Prenatal diagnosis of severe osteogenesis imperfecta

The ultrasound findings in a series of 15 prenatally diagnosed cases of severe osteogenesis imperfecta types IIA, IIB, IIC, and III are described, eleven being detected on routine scans of women with no relevant history. As most cases of osteogenesis imperfecta type IIA are dominant sporadic mutations, the importance of prenatal diagnosis during routine scanning at a local level is emphasized. In addition to characteristic broad, shortened and fractured long bones, striking features of the chest and head are highlighted which may be encountered during a routine scan, prompting further assessment.     

Fetal bradycardia in the first trimester: an unusual presentation of atrial extrasystoles

We report a fetus with fetal bradycardia at 13 weeks of gestation secondary to atrial extrasystoles. The fetus subsequently developed paroxysmal supraventricular tachycardia and hydrops fetalis. The cardiac arrhythmia recovered spontaneously without any medical intervention. This case illustrates that atrial ectopic beats can present in the first trimester with fetal bradycardia. Rapidly evolving hydrops fetalis secondary to supraventricular tachycardia can develop, warranting close monitoring with weekly heart rate assessment. Fetal bradycardia secondary to atrial extrasystole should be differentiated from first trimester sinus bradycardia and those associated with major structural cardiac abnormality, which have a high fetal loss rate. Copyright © 2002 John Wiley & Sons, Ltd.     

A comparison of total and free β-HCG assays in Down syndrome screening

Free β-HCG is a new analyte that has been suggested to be superior to total HCG when used in combination with alpha-fetoprotein (AFP) for Down syndrome risk screening in early pregnancy. We have evaluated this claim on 21 samples collected from Down syndrome pregnancies and 180 samples from unaffected pregnancies. The detection rates for the combination of AFP with free β-HCG or the combination of AFP with total HCG were identical (71 per cent) but the initial screen positive rate (equivalent to the false-positive rate) was 7·5 per cent for AFP+free β-HCG screening compared with 3·5 per cent for AFP+ total HCG screening. We conclude that the case for free β-HCG is unproven and suggest that further data be collected before free β-HCG becomes acceptable.     

Cytogenetic experience in prenatal fra(X) detection on amniotic fluid cultures

Since 1987, we have had experience with 13 prenatal diagnoses of 11 women at risk for the fragile X syndrome by cytogenetic studies on amniotic fluid cultures. The induction method included TC 199 medium and methotrexate. Results were obtained in all cases. Ten were males and three were prenatally diagnosed as being affected. Three were females and none of them was fra(X)-positive. Results were confirmed in 10/13 cases. In these cases, we had neither false-positive nor false-negative results.     

Improved performance in a prenatal screening programme for Down's syndrome incorporating serum-free hCG subunit analyses

A prenatal screening programme for Down's syndrome potentially detecting 76 per cent of affected pregnancies in the South Australian general population at an amniocentesis rate of 3.9 per cent was designed following analysis of mid-trimester serum samples from 57 women who carried an affected fetus. This equates to one affected pregnancy being detected for 41 chromosomal analyses performed. For the experimental series, 75.4 per cent of affected pregnancies were detected, while 4.1 per cent of control specimens produced estimated risk odds consistent with further action. A maternal risk odds of birth of a Down's syndrome fetus of 1:420 was taken as the decision value, which is the prevalence of Down's syndrome births to 35-year-old mothers in South Australia. This screening performance was achieved by investigating combinations of serum analytes not previously reported and by refining the calculation of maternal risk odds to include selective weighting of indicator analytes. Combination of the measurements of free α-subunits and β-subunits of chorionic gonadotrophin, α-fetoprotein, unconjugated oestriol, and placental lactogen was found to be most effective in indicating Down's syndrome fetuses. In all combinations of analytes tested, replacing the measurements of free α-subunits and free β-subunits of chorionic gonadotrophin with the measurement of intact chorionic gonadotropin produced a less effective screen.     

Biomass systems and environmental degradation in an Himalayan village

Summary Detailed analyses of the utilisation of the natural forest and its forest products by the community of a small Indian Himalayan village, reveal various interactions between the forest, the people, their agricultural systems and their methods of animal husbandry. Biomass flow systems have been identified and processes of forest and environmental degradation described.     

Development of non-invasive fetal DNA diagnosis from maternal blood

Several attempts have been made to detect and retrieve fetal nucleated cells including nucleated erythrocytes (NRBCs), leukocytes, and trophoblasts in maternal blood. We have recently developed a new method for non-invasive fetal DNA diagnosis from maternal blood. Peripheral blood granulocytes including NRBCs were isolated by a discontinuous density gradient method using Percoll (Pharmasia). NRBCs were found and retrieved at a single cell level using a micromanipulator under a microscope. To determine whether the origin of the NRBCs was maternal or fetal, the NRBCs were analysed by polymerase chain reaction (PCR) amplification to determine the presence of a Y-chromosome-specific repeat sequence in mothers carrying male fetuses. We were successful in predicting fetal sex accurately in 10 out of 11 samples taken from maternal blood. This new technique opens up fetal DNA diagnosis from maternal blood during the first trimester of pregnancy to the whole population because there is no risk to the fetus or the mother.     

Diastrophic dysplasia: A specific prenatal diagnosis by ultrasound

In a pregnant woman without increased genetic risk, the presence of distrophic dysplasia of the fetus was diagnosed sonographically at 31 weeks' gestation and definitively distinguished from other skeletal dysplasias. In all prenatal diagnoses of diastrophic dysplasia reported so far, this autosomal recessive congenital condition had occurred in the family's previous children and this made the diagnoses of fetal diastrophic dysplasia easier. The reported case was diagnosed due to evidence of an extreme shortening of all long bones of the extremities associated with other skeletal deformities which, taken as a whole, are typical of this syndrome: micrognathia, cervical kyphosis, persistent extension limitation in elbow and knee joints, club feet, ulnar diviation of hands, shortened phalanges, and, in particular, abduction of thumbs (‘hitchhiker thumbs’) and big toes.