantation of organs and tissue programs.

[Prenatal diagnosis in the first trimester, whom and how?]. / Diagnóstico prenatal en el primer trimestre, a quién y cómo?

Since the last decade more screening tests for chromosomal abnormalities are available to all pregnant women in the first trimester. In the same way, more women above 35 years of age are now pregnant. Offering direct invasive procedures to this "high-risk" group should increase the number of fetal losses associated with amniocentesis or chorionic villus sampling (CVS). Different screening procedures could modify the background risk and thus the clinical management. The nuchal translucency (NT) measurement has been the most important factor to detect fetuses at risk of chromosomal abnormalities. A NT above the 95 centile can detect 70% of fetuses with Down syndrome with 5% of false positive rate (FPR). In addition to the NT, maternal serum markers as the free beta human chorionic gonadotropin (beta hCG) and pregnancy-associated plasma protein (PAPP-A) protein can improve the detection rate to 80% with a fixed 5% of FPR. Preliminary reports showed that the combination of NT, maternal serum markers and the evaluation of the nasal bone could detect more than 90% of fetuses with Down syndrome with 5% of FPR. The CVS performed after 10 weeks of gestation has the same risk as the amniocentesis in the second trimester. Placental mosaicism identified by the CVS might be associated with early growth restriction and placental insufficiency. The complete assessment must be offered to all patients at around 11-14 weeks. In cases when a CVS is performed the complete results can be ready in 72 hours.

Molecular screening of the CFTR gene in Mexican patients with congenital absence of the vas deferens.

BACKGROUND: In several populations CFTR mutations, as well as IVS8-Tn CFTR polymorphism, have been associated with congenital bilateral absence of the vas deferens (CBAVD) and idiopathic obstructive azoospermia diseases. However, the involvement of these mutations in infertility of Mexican males has not been elucidated. AIMS: We investigated whether CFTR mutations and IVS8-Tn(TG)m polymorphisms are associated with infertility in azoospermic Mexican patients. METHODS: Sixteen CBAVD and 33 idiopathic azoospermic cases were included. The CFTR gene was sequenced in all CBAVD cases. In the idiopathic azoospermic patients, the p.F508del, p.G542X, p.N1303K, p.S549N, p.I507del, and p.R117H mutations and those detected in our CBAVD cases were screened. RESULTS: The p.F508del, p.G85E, p.D1152H, and p.W1089X mutations were found in 3 CBAVD patients (18.8%). None of the 9 CFTR mutations screened for in idiopathic azoospermic were found; however, we documented a high frequency of the Gln1463Gln polymorphism in comparison with healthy controls (20% vs 6%; p=0.0029). CONCLUSIONS: These data showed that the CFTR mutations but not the IVS8-Tn polymorphism are involved in CBAVD etiology in a Mexican population. Nevertheless, other screening strategies should be used to rule out the implication of CFTR mutations in idiopathic azoospermic disease.

Methylenetetrahydrofolate reductase gene 677CT polymorphism and isolated congenital heart disease in a Mexican population.

INTRODUCTION AND OBJECTIVES: The frequency of the 677C>T mutation in the methylenetetrahydrofolate reductase gene in Mexico is one of the highest worldwide. Some studies have shown that both the homozygous state of this mutation and a high homocysteine concentration are associated with congenital heart disease. The aim of this study was to determine whether this association exists in the Mexican population. METHODS: Genotypes were analyzed in 60 patients with congenital heart disease and in their mothers, and the levels of homocysteine were determined in the latter group. The genotypes were compared with those of a control group (n=62) and of their mothers. All the possible mother-child genotype combinations were also compared. RESULTS: There were no significant differences in allele or genotype frequencies between the patients with congenital heart disease and the controls or their respective mothers (P>.05). Although no significant differences were observed when the homocysteine concentrations in the presence of the CC or the TT genotype were compared, a clear trend was observed (P=.0621). We found no significant differences in homocysteine concentrations in relation to folic acid intake. The study cases and controls did not differ in terms of the possible combinations of mother-child genotypes. CONCLUSIONS: The frequencies obtained were consistent with those reported for Mexico. No significant differences were found between groups. Nor did we find any association between TT mutations in both the mother and child and hyperhomocysteinemia. There was no evidence of an association between any of the mother-child genotype combinations and congenital heart disease. Similar studies with larger numbers of patients are required to confirm or refute some of the trends observed in this report.

Inside the outbreak of the 2009 influenza A (H1N1)v virus in Mexico.

BACKGROUND: Influenza viruses pose a threat to human health because of their potential to cause global disease. Between mid March and mid April a pandemic influenza A virus emerged in Mexico. This report details 202 cases of infection of humans with the 2009 influenza A virus (H1N1)v which occurred in Mexico City as well as the spread of the virus throughout the entire country. METHODOLOGY AND FINDINGS: From May 1st to May 5th nasopharyngeal swabs, derived from 751 patients, were collected at 220 outpatient clinics and 28 hospitals distributed throughout Mexico City. Analysis of samples using real time RT-PCR revealed that 202 patients out of the 751 subjects (26.9%) were confirmed to be infected with the new virus. All confirmed cases of human infection with the strain influenza (H1N1)v suffered respiratory symptoms. The greatest number of confirmed cases during the outbreak of the 2009 influenza A (H1N1)v were seen in neighbourhoods on the northeast side of Mexico City including Iztapalapa, Gustavo A. Madero, Iztacalco, and Tlahuac which are the most populated areas in Mexico City. Using these data, together with data reported by the Mexican Secretariat of Health (MSH) to date, we plot the course of influenza (H1N1)v activity throughout Mexico. CONCLUSIONS: Our data, which is backed up by MSH data, show that the greatest numbers of the 2009 influenza A (H1N1) cases were seen in the most populated areas. We speculate on conditions in Mexico which may have sparked this flu pandemic, the first in 41 years. We accept the hypothesis that high population density and a mass gathering which took in Iztapalapa contributed to the rapid spread of the disease which developed in three peaks of activity throughout the Country.

Identification of influenza A pandemic (H1N1) 2009 variants during the first 2009 influenza outbreak in Mexico City.

BACKGROUND: In March 2009, public health surveillance detected increased numbers of influenza-like illness presenting to hospitals in Mexico City. The aetiological agent was subsequently determined to be a novel influenza A (H1N1) triple reassortant, which has spread worldwide. As a consequence the World Health Organisation has declared the first Influenza pandemic of the 21st century. OBJECTIVES: To describe clinically and molecularly the first outbreak of influenza A pH1N1 (2009) during 1-5 May to establish a baseline of epidemiological data for pH1N1. Also, to monitor for the emergence of antiviral resistance, and mutations affecting virulence and transmissibility. STUDY DESIGN: Samples were collected from 751 patients with influenza-like symptoms throughout Mexico City and were tested for influenza A pH1N1 (2009) using real-time PCR. In the samples that were positive for influenza A pH1N1 (2009) fragments from the haemagglutinin (H1) and neuraminidase (N1) genes were sequenced. RESULTS: A total of 203/751 (27%) patients were positive for the pandemic H1N1 (2009) virus (53% male and 47% female). The 0-12-year-old group was the most affected 85/751 (42%). Sequence analysis showed five new variants of the pandemic H1N1 (2009) virus for NA: G249E (GQ292900), M269I (GQ292892), Y274H (GQ292913), T332A (GQ292933), N344K (GQ292882), and four variants for HA: N461K (GQ293006), K505R (GQ292989), I435V (GQ292995), I527N (GQ292997). CONCLUSIONS: We have provided a baseline of epidemiological data from the first outbreak of influenza A pH1N1 (2009) during 1-5 May in Mexico City. The sequencing of partial fragments of the HA and NA genes did not show the presence of previously described mutations affecting known sites of antiviral resistance in seasonal influenza A such as the H275Y (oseltamivir resistance), R293 or N295 etc.

45,X/47,XXX/47,XX, del(Y)(p?)/46,XX mosaicism causing true hermaphroditism.

Sex differentiation in humans depends on the presence of the Y-linked gene SRY, which is activated in the pre-Sertoli cells of the developing gonadal primordium to trigger testicular differentiation. Occasionally testicular formation can take place in subjects lacking a Y chromosome resulting in a 46,XX sex reversal condition. True hermaphroditism (TH) is a rare form of intersexuality characterized by the presence of testicular and ovarian tissue in the same individual. Genetic heterogeneity has been proposed as a cause of dual gonadal development in some cases and recently, hidden mosaicism was reported to cause TH in some 46,XX SRY negative patients. Here we report a TH case in which hidden mosaicism for the Y and X chromosome was detected by PCR and FISH in peripheral blood and gonadal tissue, supporting the fact that mosaicism may cause TH and that molecular analysis of gonadal tissue should be performed in all 46,XX cases.

Trascendencia de los factores ambientales y genéticos en cardiopatías congénitas: el caso de la enzima MTHFR / Significance of enviromental and genetic factors related to congenital heart diseases: MTHFR enzyme case

Las cardiopatías congénitas (CC) en México son la tercera causa de muerte en niños menores de un año y la sexta en niños de tres años de edad. En su etiología las CC presentan una heterogeneidad genética, y en su mayoría son de herencia multifactorial. Se considera que las CC y los defectos de tubo neural (DTN) son las entidades más comunes de origen multifactorial. Se ha reconocido que la pobre ingesta de ácido fólico es uno de los factores ambientales que se relacionan con los DTN, así como la presencia del polimorfismo C677T de la enzima metiltetrahidrofolato reductasa (MTHFR), lo que lleva a un aumento de la homocisteína en sangre. Dada la relación entre algunos procesos de desarrollo cardiaco y del tubo neural, se cree que la enzima MTHRF puede participar en la génesis de las CC. Al respecto, se han realizado estudios acerca de cómo la ingesta de multivitamínicos, disminuyen el riesgo de CC en 24% de los casos, asociada con polimorfismo C677T de la MTHFR en pacientes con CC y aumento de homocisteína en líquido amniótico y plasma en madres de los pacientes con CC. Estudios en biología experimental sustentan que el aumento en los niveles de homocisteína tiene un efecto teratógeno que provoca DTN y CC, entre otras malformaciones. El presente artículo revisa la información acerca de la posible relación entre el polimorfismo C677T, la homocisteína y el desarrollo de CC y plantea la posible prevención de las CC a través del control de la ingesta de ácido fólico.

Congenital heart diseases (CHD) represent the third and sixth cause of death for children of less than a year and three years old respectively in Mexico. There is a very high degree of heterogeneity for CHD, having most of them multifactorial inheritance. CHD and neural tube defects (NTD) are the most common entities with this type of inheritance. It has been recognized that poor folic acid intake and the presence of C677Tpolymorphism on the MTHFR gene are both important environmental and genetic factors related to NTD development, through the rise of circulating blood homocysteine levels. Based on the close embryonic relationship at some processes between cardiac and neural tube development, it is thought that MTHFR enzyme could be actively involved on CHD development. Furthermore, different studies have demonstrated that there is a 24% risk reduction for CHD development when multivitamin intake schedule is followed even on the presence of C677T MTHFR polymorphism. At the same time, rises on homocysteine concentrations in mothers of patients affected by CHD, have been noticed in amniotic fluid as well as maternal plasma. Experimental Biology studies show that rises on homocysteine levels have a teratogenic effect producing NTD, CHD and some other malformative events. This paper, review how information regarding the possible relation between C677T MTHFR polymorphism, homocysteine levels and CHD development, in an attempt to establish possible preventive measures for CC through folic acid intake.

Análisis y resultados clinicocitogenéticos de fetos y recién nacidos con alteraciones cromosómicas durante un año en el Instituto Nacional de Perinatología / Analysis of clinical and cytogenetic studies fetus and new born with chromosomal anomalies during one year at the Instituto Nacional de Perinatología

Introducción: Las anormalidades cromosómicas son una causa frecuente de morbilidad y mortalidad en la población humana. Objetivo: Describir el número y tipo de las alteraciones cromosómicas numéricas y estructurales detectadas en estudios citogenéticos realizados prenatalmente y en recién nacidos en el Instituto Nacional de Perinatología (INPer) durante el periodo comprendido de enero a diciembre del 2003. Metodología: Realizar un estudio descriptivo de tipo retrolectivo de los pacientes revisados por el Departamento de Genética con defectos congénitos que presentaron anormalidades cromosómicas. Resultados: Durante el año 2003, 3.26% (189/5795) de los pacientes nacidos en el INPer presentaron defectos al nacimiento, de los cuales veintisiete pacientes mostraron un cariotipo anormal de los cuales 21 (77.7%) presentaron alteraciones cromosómicas numéricas; además, en seis (22.2%) se encontró una alteración cromosómica estructural, lo que representa 0.46% de los pacientes nacidos en el INPer. En seis casos el diagnóstico se realizó en etapa prenatal y se corroboró al nacimiento. Conclusiones: La mayoría de alteraciones cromosómicas se presentan con múltiples defectos al nacimiento y con alteración en el crecimiento y desarrollo mental. Es importante que ante la presencia de pacientes con múltiples defectos mayores estructurales se sospechen este tipo de alteraciones y se realicen los estudios necesarios a la familia para poder brindar un adecuado asesoramiento genético.

Introduction: Chromosomal anomalies are a frequent cause of human disease. Objective: Describe the numerical and structural chromosomal anomalies detected by cytogenetic studies done prenatally and in newborns found in the Instituto Nacional de Perinatología during the period between January and December 2003. Methods: Descriptive study of the patients with congenital defects seen by the Genetics Department who presented chromosomal anomalies. Results: During the year 2003, the 3.46% (189/5795) of the babies born at the INPer had structural anomalies. Twenty patients had a chromosomal anomaly of which 21 (77.7%) had a chromosomal numeric alteration and six (22.2%) a chromosomal structural anomaly which represented 0.46% of the newborns. In six cases the diagnosis was done prenatally and confirmed at birth. Conclusions: Most of the chromosomal anomalies present themselves with multiple congenital anomalies and retarded growth and development. It is very important to implement this type of studies in patients with congenital anomalies, complete the familiar study and provide an accurate genetic counseling to the parents.

Niveles de ácido fólico, homocisteína y polimorfismo de la enzima metilentetrahidrofolatorreductasa (MTHFR) en pacientes con preeclampsia severa y eclampsia / Folic acid levels, homocysteine and metilentetrahidrofolatorreductase polimorfism in severe preeclampsia and eclampsia

Objetivo. La preeclampsia y eclampsia, son la principal causa de mortalidad materna. En el estado de Nuevo León de 1990 a 1998, estas patologías representaron 44.1 por ciento. La presencia de sustancias con actividad trombogénica en la sangre materna (homocisteína, proteína C y anticuerpos anticardiolipina) han sido relacionadas. El polimorfismo C677T de la enzima metilentetrahidrofolatorreductasa (MTHFR) favorece la elevación de la homocisteína, la suplementación con ácido fólico (AF) disminuye sus niveles. Se pretende establecer el papel que el AF tiene en la fisiopatología de la preeclampsia en nuestro medio. Tipo de estudio. Longitudinal, prospectivo y comparativo. Materiales y métodos. Casos: mujeres con preeclampsia severa y/o eclampsia (n=13). Controles: mujeres con embarazo normoevolutivo en el tercer trimestre (n=15). Se tomaron 20 mL de sangre en las primeras 24 horas del puerperio midiendo AF, homocisteína y polimorfismo de la MTHFR. Para comparaciones entre ambos grupos se utilizó la preba de t de Student y exacta de Fisher. Resultados. Los valores de homocisteína fueron (xñDE): Casos 9.85 micromol/L ñ 2.88 y controles 7.61 micromol/L ñ 1.32 (p<0.04). La frecuencia ( por ciento) del polimorfismo genético de la MTHFR fue: homocigotas positivas (T/T): 38.46 vs 20, heterocigotas (C/T): 38.46 vs 26.6, homocigotas negativas (C/C): 23 vs 53, para casos y controles respectivamente. Conclusiones. En nuestro estudio el estado homocigoto (T/T) de la MTHFR y los valores elevados de homocisteína en sangre son más frecuentes en mujeres con preeclampsia.

Factores de riesgo en la etapa intrauterina que predisponen a la luxación congénita de cadera / Risk factor in intrauterine stage, that predispose to congenital dislocation of the hip

La luxación congénita de cadera es uno de las patologías más frecuentes en la etapa neonatal en la que se interactúan una serie de factores para su presentación algunos de estos factores pueden ser identificados desde el periodo prenatal e incluyen la presentación pélvica, el sexo y la cantidad de líquido amniótico, además la luxación puede ser parte de un complejo sindromático que presenta también una serie de alteraciones agregadas, el seleccionar a la población con un mayor riesgo puede conducir a una evaluación mas detallada al nacimiento e iniciar las maniobras terapéuticas para una corrección temprana

A case of mosaic Down's syndrome with two Robertsonian translocations

Una niña con síndrome de Down mostró mosaicismo con dos diferentes línes celulares: 45,XX,der(14q;21q)/46,XX,der(21q,21q)+21. Los arreglos cromosómicos detectados en esta paciente aparentemente surgieron de novo. Se discuten cuatro mecanismos para explicar el origen del mosaicismo: disociación de una translocación cromosómica (14q;21q) presente en un cigoto 45,XX,der(14q,21q); dos translocaciones secuenciales en la primera y segunda divisiones del cigoto (46,XX); una translocación entre cromátides en un cigoto 47,XX,+21; y un origen independiente de las dos líneas celulares

Enfermedad poliquística en una familia mexicana: revisión de la literatura / Polycystic disease in Mexican family: review of the literature

Los estudios genéticos de familias con enfermedad poliquística renal autosómica son escasos, no obstante que es una de las alteraciones hereditarias más frecuentes. Este padecimiento se debe a una mutación en el genoma del locus PKD1 localizado en el brazo corto del cromosoma 16. Esta alteración se ha calculado en una proporción de 1:1000. Se informa de seis pacientes pertenecientes a una familia mexicana studiada en un lapso de 45 años. Existe un periodo muy largo asintomático entre el principio del padecimiento y la etapa final. Después de los 30 años aumenta el diagnóstico de los quistes tanto en número como en tamaño. Para el diagnóstico, es de gran utilidad el ultrasonido como procedimiento fácil, económico y que emplea energía no ionizante. El tratamiento quirúrgico temprano de los quistes renales previene o retarda la etapa final de insuficiencia renal crónica.

Utilidad de los marcadores ultrasonográficos de cromosomopatía / Usefulness of ultrasonographic markers of chromosomopathy

Durante un periodo de tres años y medio, en 132 mujeres embarazadas se diagnosticó la presencia de una amplia variedad de anomalías morfológicas fetales, sugestivas de cromosomopatía, utilizando un equipo de ultrasonido de alta definición y la participación multidisciplinaria. En 95 casos se realizó amniocentesis para estudio del cariotipo fetal. En esta población se determinó la incidencia de cromosomopatía, su contribución al total de las alteraciones cromosómicas diagnosticadas en el periodo de estudio y la expresión fenotípica de las diferentes aneuploidías. Se encontraron 29 cariotipos fetales anormales; 11 con tisomía 18, siete con monosomía del X, cuatro trisomía 21, tres con trisomía 13, uno tetraploidía (29xxyy), uno con mosaico para Turner (45XO 68 por ciento, 46XY 32 por ciento) y dos con inversión en el cromosoma nueve. Del total de las cromosomopatías diagnosticadas en el mismo periodo (N=50), el grupo con anomalías morfológicas representó 49.2 por ciento, mientras que las otras poblaciones de riesgo, de cinco a 15 por ciento. Se diagnosticaron 224 anormalías morfológicas, 43 (19 por ciento) aisladas y 181 (81 por ciento) asociadas. Un número de 80 (36 por ciento) se presentaron en las cromosomopatías. Los marcadores que tuvieron mayor asociación fueron la atresia duodenal, la cardiopatía, la microcefalia, la fosa posterior amplia y el higroma quístico. Se encontró un patrón de marcadores específicos para cada alteración cromosómica. Se concluyó que el ultrasonido puede ser el método más útil para seleccionar el grupo de embarazadas con mayor riesgo de cariotipo anormal