M. Verjaal

Chorionic villi sampling: cytogenetic and clinical findings in 500 pregnancies

The cytogenetic findings were analysed in a series of 500 pregnancies in which chorionic villi sampling was performed. In all cases a direct method was used, karyotyping being successful in 481 cases (96.2%). The main indication for sampling was maternal age over 36 (412 cases; 82.4%). Abnormal laboratory findings resulted in 24 terminations of pregnancy (4.8%); in addition five unexpected balanced chromosome rearrangements were detected. Twelve of 15 cytogenetic discrepancies were detected at amniocentesis, two after termination, and one at spontaneous abortion. Complete follow up data were available for the first 250 patients, among whom nine pregnancies (3.6%) ended in spontaneous abortion before the 20th week. There were no false negative findings. Seventy additional chromosome studies were performed because of failure of chorionic villi sampling or equivocal results, or for confirmation. Counselling before chorionic villi sampling should include the possibility that subsequent amniocentesis may be needed should mosaicism or other unexpected abnormalities be found. The success rate and accuracy of karyotyping chorionic villi samples by the direct method are acceptable but distinctly less than those of karyotyping cultured amniotic fluid cells.

Severe congenital skin defects in a newborn: Case report and relevance of several obstetrical parameters

The clinical, laboratory, histologic and autopsy findings are reported from a live-born male infant with severe congenital skin defects (CSD) who survived for 2 days. The family history revealed consanguinity of the (Turkish) parents. The patient was compared with 10 cases from the literature with the most severe form of CSD. The combination of severe CSD, parental consanguinity and gastrointestinal atresia was found in 3 of these 11 cases, including our own patient. Differentiation from an atypical form of epidermolysis bullosa, complicated by pyloric atresia, is difficult. The mechanism of the (prenatally detected) elevated amniotic fluid alpha 1-fetoprotein (AFP) level is discussed. The finding of a balanced 13q14q chromosome translocation in the infant and his mother is considered a coincidence.

Five familial cases with a trisomy 16p syndrome due to translocation

A clinical description is given of a syndrome present in three postnatally and two prenatal‐ly detected cases with partial trisomy 16p, caused by a familial translocation t(16;21) (pll;q22). The most consistent features of this syndrome are: low birth weight, small head circumference, low‐set ears, palato(gnatho)schisis, micrognathia, thumb‐agenesis or hypoplasia, hypertonia, overlapping fingers, single umbilical artery, and psychomotor retardation. The clinical picture was identical to that described by Roberts & Duckett (1978) for a single case.

The outcome of pregnancies with confined placental chromosome mosaicism in cytotrophoblast cells

Cytogenetic findings and outcome of pregnancy are reported in 108 cases in which confined placental mosaicism (CPM, n=101) or generalized mosaicism (n=7) was found at or after first‐trimester chorionic villus sampling. In all samples, a (semi)direct cytogenetic analysis of cytotrophoblast cells was performed. Two pregnancies with CPM ended in a spontaneous abortion before 28 weeks (1·9 per cent). In 15 cases the pregnancy was terminated: eight cases were shown to be examples of CPM; seven cases can be considered as examples of generalized mosaicism. A normal cytogenetic result was obtained after follow‐up amniocentesis in 88 of the remaining 91 cases. In three cases, no amniocentesis was performed but confirmation of a normal karyotype was obtained in other cells. One of the 91 pregnancies was nevertheless terminated for psychosocial reasons. One child died perinatally and another on the seventh day after birth. The birth weight is known for 89 children; the curve shows a normal distribution. In 11 of these children (12·3 per cent), the birth weight was found to be below the tenth centile. The outcome in a subgroup of eight pregnancies with CPM and involvement of chromosome 13, 16, or 22, however, revealed two fetal losses and four children with a birth weight below the tenth centile (75 per cent).

Human ?-globin maps to pter-p13.3 in chromosome 16 distal to PGP

SummaryFibroblasts from a fetus with an unbalanced karyotype 46(XY),-16,+(16qter-16p13.3::4q31.1-4qter) were found to possess only one allele at the 3′ hypervariable region (3′HVR) close to the α-globin locus and two alleles at the PGP locus. This places the α-globin locus at the very tip of 16p, distal to PGP.

Prenatal diagnosis of Meckel syndrome

SummaryThe three main features of Meckel syndrome are encephalocele, polycystic kidneys, and polydactyly. Prenatal diagnosis of a fetus with Meckel syndrome was made in the 16th week of gestation by means of amniotic fluid alpha1 fetoprotein estimation. The indication for amniocentesis was a previous child with an occipital meningocele and polycystic kidneys. Interpretation of the alpha1-fetoprotein value (240 μg/ml) was difficult due to fetal blood contamination. Prenatal diagnosis is indicated in any pregnancy following the birth of a child with only two major symptoms of Meckel syndrome.

An evaluation of 75 terminations of pregnancy based on abnormal laboratory findings at first trimester CVS

Seventy‐five selective terminations, based on abnormal laboratory findings at first‐trimester CVS, were performed in 1581 consecutive pregnancies. In all cases a (semi‐) direct method of cytogenetic analysis was used. The 75 abortions were analysed in number of ways. Confirmatory studies showed that three cases had to be considered as false‐positive findings, and in one other case the results were inconclusive. Based on literature data, it was estimated that 41 of the 75 pregnancies would have resulted in seriously handicapped children, surviving beyond the age of 1 year, if no termination of pregnancy had taken place. Negative side‐effects of the procedure include: spontaneous abortion of chromosomally normal fetuses due to the CVS procedure itself and the need for a number of secondary amniocenteses (5.1%). The advantage of DNA diagnosis in X‐linked diseases is illustrated by comparing the CVS results with a previously published amniocentesis study.

Prenatal diagnosis of congenital malformations in 500 pregnancies

The organization, techniques used and diagnostic findings of 500 prenatal diagnoses are reported in detail. In 15 cases the pregnancy was terminated because of abnormal laboratory findings. Follow-up of the remaining pregnancies revealed a perinatal mortality of 1.7%, and the risk of an abortion induced by amniocentesis, performed in the 15–16th wk, to be 1–2%. Serious counseling problems arose in 2 cases with trisomy X, in 2 instances of a balanced chromosome translocation and in 1 case of a de novo translocation.

A critical analysis of 75 therapeutic abortions

An analysis is presented of the first 75 therapeutic abortions based on the results of laboratory investigations on midtrimester amniotic samples from 2816 pregnancies. The reasons for the abortions were: chromosome aberration (n = 36), male fetus at risk for X-linked disorder (n = 23), neural tube defect (n = 14), and metabolic disorders (n = 2). An estimation was made of the life expectancy of these 75 fetuses if no termination of pregnancy had taken place. We estimate that a maximum of about 40% of the aborted fetuses would have resulted in malformed children at the age of 1 year, or in boys developing serious disabilities during infancy. Financial (cost-benefit analysis) and psychologic aspects are discussed.

Rapid prenatal diagnosis of HG-PRT deficiency using ultra-microchemical methods

SummaryA previously developed simple ultramicromethod has been used for the rapid prenatal diagnosis of hypoxanthine-guanine phosphoribosyl transferase (HG-PRT) deficiency. The method is based on the incubation of small numbers of visually selected, lyophilized fibroblasts (in the present study five cells per incubation) with radioactive substrate in an end volume of 0.3 μl. Fibroblasts derived from the amniotic fluid of a 15-week male fetus in a heterozygote for the X-linked Lesch-Nyhan syndrome showed a severe degree of HG-PRT deficiency. In total 50 fibroblasts were used. The diagnosis was confirmed upon termination of the pregnancy by the demonstration of HG-PRT deficiency in fetal erythrocytes and cultured skin fibroblasts.