MaryJ. Seller

Possible prevention of neural-tube defects by periconceptional vitamin supplementation.

Women who had previously given birth to one or more infants with a neural-tube defect (NTD) were recruited into a trial of periconceptional multivitamin supplementation. 1 of 178 infants/fetuses of fully supplemented mothers (0.6%) had an NTD, compared with 13 of 260 infants/fetuses of unsupplemented mothers (5.0%).

Further experience of vitamin supplementation for prevention of neural tube defect recurrences

In accordance with a previous protocol, a second cohort of 254 mothers with a history of previous neural tube defect (NTD) births was before a subsequent conception and continued until the time of the second missed menstrual period. There were 2 NTD recurrences (0.9% of 234 infants/fetuses examined), which is significantly fewer than the 11 NTD recurrences (5.1% of 215 infants/fetuses examined) born to 219 unsupplemented (US) mothers in the same centres over the same period. When the data for the two cohorts were combined, the overall recurrence rates were 0.7% for 454 fully supplemented (FS) mothers and 4.7% for 519 US mothers. The recurrence rates after 1 previous NTD were 0.5% for FS and 4.2% for US mothers: after 2 or more previous NTDs, 2.3% for FS and 9.6% for US. There were no recurrences among the offspring of a further 114 mothers whose duration of supplementation fell short of the full regimen (partially supplemented, PS).

EARLY TERMINATION OF ANENCEPHALIC PREGNANCY AFTER DETECTION BY RAISED ALPHA-FETOPROTEIN LEVELS

Abstract Amniocentesis was done on a woman, 18 weeks pregnant, who had had an anencephalic child with spina bifida. The α-fetoprotein (A.F.P.) content of the amniotic fluid was 380 μg, per ml. (normal mean 15·5 μg. per ml.). On sonography no fetal head could be detected. The pregnancy was terminated at 20 weeks, and a fetus with anencephaly was delivered. This suggests that anencephaly can be diagnosed in utero by studying the A.F.P. at a stage early enough in pregnancy to permit termination.

ULTRASOUND IN THE DIAGNOSIS OF SPINA BIFIDA

Three patients who were at risk of having a baby with a neural-tube defect were investigated by ultrasonic examination and alpha-fetoprotein (A;F.P.) estimation. In all three cases amniotic-fluid A.F.P. levels were significantly raised and pregnancy was terminated. In the first case ultrasound failed to detect a small lumbo-sacral meningocele; In the second case ultrasound successfully diagnosed a dorso-lumbar meningo-myelocele but did not recognise internal hydrocephalus. In the third case ultrasound did not define any lesion, and pathological examination of the fetus revealed no abnormality. It is concluded that ultrasonic examination is an important diagnostic technique in the antneatal investigation of spina bifida.

MATERNAL SERUM-ALPHA-FETOPROTEIN LEVELS AND PRENATAL DIAGNOSIS OF NEURAL-TUBE DEFECTS

Abstract Maternal serum-alpha-fetoprotein (A.F.P.) levels were compared throughout pregnancy in women bearing fetuses with severe neural-tube defects and in control women. From the second trimester onwards, the former group had higher levels than the controls, but the difference was not always clear-cut, rendering such a test less reliable than assay of the amniotic-fluid A.F.P. The blood-A.F.P. levels of seven anencephalic fetuses were normal for their gestational age, suggesting that there is no increased synthesis of A.F.P. in fetuses with severe neural-tube defects.

PRENATAL SCREENING FOR DOWN SYNDROME

Points to note • Should you have any private dating ultrasound arranged, please show us for reference. If you already have a Down syndrome screening test performed at a private clinic, it is generally recommended not to repeat the test. • If you would like to undergo other screening or diagnostic tests, you should approach organisations outside the Hospital Authority. • Join one screening program only. If you join more than one screening program, the results may be confusing and may cause unnecessary anxiety. • For twin pregnancy, Down syndrome screening is available only in first trimester. Most pregnancies are normal but about 2% are complicated by congenital anomalies. Down syndrome is one of the anomalies that can be detected before birth. This leaflet is to help you understand Down syndrome, available tests offered by Hospital Authority (HA), and to help you decide whether you want the screening tests for Down syndrome or not.

Further evidence for an intermittent pattern of neural tube closure in humans.

Evidence is presented to support the recent suggestion that human neural tube closure is similar to that observed in mice, and comprises several regionally distinct closure sites rather than being a simple zipping up process. Seven subjects, each with more than one neural tube defect (NTD), are described. Comparative studies of the location of the lesions in relation to the closed parts of the neural tube imply that such NTD could only have come about if there were intermittent closure of the neural tube.

Alphafetoprotein in midtrimester Down's syndrome fetal serum.

Serum alphafetoprotein was estimated in fetuses with and without Downs syndrome or with other chromosome abnormalities from the 17th to the 28th week of pregnancy. In normal fetuses, the AFP level declines steadily during this period. Before 20 weeks, there was no difference in the serum AFP levels of the three groups of fetuses. After 20 weeks, the serum AFP level in cases of Downs syndrome declined more rapidly than normal. This was not observed in fetuses with other chromosome abnormalities. This suggests that low maternal serum alphafetoprotein levels used for prenatal screening for Downs syndrome in the early second trimester cannot be explained by low levels in the Downs fetuses themselves.

Levels of alpha-fetoprotein in amniotic fluids of mice (curly-tail) with neural tube defects.

Mutant curly-tail mice are genetically predisposed to produce offspring with neural tube defects. Estimation of alpha-fetoprotein in the amniotic fluid of fetuses of these mutants has shown that the levels are raised in fetuses with exencephaly and open spina bifida. This suggests that these mice are a valid model for studies of the aetiology and genesis of neural tube defects in man.

Transplantation of allogeneic haemopoietic tissue in adult anaemic mice of the w series using antilymphocytic serum.

Abstract Mice which possess a genetically determined macrocytic anaemia were treated with antilymphocytic serum (A.L.S.) and allogeneic haemopoietic cells. Studies on haemoglobin and chromosome markers showed that, in many animals, implantation and proliferation of this foreign tissue ensued. In mice which had received the A.L.S. for only 7 days before the haemopoietic graft the blood picture became normal, and has remained so for 190 days.