Neural tube defects in New South Wales, Australia

Cases of spina bifida cystica, encephalocele, and anencephaly occurring over a 9-year period, 1965 to 1973, in New South Wales, Australia, were identified. A low frequency of 1·1 for spina bifida and encephalocele (SB) and 0·9 for anencephaly (A) was found.     

Introduction to P.E. Becker's living history—biography

We present data from the Latin American Collaborative Study of Congenital Malformations (ECLAMC) on prevalence rates and etiologic factor associations in neural tube defects. Two series of data are analyzed: the A series, including 740, 139 consecutive infants born in the 1967–1979 period suitable for secular trend analysis and case-control study of risk factors; and the B series, including 255, 834 consecutive stillborn and liveborn infants of the 1980–1982 period suitable for prevalence rate analysis. Anencephaly was registered in 6.0/10,000 births, spina bifida aperta in 6.2/10,000 births, and cephalocele in 2.4/10,000 births. A stable secular trend was observed for the frequency of all three neural tube defect types. Spina bifida was more frequent in Chile than in the rest of South America. No differences in prevalence rates were seen between tropical and non tropical areas. Parental consanguinity and environmental prenatal factors including maternal illnesses, drug intake, and radiation exposure were found in association with anencephaly and spina bifida.     

Central nervous system abnormalities - contrasting patterns in early and late pregnancy

A total of 509 specimens of spontaneous abortion were studied. Of 364 complete specimens, 15(4.1%) had central nervous system (CNS) abnormalities. The defects which were seen were anencephaly, spina bifida, iniencephaly, encephalocele and anencephaly combined with complete rachischisis. A high proportion (five out of 15) had the more unusual defects of iniencephaly and encephalocele. All except one had ceased development at less than 12 weeks of gestation. Sex chromatin studies showed that males outnumbered females among CNS defective fetuses. When the month of conception was calculated for these abnormal pregnancies, summer and winter peaks were detected. Only one of the 15 patients had a family history of neural tube defect (NTD).
Histological examination of all small fetuses aborted spontaneously revealed two additional facts. First, in fetuses with a localised external CNS defect, the internal abnormality was more extensive. Second, the CNS was also abnormal in some fetuses with no visible external defect.
The proportion of abnormality is much higher than at birth and is also higher than in other surveys of spontaneous abortion.
We suggest that screening for serum alphafetoprotein should be undertaken and amniocentesis considered in pregnancies subsequent to an abortion of this type.     

Congenital malformations associated with anencephaly and iniencephaly.

The necropsy reports of 294 cases of anencephaly and 50 cases of iniencephaly have been examined, and a tubulated list of associated malformations produced. Cases were divided by sex and the presence or absence of spina bifida. Forty-one per cent of the series had other malformations, and other malformations were more common in those cases with spina bifida than in those without. The most frequent single malformations were: hydronephrosis (8%), cleft palate (8%), diaphragmatic hernia (5%), exomphalos (5%), hare lip (4%), and horseshoe kidney (4%). It is suggested that the presence of other malformations in anencephaly or iniencephaly may imply some aetiological heterogeneity.     

Risk factors associated with neural tube defects: exposure during the first trimester of gestation

The neural tube defects (NTD) are a group of malformations of multifactorial etiology. Their high incidence in Mexico and the etiologic heterogeneity observed in several studies, prompted the present investigation with the main objective of looking for risk factors associated to NTD. We analyzed maternal exposure during the first trimester of pregnancy to different environmental factors, such as acute or chronic illnesses, immunizations, smoking, alcoholism, maternal or paternal occupation and exposure to chemicals. The sample include 360 patients with anencephaly, 249 with spina bifida and 44 with encephalocele, ascertained from a total of 230 635 live births and 4,020 stillborns, studied in the Mexican program of Registro y Vigilancia Epidemiológica de Malformaciones Congénitas Externa. Of the risk factors considered, significant differences with the control group were found for anencephaly in relation to maternal viral upper respiratory infection, hyperthermia, ingestion of analgesics, antiemetics and paternal occupation. In the case of spina bifida, significant differences were found only for viral upper respiratory infections.     

Trisomy 13 syndrome and neural tube defects

Abnormalities of the CNS, such as arhinencephaly or holoprosencephaly, are common findings in trisomy 13 syndrome. However, neural tube defects (NTDs) are rarely reported. A review of 267 patients in the literature on reported CNS developmental defects in trisomy 13 syndrome showed only 6 patients with lumbosacral NTDs. No case of encephalocele or anencephaly was found. We report on 3 patients with spina bifida from the records of 34 necropsies of karyotyped trisomy 13 syndrome, which were found among 403,710 births.     

Ethnic differences in the prevalence of anencephaly and sina bifida in Boston, Massachusetts

because of the large Irish population, a group with high prevalence rates of anencephaly and spina bifida, and the small Jewish population, a group with very low prevalences of these anomalies, cases of anencephaly and spina bifida born in 1 of 4 Boston maternity hospitals were compared with a systematic 1 in 300 sample of all births in the same facilities. Estimates of prevalence were made according to ethnic group, socioeconomic status, and parity. As expected, Irish offspring showed high rates (3.1 per 1000 births) of prevalence for these congenital defects, and these rates did not change in degree if the investigation was restricted to mother only, father only, or both parents Irish heritage. If mothers were born in Ireland, however, the prevalence rate was 4.9/1000. Offspring of Jewish mothers had the lowest rates of any ethnic group examined (Protestant, Irish Catholic, Roman Catholic, and other religions), .77/1000. However, in the highest economic classes, differences between the 3 major religions were not significant. Other ancestories showed the following prevalences: Italian, 1.09; Canadian, 3.18; English, 1.49; and other U.S., 2.58. Overall in Massachusetts the rate was 3.11. Prevalence rates increased dramatically with increasing socioeconomic status. Association with parity was also noticed; parity and ehtnic group were independent associations, as were ethnic and socioeconomic class.     

CNS malformations in the kraków region. I. Birth prevalence and seasonal incidence during 1979–1981

The birth prevalence of CNS malformations in the region of Krakow from 1979 to 1981 was determined to be 1.26/1000 from records of all live- and still-birth deliveries. The frequency of anencephaly was 0.23/1,000; spina bifida and encephalocele, 0.70/1000; isolated hydrocephaly, 0.26/1,000; and other CNS anomalies, 0.06/1,000. The observed rates are below the median European level. Female preponderance was found among the probands with anencephaly, encephalomeningocele, and myelomeningocele. Cytogenetic examination of 35 newborns with CNS malformations documented normal karyotypes in all neonates. The analysis of seasonal distribution of proband's birthdate and of date of mother's last menstrual period showed no significant seasonal trend.     

The sex ratio in spina bifida.

Published reports on the sex ratio of spina bifida have been reviewed. With one exception, there seems to be no evidence of variation in the sex ratio of spina bifida. In particular, unlike anencephaly, the sex ratio of spina bifida seems to be unrelated to the prevalence of the malformation: this (M/(M+F)) is of the order of 0.44 in respect of all spina bifida births (liveborn and stillborn). The sex ratio of spina bifida in Negroes does not seem to differ from that in whites (though the data on this point are not numerous). The exception noted above concerns spina bifida occurrring in twins: these cases are disproportionately often female. The point stands in need of explanation.     

Projected number of children with isolated spina bifida or down syndrome in England and Wales by 2020

Children with major congenital anomalies often require lifelong access to health and social care services. Estimating future numbers of affected individuals can aid health and social care planning. This study aimed to estimate the number of children aged 0–15 years living with spina bifida or Down syndrome in England and Wales by 2020. Cases of spina bifida and Down syndrome born during 1998–2013 were identified from the Northern Congenital Abnormality Survey and the National Down Syndrome Cytogenetic Register, respectively. The number of infants born with spina bifida during 1998–2019 were estimated by applying the average prevalence rate in the North of England to actual and projected births in England and Wales. Poisson regression was performed to estimate the number of infants born with Down syndrome in England and Wales during 1998–2013 and 2004–2019. The numbers of children aged 0–15 living with spina bifida or Down syndrome in 2014 and in 2020 were then estimated by multiplying year- and age-specific survival estimates by the number of affected births. An estimated 956 children with isolated spina bifida, 623 children with spina bifida and hydrocephalus and 11,592 children with Down syndrome aged 0–15 years will be living in England and Wales by 2020, increases of 7.2%, 12.0% and 12.7% since 2014, respectively. Due to improvements in survival, an increase in population size and changes in maternal age distribution at delivery, we anticipate further increases in the number of children living with spina bifida or Down syndrome by 2020.     

基于人群监测和医院监测的高发地区出生缺陷流行病学特征比较

目的比较中国出生缺陷高发地区人群监测和医院监测出生缺陷流行病学特征的差异。方法在中国出生缺陷高发的山西省选择2个高发县作为研究地区,对该地区2002年1月1日至2004年12月31日孕满20周及以上胎儿及婴幼儿出生缺陷的发生水平进行分析。人群监测采用社区调查和医院登记相结合的方法,医院监测来自当地医院妇产科及B超检查的登记册,比较两种监测方法出生缺陷发生率及顺位,孕20周至生后7d或至3岁时的差异。结果 2002至2004年医院监测累积出生4855人,出生缺陷113例,出生缺陷发生率为232.7/万出生;人群监测累积出生6420人,出生缺陷223例,出生缺陷发生率为347.4/万出生,差异有显著统计学意义（P〈0.001）。在孕20周至生后7d的常规监测年龄段,医院和人群监测资料出生缺陷均以神经系统畸形为主,神经系统、耳部畸形、泌尿生殖系统以及皮肤缺陷发生率均为人群监测高于医院监测。人群与医院监测的前5位出生缺陷顺位一致,依次为无脑儿、脊柱裂、先天性脑积水、脑膨出、唇和（或）腭裂。当人群监测年龄延长至3岁时,出生缺陷发生率高达844.2/万出生,是孕20周至生后7d人群监测数据的2.43倍,是医院监测数据的3.63倍。人群监测孕20周至3岁时出生缺陷顺位变化较大,前5位依次为腹股沟疝、无脑畸形、先天性智力低下、先天性心脏病和脊柱裂。结论出生缺陷的水平和顺位与监测方法和时段密切相关,在常规人群出生缺陷监测基础上,可将部分出生缺陷监测时间延长至3岁,可发现更多常规监测以外的出生缺陷种类,为出生缺陷预防提供可靠依据。     

Possible X-linked anencephaly and spina bifida—report of a kindred

Causal heterogeneity of anencephaly and spina bifida has been demonstrated; in rare families the neural tube defect may be caused by a single gene. We report a family in which four cases of anencephaly or spina bifida may represent X-linked inheritance.     

Epidemiological study of anencephaly in Italy and anatomo-pathological findings in cases observed by us

Epidemiologic study of anencephaly in Italy and anatomo-pathological analysis of our series. Out of about 1,000,000 new-borns enrolled in the IPIMC Register (Italian Multicenter Study on Congenital Malformations) from 1978 to 1986, 205 were found with isolated anencephaly and 59 with anencephaly associated with other independent malformations, for a total of 284 cases. The study of preferentially associated malformations has pointed out that anencephaly is mainly associated with three kinds of malformations: cleft lip and/or palate, ambiguous genitalia, gastroschisis. Yet these combinations did not result to be the most common with spina bifida, thus proving the heterogeneity of these two neural canal defects. The total rate is 2.7 (/10,000), higher in the South (3.2) than in the North (2.3). The highest rate was reported in Sardinia (6.0). Moreover, a 58.1% trend reduction between 1978-80 and 1984-86 with seasonal peak in January (3.6%) was reported. The following major new-born and mother characteristics have been studied: sex (M/F = 0.76), twin pregnancies (6.4%), vitality (live births: 60, from them 40 died in the same day, 16 between day 1 and 7, 4 after day 7 since birth; still births: 47; born with unknown vitality: 10), mother age (no influence), consanguinity (4.4%), average weight (1,891 gr.), mean gestational age (246 days), intrauterine growth retardation (52.9%). The importance of a proper and careful examination during autopsy is stressed to identify and describe possible associated malformations. Immunohistochemical data (4 cases) on the cerebro-vascular area are reported, mainly to identify any neural buds and related structures (glia, neurofilaments, ganglia, nerves, ependyma, choroid plexus) as well as the connection between osteocartilaginous and epithelial and/or vascular rudiments.     

Associated malformations among infants with neural tube defects

Infants with neural tube defects (NTDs) often have associated congenital anomalies. The reported frequency and types of associated malformations vary between different studies. The purpose of this investigation was to assess the frequency and types of associated malformations among infants with NTDs in a geographically well-defined population from 1979 to 2008 of 402,532 consecutive births. Of the 441 infants with NTDs born during this period, 20.4% had associated malformations. Infants with associated malformations were divided into those with recognizable conditions [11 (2.5%) infants with chromosomal and 23 (5.2%) with non-chromosomal conditions], and those without recognizable conditions [56 (12.7%) infants with multiple malformations]. Associated malformations were more frequent among infants with encephalocele (36.8%) than those with anencephaly (11.5%) or spina bifida (23.8%). Oral clefts and malformations in the musculoskeletal, renal and cardiovascular systems were the most commonly observed associated anomalies. The frequency of associated malformations in infants with NTDs emphasizes the need for a thorough investigation of these infants. Routine screening for other malformations, especially facial clefts and musculoskeletal, renal and cardiac anomalies, may need to be considered in infants with NTDs, and referral of these infants for genetics evaluation and counseling seems warranted.     

Differences between the events preceding spina bifida and anencephaly.

It is usually held that there is a time continuum in the formation of monoxygotic (MZ) twins which is indexed by their placentation, running from dichorionic to monochorionic diamniotic to monochorionic monoamniotic and conjoined pairs. There is good evidence that this continuum is characterised by a continuum of predisposition to anencephaly, slightly raised in dichorionic pairs but very high in some sorts of conjoined pairs. Although MZ twins, especially monoamniotic and conjoined pairs, are peculiarly liable to anencephaly, they are not particularly susceptible to spina bifida. Among twin pairs concordant for anencephaly or spina bifida, there are strikingly few concordant in the sense of one twin having anencephaly and the other spina bifida, in contrast with the numbers of pairs concordant for the same malformation. The prevalence of anencephaly in double monsters varies with the type of monster, being high in diprosopus. These findings may be explained by the timing of embryonic events.     

胎儿神经系统畸形超声产前诊断分析

目的探讨胎儿神经系统畸形的超声诊断价值及临床意义。方法回顾性分析86例超声产前诊断的胎儿神经系统畸形病例的声像图特征与临床意义。结果超声产前诊断胎儿神经系统畸形86例,其中脑积水23例,无脑或露脑畸形21例,脊柱裂15例,脑或脑膜膨出8例,前脑无裂畸形7例,Dandy-Wallker畸形6例,胼胝体发育不全3例,蛛网膜囊肿2例,Galen静脉瘤1例,合并多发畸形44例,86例均经引产或出生后证实,诊断符合率100%,合并多发畸形并发畸形漏诊9例,并发症漏诊率10.47%。结论超声对产前胎儿神经系统畸形的诊断具有重要的临床价值。     

A targeted sequencing panel identifies rare damaging variants in multiple genes in the cranial neural tube defect,anencephaly

Neural tube defects (NTDs) affecting the brain (anencephaly) are lethal before or at birth, whereas lower spinal defects (spina bifida) may lead to lifelong neurological handicap. Collectively, NTDs rank among the most common birth defects worldwide. This study focuses on anencephaly, which despite having a similar frequency to spina bifida and being the most common type of NTD observed in mouse models, has had more limited inclusion in genetic studies. A genetic influence is strongly implicated in determining risk of NTDs and a molecular diagnosis is of fundamental importance to families both in terms of understanding the origin of the condition and for managing future pregnancies. Here we used a custom panel of 191 NTD candidate genes to screen 90 patients with cranial NTDs (n = 85 anencephaly and n = 5 craniorachischisis) with a targeted exome sequencing platform. After filtering and comparing to our in‐house control exome database (N = 509), we identified 397 rare variants (minor allele frequency, MAF < 1%), 21 of which were previously unreported and predicted damaging. This included 1 frameshift (PDGFRA), 2 stop‐gained (MAT1A; NOS2) and 18 missense variations. Together with evidence for oligogenic inheritance, this study provides new information on the possible genetic causation of anencephaly.     

Congenital absence of gluteal muscles Report of two sibs

A family is described with the following features: 1) Two propositi, a male and a female, with congenital absence of gluteal muscles and with spina bifida occulta. 2) Both parents and two apparently normal siblings with sacral spina bifida occulta. 3) Two siblings of the propositi who died soon after birth, one with anencephaly and the other with a probable spina bifida.
Two alternative hypotheses for the etiology of these malformations are suggested: first, the muscular defect could be caused by an autosomal recessive gene independent of the open neural-tube defects; second, both types of malformations could be due to the same autosomal recessive gene. Then compensatory muscular changes which allow the propositi to walk are discussed.     

Reduction of birth prevalence rates of neural tube defects after folic acid fortification in Chile

To verify whether the decreasing neural tube defects birth prevalence rates in Chile are due to folic acid fortification or to pre-existing decreasing trends, we performed a population survey using a network of Estudio Colaborativo Latino Americano de Malformaciones Congenitas (ECLAMC, Latin American Collaborative Study of Congenital Malformations) maternity hospitals in Chile, between the years 1982 and 2002. Within each maternity hospital, birth prevalence rates of spina bifida and anencephaly were calculated from two pre-fortification periods (1982-1989 and 1990-2000), and from one fortified period (2001-2002). There was no historical trend for spina bifida birth prevalence rates before folic acid fortification, and there was a 51% (minimum 27%, maximum 66%) decrease in the birth prevalence rates of this anomaly in the fortified period. The relative risks of spina bifida were homogeneous among hospitals in the two period comparisons. There was no historical trend for the birth prevalence of anencephaly comparing the two pre-fortified periods, but the relative risks were heterogeneous among hospitals in this comparison. There was a 42% (minimum 10%, maximum 63%) decrease in the birth prevalence rate of anencephaly in the fortified period as compared with the immediately pre-fortified period, with homogeneous relative risks among hospitals. Within the methodological constraints of this study we conclude that the birth prevalence rates for both spina bifida and anencephaly decreased as a result of folic acid fortification, without interference of decreasing secular trends.     

Upper and lower neural tube defects: an alternate hypothesis.

It has been suggested that neural tube defects (NTDs) of the upper type (anencephaly, encephalocele, and thoracic spina bifida) may have a pathogenesis different from those of the lower type (lumbosacral spina bifida), since recurrent cases within a sibship were said always to be concordant with respect to NTD type. Also, spontaneous abortion, additional malformation, and recurrence rate were observed to be higher in the upper group, and there was an excess of females in upper NTD probands. To test this hypothesis, we measured the above variables in upper and lower NTDs in a sample from Quebec. We found less than full concordance (50%) of NTD type in 18 sib pairs. Recurrence rate was not significantly lower in the lower NTD group (5.6 v 5.8%). The other variables were in general agreement with previous studies, inconsistent findings possibly attributable to different NTD population incidences. These findings can be accounted for if upper and lower NTDs share a similar pathogenesis and the embryo is more susceptible during early than late neural tube formation.