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PRENATAL DIAGNOSIS OF ANENCEPHALY THROUGH MATERNAL SERUM-ALPHAFETOPROTEIN MEASUREMENT
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PRENATAL DIAGNOSIS OF ANENCEPHALY THROUGH MATERNAL SERUM-ALPHAFETOPROTEIN MEASUREMENT D. J. H. BROCK
University Department of Human Genetics, Western General Hospital, Edinburgh EH4 2HU A. E. BOLTON Medical Research Council
Radioimmunoassay Team, Edinburgh
J. M. MONAGHAN Department of Obstetrics and Gynœcology, Western General Hospital, Edinburgh An
anencephalic pregnancy was first diagnosed by measurement of &agr;-feto-
Sum ary
protein (A.F.P.) in maternal serum at 16 weeks and then 21 weeks of gestation. After confirmation of the diagnosis by amniotic-fluid A.F.P. measurement and ultrasonic and X-ray scan, the pregnancy was terminated. It is suggested that maternal serum-A.F.P. levels may be useful in the screening of large numbers of pregnancies for possible central-nervoussystem malformations.
Introduction IN 1972 Brock and Sutcliffe showed that a-fetoprotein (A.F.P.) concentrations in amniotic fluids of anencephalic fetuses were very much higher than in those from normal fetuses 1 Most of their samples obtained between 26 weeks’ gestation and term, amniotic fluid from a 13-week fetus with spina bifida and one from an 18-week anencephalic fetussuggested that diagnosis based on A.F.P. could be made early enough to allow termination of pregnancy. Subsequently, amniotic-fluid A.F.P. levels have been exploited for the interruption of a number of pregnancies leading both to anencephaly 3,4 and to spina bifida.5,6 A.F.P. crosses the placental barrier and can be detected in maternal serum with a sensitive radioimmunoassay.’ We report an early prenatal diagnosis of anencephaly in which the first indication of abnormality was a raised concentration of maternal serum-
were
but
one
A.F.P. 7835
27 October 1973
Case-report The
patient’s
first pregnancy resulted in
a
normal
male, the second in a premature female with congenital heart lesion, and the third in a stillborn anencephalic. of blood was taken weeks. Seruma minor modification of the double-antibody radioimmunoassay described by Ruoslahti and Seppälä,8 using a purified A.F.P. standard supplied by Dr S. Nishi. At 16 weeks the patient’s serum-A.F.p. was 135 ng. per ml. Mean of thirteen control sera between 14 and 18 weeks’ gestation was 38 ng. per ml., with a range of 13-75 ng. per ml. At 21 weeks the patient’s serumA.F.P. was 445 ng. per ml., while a mean of fifteen control sera between 20 and 23 weeks’ gestation was 65 ng. per ml., with a range of 14 to 121 ng. per ml. Amniocentesis was performed, and amniotic-fluid A.F.P. was found by immunoelectrophoresis to be 240 /g. per ml. (upper limit of normal at 21 weeks is 18 Ag. per ml.).9 An ultrasonic scan and X-ray examination confirmed anencephaly, while revealing that the mother had spina bifida occulta. The pregnancy was terminated by highdose oxytocin infusion, and the fetus found to be a male anencephalic without spina bifida.
During the
a
at
again
next pregnancy 16 weeks’ gestation and A.F.P. was determined by
sample
at 21
Discussion
Although anencephaly and spina bifida are relatively common congenital malformations in the U.K., there is no method of identifying most at-risk pregnancies. If the mother has already had an affected child the risk of repetition, calculated empirically, is about 1 in 20. However, more than 90 % of infants with anencephaly and spina bifida will be born to mothers with no family history of central-nervousAmniocentesis on all early system malformation. pregnancies for the purpose of determining amnioticfluid A.F.P. is out of the question. Although ultrasonic investigation has allowed the diagnosis of anencephaly at 17 weeks’ gestation," it is a specialised technique requiring sophisticated interpretation, and is not yet applicable to a large number of patients. The importance of our finding is that it raises the possibility of screening pregnancies through a determination made on a small amount of maternal blood. The values for the patient’s serum-A.F.p., 135 ng. per ml. at 16 weeks and 445 ng. per ml. at 21 weeks, were both substantially above the limited number of controls chosen on the basis that the outcome of
924 pregnancy was known. Ishiguro and Nishimura 11 give an upper limit of normal for 16 weeks of about 50 ng. per ml. and for 21 weeks of about 80 ng. per ml. Garoff and Seppiilii 12 report upper limits for these two gestations of 200 ng. per ml. and 300 ng. per ml., respectively. It is probable that as further samples are obtained our normal ranges will be somewhat widened. It would be unwise to suggest that maternal serumA.F.P. alone could be used to diagnose anencephaly or spina bifida early in pregnancy. It is not clear whether the raised amniotic-fluid A.F.P. found in these conditions will inevitably be reflected in raised maternal serum levels. Seppala and Ruoslahti have reported a case of meningomyelocele where amnioticfluid A.F.P. was considerably increased while the maternal serum level was normal, though this was at 27 weeks of pregnancy.13 Perhaps more common
will be false-positive results, for increased serumis associated with a number of conditions unrelated to pregnancy-in particular, primary hepatocellular carcinomas but also other carcinomas/5-17 and non-malignant diseases of the liver."-21 In pregnancy, a raised A.F.P. has been demonstrated to be associated with threatened abortion,21 nonspecific cases of fetal distress, and intrauterine death, and is anticipated where there is fetomaternal transfusion.l3 Most of the false-positives unrelated to pregnancy will be eliminated by amniotic-fluid A.F.P. measurement. Where both maternal serum and amniotic-fluid A.F.P. are raised, the obstetrician is as well to be alerted, whether the outcome of the pregnancy be a spontaneous abortion, an intrauterine A.F.P.
death,
or an
anencephalic infant.
We thank Dr S. Nishi for a gift of highly purified A.F.P., Dr A. F. Anderson for access to his patient, Miss Sandra Brown for technical assistance, and Dr C. Gosden, Mr J. Toop, and Miss M. Watt for their help. The research was supported by grants from the Distillers Company Ltd. and the Association for Spina Bifida and Hydrocephalus.
Requests for reprints should be addressed
to
D. J. H. B.
REFERENCES 1. 2. 3. 4.
Brock, D. J. H., Brock, D. J. H.,
5. 6.
Nevin, N. C., Nesbitt, S., Thompson, W. ibid. 1973, i, 1383. Allan, L. D., Ferguson-Smith, M. A., Donald, I., Sweet, E., Gibson A. A. M. ibid. 1973, ii, 522. Seppalä, M., Ruoslahti, E. ibid. 1972, i, 375. Ruoslahti, E., Seppälä, M. Int. J. Cancer, 1971, 8, 374. Brock, D. J. H. Unpublished. Campbell, S., Johnstone, F. D., Holt, E. M., May, P. Lancet, 1972, ii, 1226. Ishiguro, T., Nishimura, T. Am. J. Obstet. Gynec. 1973, 116, 27. Garoff, L., Seppäla, M. J. Obstet. Gynœc. Br. Commonw. 1973, 80, 695. Seppälä, M., Ruoslahti, E. Lancet, 1973, i, 155. Tatarinov, Y. S. Fedn Proc. 1966, 25, 344. Abelev, G. I. Cancer Res. 1968, 28, 1344. Masopust, J., Kithier, K., Radl, J., Koutecky, J., Kotal, L. Int. J. Cancer, 1968, 3, 364. Bourreille, J., Metayer, P., Sauger, F., Matray, F., Fondimare, A. Presse méd. 1970, 78, 1277. Abelev, G. I. Adv. Cancer Res. 1971, 14, 295. Nayak, N. C., Malaviya, A. N., Chawla, V., Chandra, R. K. Lancet, 1972, i, 68. Waldmann, T. A., McIntire, K. R. ibid. 1972, ii, 1112. Seppälä, M., Ruoslahti, E. Br. med. J. 1972, iv, 769.
Sutcliffe, R. G. Lancet, 1972, ii, 197. Scrimgeour, J. B. ibid. p. 1252. Lorber, J., Stewart, C. R., Milford Ward, A. ibid. 1973, i, 1187. Seller, M. J., Campbell, S., Coltart, T. M., Singer, J. D. ibid. 1973, ii, 73.
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
18. 19. 20. 21.
CHILDREN OF ADULT SURVIVORS WITH SPINA BIFIDA CYSTICA KATHLEEN EVANS
C. O. CARTER
Medical Research Council Clinical Genetics Unit, Institute of Child Health, London WC1
Summary
A consecutive series of
patients
with
spina cystica, identified from the records of The Hospital for Sick Children and St. Bartholomew’s Hospital before 1954, have been studied to estimate the risk of neural-tube malformation in the children of such patients who survive to adult life. The 215 survivors who were traced have had between them 104 children, 2 of whom have a neural-tube malformation. Of 100 male survivors, 14 have between them had 35 children, 1 of whom had spina bifida cystica. Of 115 female patients, 38 have between them had 69 children, of whom 1 had anencephaly. The results of this study combined with two other studies give an estimate for risk to offspring of parents of either sex of about 3%. It appears that the risk to children of male patients is at least as high as that of female patients. bifida
Introduction SURVIVORS with spina bifida cystica are now askthe chances of the condition occurring in their children. There is, as yet, little information on which to base an estimate of this risk.
ing about
Tilnte1
reported
on
a
series of 32 adults with
spina bifida cystica on Munster, Germany, 14 of
the genetics register at whom had a total of 24 liveborn and 5 stillborn children. Of the 29 children, 2 had malformations of the central nervous system (C.N.S.), 1 had anencephaly, and 1 had spina bifida cystica (the last 2 cases were both born to the same father). Lorberhas briefly reported on 36 adults with spina bifida, ascertained in various ways, who had a total of 86 children. 2 women and 1 man among the 36 patients had had a child with
spina bifida. The present paper describes a study of a series of 202 survivors of spina bifida cystica who had attended The Hospital for Sick Children, Great Ormond Street, between 1940 and 1953, to discover how many of their children had a C.N.S. malformation. Patients and Methods We examined all available sources of names of patients with spina bifida attending The Hospital for Sick Children between 1940 and 1953. The 10 who had addresses in South Wales were excluded because they will be included in a survey from Cardiff. A total of 576 (253 boys and 323 girls) was found. Of the 576, 305 were known to be dead and a further 22 were presumed dead because the severity of the malformation made their survival most unlikely and their names do not appear on the National Health Service central register; a further 15were known to have emigrated; 4 were in the Armed Forces; 5 in institutions for the mentally retarded; 3 refused to give information; 20, who may still be alive, were not traced. This leaves a total of 202 people on whose offspring we can report.
PRENATAL DIAGNOSIS OF ANENCEPHALY THROUGH MATERNAL SERUM-ALPHAFETOPROTEIN MEASUREMENT D. J. H. BROCK
University Department of Human Genetics, Western General Hospital, Edinburgh EH4 2HU A. E. BOLTON Medical Research Council
Radioimmunoassay Team, Edinburgh
J. M. MONAGHAN Department of Obstetrics and Gynœcology, Western General Hospital, Edinburgh An
anencephalic pregnancy was first diagnosed by measurement of &agr;-feto-
Sum ary
protein (A.F.P.) in maternal serum at 16 weeks and then 21 weeks of gestation. After confirmation of the diagnosis by amniotic-fluid A.F.P. measurement and ultrasonic and X-ray scan, the pregnancy was terminated. It is suggested that maternal serum-A.F.P. levels may be useful in the screening of large numbers of pregnancies for possible central-nervoussystem malformations.
Introduction IN 1972 Brock and Sutcliffe showed that a-fetoprotein (A.F.P.) concentrations in amniotic fluids of anencephalic fetuses were very much higher than in those from normal fetuses 1 Most of their samples obtained between 26 weeks’ gestation and term, amniotic fluid from a 13-week fetus with spina bifida and one from an 18-week anencephalic fetussuggested that diagnosis based on A.F.P. could be made early enough to allow termination of pregnancy. Subsequently, amniotic-fluid A.F.P. levels have been exploited for the interruption of a number of pregnancies leading both to anencephaly 3,4 and to spina bifida.5,6 A.F.P. crosses the placental barrier and can be detected in maternal serum with a sensitive radioimmunoassay.’ We report an early prenatal diagnosis of anencephaly in which the first indication of abnormality was a raised concentration of maternal serum-
were
but
one
A.F.P. 7835
27 October 1973
Case-report The
patient’s
first pregnancy resulted in
a
normal
male, the second in a premature female with congenital heart lesion, and the third in a stillborn anencephalic. of blood was taken weeks. Seruma minor modification of the double-antibody radioimmunoassay described by Ruoslahti and Seppälä,8 using a purified A.F.P. standard supplied by Dr S. Nishi. At 16 weeks the patient’s serum-A.F.p. was 135 ng. per ml. Mean of thirteen control sera between 14 and 18 weeks’ gestation was 38 ng. per ml., with a range of 13-75 ng. per ml. At 21 weeks the patient’s serumA.F.P. was 445 ng. per ml., while a mean of fifteen control sera between 20 and 23 weeks’ gestation was 65 ng. per ml., with a range of 14 to 121 ng. per ml. Amniocentesis was performed, and amniotic-fluid A.F.P. was found by immunoelectrophoresis to be 240 /g. per ml. (upper limit of normal at 21 weeks is 18 Ag. per ml.).9 An ultrasonic scan and X-ray examination confirmed anencephaly, while revealing that the mother had spina bifida occulta. The pregnancy was terminated by highdose oxytocin infusion, and the fetus found to be a male anencephalic without spina bifida.
During the
a
at
again
next pregnancy 16 weeks’ gestation and A.F.P. was determined by
sample
at 21
Discussion
Although anencephaly and spina bifida are relatively common congenital malformations in the U.K., there is no method of identifying most at-risk pregnancies. If the mother has already had an affected child the risk of repetition, calculated empirically, is about 1 in 20. However, more than 90 % of infants with anencephaly and spina bifida will be born to mothers with no family history of central-nervousAmniocentesis on all early system malformation. pregnancies for the purpose of determining amnioticfluid A.F.P. is out of the question. Although ultrasonic investigation has allowed the diagnosis of anencephaly at 17 weeks’ gestation," it is a specialised technique requiring sophisticated interpretation, and is not yet applicable to a large number of patients. The importance of our finding is that it raises the possibility of screening pregnancies through a determination made on a small amount of maternal blood. The values for the patient’s serum-A.F.p., 135 ng. per ml. at 16 weeks and 445 ng. per ml. at 21 weeks, were both substantially above the limited number of controls chosen on the basis that the outcome of
924 pregnancy was known. Ishiguro and Nishimura 11 give an upper limit of normal for 16 weeks of about 50 ng. per ml. and for 21 weeks of about 80 ng. per ml. Garoff and Seppiilii 12 report upper limits for these two gestations of 200 ng. per ml. and 300 ng. per ml., respectively. It is probable that as further samples are obtained our normal ranges will be somewhat widened. It would be unwise to suggest that maternal serumA.F.P. alone could be used to diagnose anencephaly or spina bifida early in pregnancy. It is not clear whether the raised amniotic-fluid A.F.P. found in these conditions will inevitably be reflected in raised maternal serum levels. Seppala and Ruoslahti have reported a case of meningomyelocele where amnioticfluid A.F.P. was considerably increased while the maternal serum level was normal, though this was at 27 weeks of pregnancy.13 Perhaps more common
will be false-positive results, for increased serumis associated with a number of conditions unrelated to pregnancy-in particular, primary hepatocellular carcinomas but also other carcinomas/5-17 and non-malignant diseases of the liver."-21 In pregnancy, a raised A.F.P. has been demonstrated to be associated with threatened abortion,21 nonspecific cases of fetal distress, and intrauterine death, and is anticipated where there is fetomaternal transfusion.l3 Most of the false-positives unrelated to pregnancy will be eliminated by amniotic-fluid A.F.P. measurement. Where both maternal serum and amniotic-fluid A.F.P. are raised, the obstetrician is as well to be alerted, whether the outcome of the pregnancy be a spontaneous abortion, an intrauterine A.F.P.
death,
or an
anencephalic infant.
We thank Dr S. Nishi for a gift of highly purified A.F.P., Dr A. F. Anderson for access to his patient, Miss Sandra Brown for technical assistance, and Dr C. Gosden, Mr J. Toop, and Miss M. Watt for their help. The research was supported by grants from the Distillers Company Ltd. and the Association for Spina Bifida and Hydrocephalus.
Requests for reprints should be addressed
to
D. J. H. B.
REFERENCES 1. 2. 3. 4.
Brock, D. J. H., Brock, D. J. H.,
5. 6.
Nevin, N. C., Nesbitt, S., Thompson, W. ibid. 1973, i, 1383. Allan, L. D., Ferguson-Smith, M. A., Donald, I., Sweet, E., Gibson A. A. M. ibid. 1973, ii, 522. Seppalä, M., Ruoslahti, E. ibid. 1972, i, 375. Ruoslahti, E., Seppälä, M. Int. J. Cancer, 1971, 8, 374. Brock, D. J. H. Unpublished. Campbell, S., Johnstone, F. D., Holt, E. M., May, P. Lancet, 1972, ii, 1226. Ishiguro, T., Nishimura, T. Am. J. Obstet. Gynec. 1973, 116, 27. Garoff, L., Seppäla, M. J. Obstet. Gynœc. Br. Commonw. 1973, 80, 695. Seppälä, M., Ruoslahti, E. Lancet, 1973, i, 155. Tatarinov, Y. S. Fedn Proc. 1966, 25, 344. Abelev, G. I. Cancer Res. 1968, 28, 1344. Masopust, J., Kithier, K., Radl, J., Koutecky, J., Kotal, L. Int. J. Cancer, 1968, 3, 364. Bourreille, J., Metayer, P., Sauger, F., Matray, F., Fondimare, A. Presse méd. 1970, 78, 1277. Abelev, G. I. Adv. Cancer Res. 1971, 14, 295. Nayak, N. C., Malaviya, A. N., Chawla, V., Chandra, R. K. Lancet, 1972, i, 68. Waldmann, T. A., McIntire, K. R. ibid. 1972, ii, 1112. Seppälä, M., Ruoslahti, E. Br. med. J. 1972, iv, 769.
Sutcliffe, R. G. Lancet, 1972, ii, 197. Scrimgeour, J. B. ibid. p. 1252. Lorber, J., Stewart, C. R., Milford Ward, A. ibid. 1973, i, 1187. Seller, M. J., Campbell, S., Coltart, T. M., Singer, J. D. ibid. 1973, ii, 73.
7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
18. 19. 20. 21.
CHILDREN OF ADULT SURVIVORS WITH SPINA BIFIDA CYSTICA KATHLEEN EVANS
C. O. CARTER
Medical Research Council Clinical Genetics Unit, Institute of Child Health, London WC1
Summary
A consecutive series of
patients
with
spina cystica, identified from the records of The Hospital for Sick Children and St. Bartholomew’s Hospital before 1954, have been studied to estimate the risk of neural-tube malformation in the children of such patients who survive to adult life. The 215 survivors who were traced have had between them 104 children, 2 of whom have a neural-tube malformation. Of 100 male survivors, 14 have between them had 35 children, 1 of whom had spina bifida cystica. Of 115 female patients, 38 have between them had 69 children, of whom 1 had anencephaly. The results of this study combined with two other studies give an estimate for risk to offspring of parents of either sex of about 3%. It appears that the risk to children of male patients is at least as high as that of female patients. bifida
Introduction SURVIVORS with spina bifida cystica are now askthe chances of the condition occurring in their children. There is, as yet, little information on which to base an estimate of this risk.
ing about
Tilnte1
reported
on
a
series of 32 adults with
spina bifida cystica on Munster, Germany, 14 of
the genetics register at whom had a total of 24 liveborn and 5 stillborn children. Of the 29 children, 2 had malformations of the central nervous system (C.N.S.), 1 had anencephaly, and 1 had spina bifida cystica (the last 2 cases were both born to the same father). Lorberhas briefly reported on 36 adults with spina bifida, ascertained in various ways, who had a total of 86 children. 2 women and 1 man among the 36 patients had had a child with
spina bifida. The present paper describes a study of a series of 202 survivors of spina bifida cystica who had attended The Hospital for Sick Children, Great Ormond Street, between 1940 and 1953, to discover how many of their children had a C.N.S. malformation. Patients and Methods We examined all available sources of names of patients with spina bifida attending The Hospital for Sick Children between 1940 and 1953. The 10 who had addresses in South Wales were excluded because they will be included in a survey from Cardiff. A total of 576 (253 boys and 323 girls) was found. Of the 576, 305 were known to be dead and a further 22 were presumed dead because the severity of the malformation made their survival most unlikely and their names do not appear on the National Health Service central register; a further 15were known to have emigrated; 4 were in the Armed Forces; 5 in institutions for the mentally retarded; 3 refused to give information; 20, who may still be alive, were not traced. This leaves a total of 202 people on whose offspring we can report.