El diagnóstico prenatal de defectos cromosómicos en Costa Rica: [revisión] / Prenatal diagnosis of chromosomic defects in Costa Rica: [review]

This is an historical overview of prenatal cytogenetic diagnosis in Costa Rica. It started in 1984 at the Institute for Health Research of the University of Costa Rica. This is the only fetal cytogenetic diagnosis facility in the country and serves social security as well as private patients. Perinatologists send amniotic fluid and fetal blood samples from high risk pregnancies, mainly due to abnormal ultrasound assessment, sonographic markers of aneuploidy and advanced maternal age. Second and third trimester diagnosis allows the development of coping strategies for the families of affected fetuses, since pregnancy interruption is not permitted. Normal fetal cytogenetic results provide reassurance to the parents.

Cariotipos fetales mediante amniocentesis y cordocentesis en Costa Rica

Objetivo: Identificar cromosomopatía fetal en embarazos de alto riesgo, así como brindar adecuada atención obstétrica, pediátrica y asesoramiento genético. Material y métodos: En 290 embarazadas se obtuvieron células fetales mediante amniocentesis, realizadas desde enero de 2000 hasta agosto de 2003 inclusive, en hospitales de la seguridad social y en la consulta privada. La indicación de las punciones fue por examen ultrasonográfico anormal en 44% de los casos y por edad materna avanzada en 39%. El 91% de los estudios se realizaron en el segundo trimestre del embarazo. Se utilizó el sistema cerrado de histocultivo y la cosecha por suspensión. El resultado final se obtuvo en 16 días (mediana). Durante el mismo periodo se estudiaron 18 embarazos mediante cordocentesis y cariotipo fetal. La indicación en todos los casos, excepto uno, fue examen ultrasonográfico anormal. Las cordocentesis se realizaron desde la semana 17 hasta la 35. Resultados: Los 230 cariotipos fetales obtenidos en muestras de líquido amniótico fueron anormales en 28 casos (12%). Se encontró concordancia entre el cariotipo y el fenotipo del feto o recién nacido, al igual que entre el diagnóstico ultrasonográfico fetal y la condición del neonato. El cariotipo en muestras de sangre fetal fue anormal en el 27% de los estudios. Conclusiones: La cromosomopatía fetal es la responsable de un buen número de alteraciones sonográficas durante el embarazo y de desenlaces obstétricos desfavorables. Conviene su detección precoz para tratar de minimizar el daño asociado a estos defectos citogenéticos.

Objective: The identification of fetal abnormal chromosomes to allow proper pediatric and obstetric management of the cases as well as genetic counseling. Material and methods: The results of 290 genetic amniocentesis from January 2000 to August 2003, are reported. There were two main reasons for referral: abnormal ultrasound assessment (44% of cases) and advanced maternal age (39%). Most procedures (91%) were performed during the second trimester of pregnancy. Fetal cells were closed cultured and suspension harvested. Turn around time was 16 days median. G banded (300-400 bands resolution) chromosomes from 20 cells provided by two independent cultures were karyotyped in each case. The results of 18 genetic percutaneous umbilical cord samplings from January 2002 to August 2003, are also reported. Almost all procedures were performed due to abnormal ultrasound findings from gestational week 17 to 35. Results: In 230 fetal karyotypes obtained from amniotic fluid, 27 (12%) were abnormal, due to 12 autosomal trisomies , three cases of monosomy X, three mosaics involving chromosome X, three triploid karyotypes, two balanced translocations of maternal origin, one structurally abnormal chromosome and three other defects of sexual chromosomes in males. Prenatal cytogenetic and sonographic findings correlated with the fetal or newborn phenotype in all cases available for follow-up. Fetal abnormal chromosomes obtained from fetal blood were: two cases of trisomy 13, one fetus with trisomy 18, and one case of trisomy 21. Conclusion: Chromosome defects are an important reason for ultrasonographic fetal abnormalities and adverse pregnancy outcomes. Normal results provided reassurance to the parents.