Birth defects monitoring in underdeveloped countries: an example from Uruguay

Medical authorities in developing countries are primarily interested in nutritional and infectious diseases. Therefore, activities directed to the prevention and control of low priority illnesses, such as birth defects, need to be particularly effective, simple, and economical. Monitoring of congenital anomalies is one of the preventive activities which can be efficiently performed at very low cost. Guidelines for this are given, and their application exemplified by the case of Uruguay. Uruguay has recently attained an infant mortality rate of 20/1,000, with the congenital anomalies ranking as its second cause. The government of Uruguay, through the Pan American Health Organisation/World Health Organisation (PARO/WHO) called the Estudio Colaborativo Latino Americano de Malformaciones Congenitas (ECLAMC) for advice in order to plan a program for the prevention of birth defects. The recommendations given were based on conclusions drawn from the analysis of data the ECLAMC program has been accumulating, from Uruguay and other Latin-American countries, since 1967. The case of Uruguay clearly indicates that sensible guidelines for birth defects prevention can be provided, after working with this "low priority and uninteresting" group of illnesses for more than twenty years.

EL BUSCA and the value of signals in the diagnosis of dysmorphic syndromes: good and bad handles in computer assisted differential diagnosis

A computer system for the assistance of syndrome diagnosis in dysmorphology (EL BUSCA) was developed, and used to test the mechanics of the diagnostic process. EL BUSCA has a reference file (REF) with 200 syndromes, expressed in 175 signals. Signals have a weight value resulting from the difference between the number of syndromes including that sign and the total number of syndromes in the REF. A mean signal weight was calculated for each syndrome. The system was tested with 200 published cases (CASES), representing 82 different syndromes. Each consultation (CONS) entered up to 15 patient signals. The system then selected syndromes having three or more of those signals. 'Present' (REF+CASE), 'Absent' (REF only), and 'Additional' (CASE only) signals, as well as the score given by the sum of the weights of 'present' signals, were displayed for each suggested diagnosis. A consultation was successful (positive answer) if the correct diagnosis appeared among the first 12 ranked. EL BUSCA gave a positive answer in 82% of the 200 test consultations. Linear regression, with ranking of the correct diagnosis among the answers as the dependent variable, was used for the analysis of the following results. For the REF, no relationship was found for either the number or the mean weight of the signals with the ranking of the correct diagnosis. For the CASES, there was a linear relationship between the number of signals of each consultation and the ranking of the correct diagnosis, indicating that the larger the number of signals consulted, the lower the ranking of the correct diagnosis. No effect was seen for the mean weight of consulted signals.(ABSTRACT TRUNCATED AT 250 WORDS)

Monthly and seasonal variations in the frequency of congenital anomalies

Three large and comparable series of births were used to test the working hypothesis that if there is a real seasonal variation in the frequency of a given congenital malformation; it would have to be shown by adequate analysis; to be more overt in non-tropical areas; and to be six months out of phase in northern and southern hemispheres. The data set were hospital births from tropical (287,165 births) and non-tropical (582,585 births) South America, and from Italy (508,536 births). Sixteen well-defined malformation types were tested: anencephaly, spina bifida, cephalocoele, hydrocephaly, microtia, cleft palate, cleft lip, oesophageal atresia, anal atresia, hypospadias, pes equino-varus, pes talovalgus, postaxial polydactylyl, pre-axial polydactylyl, diaphragmatic hernia, and Down's syndrome. No seasonal variation was proven (p less than 0.01) for any malformation type in any of the three series of data by means of Walter and Elwood's test, or Hewitt et al's non-parametric test2 applied to seven instances with sample sizes smaller than 50 cases. Variations of borderline significance (p less than 0.05) included oesophageal atresia in tropical South America, none in non-tropical South America, and anencephaly in Italy. It is concluded that seasonal variation in the occurrence of congenital malformations is a rare phenomenon when tests are strictly used within their recommended limitations.

Anticonvulsant drugs and malformations is there a drug specificity?

The distribution of anticonvulsant drug therapy was studied in 318 malformed infants with known histories of maternal epilepsy. Data on the infants was collected from six birth defect monitoring programs in Europe and South America. Use of specific types of anticonvulsants varies widely among reporting countries. Heterogeneity of drug-malformation distribution, was analyzed to determine whether use of specific drugs were linked to specific malformations. A significant association was seen between maternal use of valproic acid and spina bifida, and a weaker, non-significant one between carbamazepine and spina bifida. Facial clefts were associated with both diphenylhydantoin and phenobarbitone use and also with polytherapy. These differences indicate that the actual drug used is significant for the teratogenic process. The technique may be useful in analysis of other drug-related teratogenic questions.

Acrocallosal syndrome in a girl born to consanguineous parents

The present report describes on a 1-year-old girl with macrocephaly, bulging forehead, ocular hypertelorism, antimongoloid palpebral slant, convergent strabismus, atrophy of optic papillae, short philtrum, protruding lips, high-arched palate, bifid uvula, broad trunk, apparently widely spaced nipples, diastasis recti, small umbilical hernia, tapering fingers, fifth-finger clinodactyly, postaxial polydactyly of the left hand, and bilateral hallux duplication. Partial agenesis of the corpus callosum and central diffuse cortical cerebral atrophy was documented on computed tomography. Chromosomes were normal. Parents were related as half first cousins. Their previous pregnancy had ended in a miscarriage. We suggest that this patient has an acrocallosal syndrome inherited as an autosomal recessive trait. This supports other recent reports that have considered this entity to differ from Greig cephalopolysyndactyly.

The epidemiology of conjoined twins in Latin America

Twenty-three cases of symmetrical conjoined twins were registered by the Latin-American Collaborative Study of Congenital Malformations (ECLAMC) in 1,714,952 births, which were observed during the 1967-1986 period in 95 maternity hospitals distributed in eleven Latin-American countries. This results in a birth prevalence rate of about 1/75,000 births. The secular and geographic distribution of this material do not depart from random in spite of one hospital with three cases, and two hospitals with two cases each, within a short time period. These 23 cases include one diprosopus, 3 dicephalus, one ischiopagus, 5 pygopagus, none dipygus, 3 syncephalus, none craniopagus, 9 thoracopagus, one omphalopagus, and one rachipagus. Sex distribution is even, with 12 male and 11 female cases.

Epidemiology of ambiguous genitalia in South America

We present descriptive epidemiologic data on ambiguous genitalia (AG), obtained in the period 1967-1982 by the Latin American Collaborative Study of Congenital Malformations (ECLAMC) through 70 participating hospitals located in 34 cities of 9 South American countries. The observed prevalence rate for isolated AG was about 1/20,000 births, with at least 1/4 and probably as much as 1/2 due to congenital adrenal hyperplasia. When AG cases associated with other congenital anomalies were also considered, the overall frequency of AG was 1/6,900 total births (1/10,000 for live and 1/350 for stillbirths). The prevalence rates were homogeneously distributed among the different countries, and there was a stable secular trend. AG was more frequent in nontropical than in tropical areas of South America, and there was a significant seasonal variation with its acrophase in August (winter). A case-control analysis of 14 risk factors showed an association of AG with a prenatal history of acute maternal illnesses. These data do not support an etiological relationship between AG and hypospadias.

Prevalence rates of microtia in South America

A high frequency of microtia in Quito (Ecuador) was detected by the Latin American Collaborative Study of Congenital Malformations (ECLAMC), and the data available on file were used to define the cluster and to test some potential risk factors. The Quito material consisted of 46 041 livebirths from two hospitals. The rest of the sample consisted of 553 068 livebirths from 58 hospitals located in 24 cities of six other South American countries. The observed prevalence rate for microtia was over five times higher in Quito (17.4/10 000) than in the other cities (3.2/10 000). The microtias from Quito were mostly represented by isolated forms (without other anomalies except for preauricular tags and/or sinuses), and the proportion of severe microtia was higher than in the rest of the sample. Neither seasonal, nor secular variations were observed in Quito or the rest of the sample; data suggesting the geographical cluster did not arise in recent years. Case-control analysis of familial, prenatal and perinatal history data in 184 cases with isolated microtia (68 from Quito and 116 from the rest) and in 184 matched non-malformed control newborn babies, identified prenatal drug exposure, high birth order, and elevated paternal age as risk factors for the microtias born in Quito.

The birth prevalence rates for the skeletal dysplasias

This study was undertaken to establish the prevalence rates at birth of the skeletal dysplasias that can be recognised in the perinatal period. Using the data base of the Latin-American Collaborative Study of Congenital Malformations (ECLAMC), for the years 1978 to 1983, on 349 470 births (live and stillbirths), a crude prevalence rate of 2.3/10 000 was observed. However, several indications of under-registration suggest that the real value is about twice that observed. The most frequent types of skeletal dysplasia were achondroplasia, with a prevalence rate between 0.5 and 1.5/10 000 births, the thanatophoric dysplasia/achondrogenesis group (0.2 and 0.5/10 000 births), and osteogenesis imperfecta (0.4/10 000 births). The mutation rate for autosomal dominant achondroplasia was estimated at between 1.72 and 5.57 X 10(-5) per gamete per generation.

Epidemiology of neural tube defects in South America

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, A 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.

On monitoring the multiply malformed infant. I: Case-finding, case-recording, and data handling in a Latin American program

The methods used by the Latin American Collaborative Study of Congenital Malformations (ECLAMC) for monitoring the birth prevalence of multiply malformed infants are based on a clinical-epidemiological approach oriented to the early detection of teratogenic agents. They consist of three steps: 1) the analysis of observed vs expected rates of all congenital anomalies (CA), including their isolated and associated forms; 2) the same type of analysis applied to each multiple congenital anomaly (MCA) pattern; and 3) a clinical case presentation reserved only for those considered as true MCA because of presence of three or more independent CA. During the period 1982-1983 299,231 infants were examined. Multiply malformed infants, excluding Down syndrome cases, were born at a rate of 4/10,000, 40% having syndromes (two or more interrelated CA), 30% anomaly pairs, ie, two independent CA, and 30% true MCA cases. In a program with 150,000 births per year, as in ECLAMC, this means about five true MCA cases per week, a number easily handled individually on a clinical basis.

Inbreeding in a South-American newborn series

Parental consanguinity was investigated in a series of 16, 137 non-malformed newborn infants, ascertained in 64 hospitals, of 27 cities, in seven South-American countries. Parental consanguinity was detected in 135 (0.84%) newborns, giving a mean inbreeding coefficient (a) of 0.00053. The subsamples for five of the seven countries (Brazil, Chile, Ecuador, Uruguay, Venezuela) showed similar consanguinity rates, of about one per cent, an a ranging from 0.00040 to 0.00070, approximately. One country, Argentina, had a three times lower value for both indicators: consanguinity rate: 0.3%, a: 0.00011. Another country, Peru, could not be individually analyzed because of its small sample size. Considering the whole South-American sample, first cousin represented 60% of all consanguineous matings. Significantly more female than male intermediate ancestors were counted in the specified total of consanguineous matings, suggesting a preferential consanguineous mating pattern for urban South-American populations.

Epidemiology of congenital pigmented naevi: II. Risk factors

Genetic and environmental risks factors were investigated in a sample of 989 non-malformed newborn infants with skin pigmented naevi (PN), and in 989 non-malformed non-PN, control babies. The samples were obtained from a population of 531,831 livebirths, from fifty-nine South-American maternity hospitals. No significant differences were observed between the PN and control groups for the following risk factors: sex, twinning, parental consanguinity, socioeconomic level, parental ages, birth order, fetal presentation, type of delivery, postnatal mortality, and first trimester of pregnancy histories for maternal chronic illnesses or immunizations, radiation exposure, drug intake, and vaginal bleeding. PN infants were associated with high frequencies of Black racial ancestry, positive prenatal history for maternal acute illnesses, and high mean values for length of gestation and birth weight. The observed association of PN with maternal acute illnesses could be a spurious one, due to partial dependence upon Black racial ancestry, and to maternal memory bias. The analysis of the intrauterine growth curves showed that PN infants have a low prematurity rate, and a high mean by the control newborn group. This observation suggest that congenital PN appear in the latest stages of intrauterine development. No evidence was obtained to allow us to consider congenital PN as true developmental anomalies.

Hypospadias: an epidemiological study in Latin America

Epidemiological variables in relation to hypospadias were analyzed in a case-control study of a liveborn population from six Latin American countries. the frequency of hypospadias was 7.6 per 10,000 livebirths (324/423,839). The cases were divided into three types: distal (72%), proximal (18.5%) and non-specified cases (9.5%). The control group consisted of the first nonmalformed child born after each of the patients and was matched by sex, place, and time of birth. Other coexisting malformations were found in 13.6% of cases. The Brazilian sample showed the highest incidence rate (17.7/10,00) and also the highest incidence of severe forms (5.0/10,000) as compared with the other countries. a circannual rhythm was detected using several different statistical procedures. Low mean birth weight, twinning, vaginal bleeding, and drug exposure during the 1st trimester (particularly sex hormones) were found to be risk factors. The more severe forms had a higher neonatal mortality rate and higher inbreeding when compared with the controls or milder forms. The heritability coefficient was 0.6772 +/- 0.0675. The possible role of maternal sex hormone intake and disturbances of human chorionic gonadotropin during the first trimester are discussed.

Syndactyly: frequency of specific types

Syndactyly without other combined limb anomalies, Poland complex, or amniotic bands, was diagnosed in 174 of 599, 109 consecutive newborn infants (3/10,000). Syndactyly was the only diagnosed anomaly in 133 cases, and it was associated with other anomalies in 41. The most common type of syndactyly was isolated syndactyly of the second and third toes (70 cases), which affected more males than females, and had a higher than expected frequency of white non-Latin-European ancestry. The second most frequent type was isolated syndactyly of the middle and ring fingers (18 cases), and the third was isolated syndactyly of the fourth and fifth toes (13 cases). Considering both isolated and syndromal cases, 66% (114/172) could be assigned to one or another of the fourth genetic categories of syndactyly described by Temtamy and McKusick [1978]. This, plus the high frequency of affected first degree relatives observed (25/434:6%), suggests that the genetic forms of syndactyly may be more common than might be suspected from the small number of pedigrees in the literature.

Pectoralis major muscle defect and Poland complex

Pectoralis major muscle defect (PMD) was diagnosed in 27 infants from a series of 599,109 live births in South America (1/22,189). In all 27 cases the PMD was unilateral, mainly affecting the right side (20/27), and there were more male (19/27) than female cases. No familial cases and no parental consanguinity were recorded. A positive correlation was observed between PMD and sex hormone intake and vaginal bleeding in the first trimester of pregnancy. In 12 (1/49,925) of the 27 PMD cases hypoplasia and/or syndactyly of the ipsilateral hand was also diagnosed. The index-middle interdigital space was affected in all 11 cases with symbrachydactyly. Additional congenital anomalies were observed in 4/27 cases, and they were: hemangiomas, hypospadias, and clubfeet. Poland complex (12 cases), isolated PMD (15 cases), and isolated symbrachydactyly (18 cases), showed a similar pattern for symmetry, sidedness, syndactyly type, and sex ratio.

Patterns of combined limb malformations

Seven different limb malformations types were defined in 544 affected newborns, apparently free from other anomalies, obtained from a series of 297,299 livebirths. These seven malformation types were: polydactyly, limb reduction, brachydactyly, symphalangy, syndactyly and split hand/foot. One anomaly type was present in 472 newborns (1.58/1,000) and two or three in 72 (0.24/1,000). The observed combinations of two or three limb malformation types cannot be explained as chance association. Therefore, a common etiopathogenic mechanism has to be considered when two or more limb malformation types are combined in a given individual. The most frequent observed combinations were: reduction-brachydactyly, reduction-syndactyly, brachydactyly-syndactyly, polydactyly-syndactyly, and reduction-brachydactyly-syndactyly. Based on affected limb distribution, sex ratio, and familial recurrence rates, it is suggest that a reduction anomaly is the primary component in all tested combinations while syndactyly tends to be a secondary one when combined with any other limb anomaly type.

Descriptive system for congenital limb anomalies

A descriptive system for the nomenclature, notation and classification of congenital limb malformations, suitable for clinical, epidemiological and experimental use is presented. Every developmental limb anomaly is described by stating the type of anomaly and the affected anatomic structure. All anomalies are classified into three basic types: excess, deficiency and fusion. The anatomic structure of the affected limb is defined within a two dimensional order. This system was used to describe 652 cases with isolated developmental limb anomalies obtained from two series of observations. The observed data are presented in a progressively expanded classification ranging from 4 to 497 diagnostic categories. Observed incidence rates for the four main types of anomaly from a sample of 297,299 consecutive livebirths, are: excess: 1.22; deficiency: 0.17; fusion: 0.20; combined: 0.24 per thousand.

Neonatal testicular torsion in two brothers

Two brothers presenting neonatal testicular torsion are reported. The findings suggest an autosomal or X-linked recessive pattern of inheritance for the anatomical underlying anomaly.