[Prenatal diagnosis by amniocentesis. Clinical and cytogenetic experience in 1,500 cases]. / Diagnóstico prenatal por amniocentesis. Experiencia clínica y citogenética en 1,500 casos.

BACKGROUND: Genetic amniocentesis is performed in México 25 years ago but only few works have been published. OBJECTIVE: To analyze clinical and cytogenetic findings in consecutive patients submitted to genetic amniocentesis. MATERIAL AND METHOD: An analysis was made of the clinical features, amniocentesis results and pregnancy outcome in 1500 consecutive cases of genetic amniocentesis. RESULTS: Sixty-eight fetuses with chromosomopathy (4.5%) were detected and two, with an inborn error of metabolism. The most frequent abnormalities were trisomy 21 (32 cases), trisomy 18 (10 cases), trisomy 13(6 cases), 45,X (6 cases), 47,XXY (4 cases). Pregnancy outcome is known in 474 patients (32%). There were five fetal losses (1%). Of the 68 cases with chromosomopathy, the outcome is known in 45, of which, 29 (64%) decided to have an abortion while 16 (35%) continued the pregnancy, six had a spontaneous abortion or perinatal death and ten had an alive new born. Among fetuses with normal or balanced karyotype and normal ultrasound, 11 out of 419 (2.6%) had congenital anomalies. Two of them had a condition known to be related with epigenetic regulation, (Russell Silver and Angelman syndrome). CONCLUSIONS: Amniocentesis is a reliable and low risk method. Cytogenetic findings in this series are similar to those reported in the literature. Most patients with fetal disease decided to have an abortion. The finding of two patients with a condition related with abnormal epigenetic regulation suggests that the magnitude of this risk remains to be defined.

Fetal Niemann-Pick disease type C: ultrastructural and lipid findings in liver and spleen.

We present the first ultrastructural study of liver and spleen from a 20-week fetus with Niemann-Pick disease type C in correlation with lipid studies of these tissues. The lipid storage pattern was characteristic of the disease and although the distribution of the lipid storage was similar to that of affected children, ultrastructural studies emphasized that many inclusions were qualitatively different. These are discussed. Concomitant with this complex lipid storage, ultrastructural evidence of cholestasis was observed and the early hyperplasia of pericanalicular microfilaments leads us to question the presence of a toxic metabolite which might induce cholestasis by acting upon microfilaments.

Niemann-Pick disease type B: first-trimester prenatal diagnosis on chorionic villi and biochemical study of a foetus at 12 weeks of development.

First-trimester prenatal diagnosis of Niemann-Pick disease type B was successfully achieved by sphingomyelinase assay on chorionic villi, performed directly and after 3 weeks' culture. Cultured chorionic cells were normally found to exhibit sphingomyelinase activities 3 times higher than seen in the solid biopsy, and showed a lower residual activity in the affected foetus. Their study may thus prove helpful in dubious cases. Enzyme activities and lipid patterns were studied in several organs of the aborted foetus. Lysosomal sphingomyelinase was deficient in all tissues. The lipid pattern of the brain was normal for the age, but a 4-fold sphingomyelin storage had already taken place in the liver (2.5-fold in the spleen) of this 12-gestational week foetus.

Prenatal diagnosis and fetal pathology of Niemann-Pick disease.

Prenatal diagnosis was successfully accomplished by determining sphingomyelinase activity in the cultured amniotic fluid cells in a case of high risk pregnancy for Niemann-Pick disease (NPD), type A. No detectable activity of sphingomyelinase was found in the cultured amniotic fluid cells obtained at the 17th week of gestation. Patient's pregnancy was terminated and the aborted fetus was proved to be affected with NPD. The liver, brain and skin fibroblasts from the aborted fetus revealed a markedly diminished activity of sphingomyelinase. Sphingomyelin content in the liver of the affected fetus was found to be increased approximately sevenfold as compared with that in a control fetus liver. On the other hand, there was no increase of sphingomyelin in the brain from the affected fetus. No significant increase in cholesterol content was found in the liver and brain from the affected fetus. Electron-microscopic findings revealed membranous cytoplasmic bodies and electron dense material with vacuoles in cytoplasm of the liver cell and a number of Zebra body-like inclusions in the cerebral vessel wall. Biochemical and histological findings of the NPD fetus indicate that there is the progress of the disorder already in the midtrimester of gestation.