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Biomedical subjects

A S Breed

Publications and source records attributed to A S Breed.

16 recordsLinked to original sources
PubMed1993

Tetrasomy 5p mosaicism in a boy with delayed growth, hypotonia, minor anomalies, and an additional isochromosome 5p [46,XY/47,XY, + i(5p)].

We describe a 1-year-old boy with a rare de novo 46,XY/47,XY, + i(5p) mosaicism (ratios 28/3 in peripheral blood lymphocytes and 2/12 in skin fibroblasts). The boy, born after a pregnancy of 34 weeks, had lung hypoplasia, persistent hypotonia, and postnatal growth failure. Craniofacial anomalies were also present. His clinical manifestations correspond to those described in trisomy 5p patients. Prenatal diagnosis on maternal age indication had shown normal male chromosomes in 16 cells in the short term culture of a chorionic villus sampling. Retrospectively, 1 out of 217 cells in this culture showed the i(5p). Several mechanisms could have resulted in the formation of this 46/47, + i(5p) mosaic. Postzygotic local incorrect ligation during chromatid replication, followed by a second replication offers an attractive model on theoretical grounds since it needs only one step to explain both isochromosome formation and mosaicism. Differences between the various tissues in selection pressure on cells with the isochromosome might explain the different ratios of mosaicism found.

Aneuploidy↗
PubMed1993

[Serum screening of pregnant women for fetal neural tube defects and Down syndrome; initial experiences in The Netherlands].

OBJECTIVE: To examine if, and if so, in what way, the maternal serum screening for fetal neural tube defects (NTD) and Down's syndrome (DS) in the Dutch decentralized obstetrical organization would be feasible and effective. DESIGN: Prospective. SETTING: University Hospital Groningen. METHOD: Between October 1st 1990 and December 1st 1991 we determined the likelihood of a baby with a NTD and/or DS in 2580 pregnant women, at 15 to 20 weeks gestation, by serum screening. RESULTS: Five foetuses with DS were detected, as well as two with a NTD, one foetus with an omphalocele, and one with Turner's syndrome. One infant with a NTD and one with DS were not found prenatally. Of all 98 women of 36 years or older, 68 declined amniocentesis because their risk was lower than the age related risk. CONCLUSIONS: Maternal serum screening for NTD and DS is feasible and effective in principle. In a decentralized prenatal care system, special attention has to be paid to the time needed to report the results and to the completion of the follow-up. The detection rate of DS in pregnant women of 36 years or older remains almost the same, but a significant number of them decline prenatal diagnosis. An increased risk of foetal DS, determined by serum screening, should be added to the official list of indications for prenatal diagnosis in the Netherlands.

Adolescent↗
PubMed1993

Evidence of a second gamete fusion after the first cleavage of the zygote in a 47,XX,+18/70,XXX,+18 mosaic. A remarkable diploid-triploid discrepancy after CVS.

A 70,XXX,+18 karyotype was found by chorionic villus sampling, while the fetal fibroblast culture of the affected fetus revealed a 47,XX,+18 karyotype. From several possible mechanisms, we assume that a second gamete fusion occurred after the first cell division of the zygote. According to this interpretation, the mosaicism arose in very early pregnancy (at the two-cell stage). This discrepancy can therefore be explained by selection pressure, due to the differentiation processes in the embryonic tissues.

Adult↗
PubMed1993

Down syndrome: effects of demographic factors and prenatal diagnosis on the future livebirth prevalence.

In northwest European countries maternal age is increasing. This will lead to an increase of the prevalence of Down syndrome conceptuses. Meanwhile, the increased use of prenatal cytogenetic diagnosis (PCD) will lead to a decrease in the prevalence of Down syndrome among livebirths. We were interested to know what the result of these two opposite developments would be in the near future, and we describe here a model to quantify these processes and the resulting livebirth prevalence of Down syndrome. The model is demonstrated for The Netherlands from 1992 to 2001. The predicted livebirth prevalence for The Netherlands in 1992 is 1.36 per 1000. Demographic factors will cause an increase to 1.76 per 1000 in 2001 with present indications for PCD and a utilization ratio of 50%. An increase of the utilization ratio to 90% in 2001 will lead to a prevalence of 1.22 per 1000, a little less than the present prevalence. Alternative screening programs, including maternal serum screening, could lead to a further decrease of the livebirth prevalence. The model described here can be used for evaluation of the consequences of alternative forms of Down syndrome screening.

Birth Rate↗
PubMed1993

Piebaldism in a mentally retarded girl with rare deletion of the long arm of chromosome 4.

A 4-year-old mentally retarded girl had congenital depigmentations of ventrolateral parts of the chest, abdomen, and legs. She also showed dysmorphic features of the head, thorax, and extremities, a pigmented ring in both irises, and a hernia of the left obliquus muscle. Cytogenetic investigations revealed deletion of chromosome 4 for the long arm segment q12-q21. The typical depigmentations, reported in four other patients with a similar chromosomal deletion, correspond with those in the autosomal dominant piebald trait. Mutations in the Kit protooncogene (mapped to the chromosome (4q11-4q12 region) have been found in patients affected with this dominant disorder. Piebaldism in children with developmental delay and dysmorphic features should alert the physician to the possibility of a deletion of the long arm of chromosome 4.

Abnormalities, Multiple↗
PubMed1991

[Opinion of primiparae on the possibility of sex selection].

Recent medical-technological developments such as chorionic villi sampling and in vitro fertilization make sex selection in principle possible. The literature and our own experiences suggest an increasing demand for it. We interviewed a selected group of 180 women regarding sex selection, of whom 127 responded. More than 80% of these rejected a selection based on sex. The legitimacy of withholding information about the sex of the foetus is questionable. The existence of a demand, however small, should prompt professionals to take a stand about its acceptability.

Abortion, Induced↗
PubMed1991

Follow-up and pregnancy outcome after a diagnosis of mosaicism in CVS.

In 2103 consecutive diagnostic chorionic villus samples, examined in a 4-year period in our clinical genetics unit, 26 samples (1.2 per cent) presented chromosomal mosaicism in the direct and/or long-term culture preparations. Only once (46,XX/47,XX,+9) was the mosaicism confirmed in the fetus. In the cytogenetic follow-up studies of the remaining 25 pregnancies, in no cases could the aberration be confirmed in amniotic fluid or fetal tissue. One patient requested a termination after the CVS result. Of the remaining 24 pregnancies, four (16.7 per cent) ended in a spontaneous abortion. These findings suggest an association between placental mosaicism and fetal loss.

Abortion, Spontaneous↗
PubMed1991

Alpha-fetoprotein in fetal serum, amniotic fluid, and maternal serum.

In order to gain more insight into the association between alpha-fetoprotein (AFP) and fetal chromosomal disorders, especially Down's syndrome, we measured AFP in fetal serum, amniotic fluid, and maternal serum at cordocentesis. We compared the concentration and gradient of AFP in these three compartments. Our data confirm earlier findings on second-trimester fetal serum AFP concentration. The results indicate that low maternal serum AFP in pregnancies with fetal chromosomal disorders could result from an impaired fetal kidney function as well as from impaired membrane or placental passage of AFP, rather than from reduced fetal AFP production.

Amniotic Fluid↗
PubMed1990

[Down syndrome in the northeastern Netherlands; expectations and reality 1981-1986].

Down syndrome is caused by presence in triplicate of (a part of) chromosome 21, usually on the basis of a standard trisomy-21. The risk of a child's having a standard trisomy-21 depends on the mother's age. On the basis of the maternal age distribution and age-specific risks, the expected number of neonates with Down syndrome born in 1981-1986 in the EUROCAT region North-East Netherlands is calculated. The number of neonates with Down syndrome registered with EUROCAT does not differ to a statistically significant extent from the expected number. The influence of the rising age-specific fertility in women over 28 years of age and the effect of the moving-up of the increasingly large birth cohorts 1945-1965 are discussed. If the uptake rate for prenatal cytogenetic diagnosis remains constant, these factors will in the next few years lead to an increase of the prevalence of Down syndrome among full-term infants.

Down Syndrome↗
PubMed1990

The predictive value of cytogenetic diagnosis after CVS: 1500 cases.

The cytogenetic results of 1500 chorionic villus samples (CVS) are presented. In these 1500 samples, 23 samples (1.5 per cent) could not be provided with a diagnosis because of laboratory failure. This failure rate dropped from 3 per cent in the first 500 samples to 0.2 per cent in the last 500. In the remaining 1477 samples, 58 (3.9 per cent) chromosomal aberrations were found. Of these, 21 (36 per cent) proved not to represent the karyotype of the fetus proper. Predictive values of (different groups of) chromosomal aberrations in CVS are calculated. The impact of (differences between) the predictive value for some major chromosomal aberrations is discussed. A tissue- and chromosome-specific selection mechanism is postulated.

Chorionic Villi Sampling↗
PubMed1990

Paracentric inversion inv(11)(q21q23) in The Netherlands.

We report the result of investigations from 20 families with 72 carriers of the paracentric inversion inv(11)(q21q23) in the Netherlands. There is no increase in the rate of spontaneous abortions among carriers of the inversion or their partners. Also, so far, there are no children with recombinant chromosomes arising from the inversion. It is doubtful whether prenatal diagnosis would be helpful to carriers of this inversion. The results of the genealogy study and geographical distribution are discussed; it is suggested that all the families have arisen from a single mutation.

Abortion, Spontaneous↗
PubMed1988

Partial duplication 14q/deletion 2q in two sibs due to t(2;14) (q37.1;q31.2) pat.

Two siblings are described with duplication 14q/deletion 2q due to a paternal translocation (2;14) (q37.1;q31.2). The first one, a boy, born at term, lived 14 days. The second one, a female foetus, was born after induced labour when the anomaly was discovered by way of amniocentesis. They both had almost identical phenotypes. From a study of the literature it is inferred that a typical asymmetric head form, low set abnormal ears, micrognathia, long upper lip, rib anomalies, camptodactyly, long fingers and contractures are prominent features of the syndrome.

Abortion, Induced↗