Biomedical subjects
Publications and source records attributed to M C Cornel.
In a family with two cystic fibrosis (CF) patients and consanguineous parents, DNA analysis showed that the CF in the children was not caused by homozygosity by descent, since two different mutations were involved. A formula is given for calculating the probability that parental consanguinity, if it exists, is causally related to the existence of an autosomal recessive disease in affected children.
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Down syndrome is caused by presence in triplicate of (a part of) chromosome 21, usually on the basis of a standard trisomy-21. The risk of a child's having a standard trisomy-21 depends on the mother's age. On the basis of the maternal age distribution and age-specific risks, the expected number of neonates with Down syndrome born in 1981-1986 in the EUROCAT region North-East Netherlands is calculated. The number of neonates with Down syndrome registered with EUROCAT does not differ to a statistically significant extent from the expected number. The influence of the rising age-specific fertility in women over 28 years of age and the effect of the moving-up of the increasingly large birth cohorts 1945-1965 are discussed. If the uptake rate for prenatal cytogenetic diagnosis remains constant, these factors will in the next few years lead to an increase of the prevalence of Down syndrome among full-term infants.
Several authors have reported a possible association between IVF or induction of ovulation on the one hand and the occurrence of neural tube defects on the other hand. Here a review is given of recent literature on this subject, including data available from The Netherlands. Collaborative epidemiologic studies are needed to evaluate the potential risks. In individual pregnancies prenatal examination is advised. In spontaneous abortions fetal pathological evaluation is desirable.
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Child bearing at an early age and prenatal cytogenetic diagnosis in pregnant women of advanced age, combined with selective abortion, make it possible to avoid the birth of many children with serious chromosomal anomalies. To see how many of such births were still avoidable in Europe, data from 16 regional EUROCAT registers of congenital anomalies in nine EEC countries were analysed. In the period 1979-1982 about 30% of children with unbalanced anomalies of autosomes were born (live- and still-births) to mothers over 35 years of age. This amounts to an estimated 1300 cases yearly in the entire population of the nine countries. The approach shows the possible use of registry data for monitoring effects of avoidance strategies.
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Randomized controlled trials have proven that periconceptional folic acid intake reduces the risk of neural tube defects (NTDs). This lead to different public health policies: fortification of foods in many countries and supplementation in some others. We concentrate here on pro's and con's of fortification policies. Meanwhile, new beneficial but also potential adverse effects are being hypothesized. Highest level evidence is available for the protective effect of folic acid on NTDs. Lower level evidence suggests other protective effects, but also some potential adverse effects, such as masking Vitamin B-12 deficiency, increasing twinning rates and an 'acceleration phenomenon' in pre-existing malignant neoplasms. While observational studies show lower cancer rates associated with increased folate intake, some case reports and animal experiments suggest opposite effects. Thus, public health policy makers are facing the question of balancing beneficial and potential adverse effects repeatedly. We propose that the scientific debate no longer focuses on NTDs alone, but that a comprehensive evaluation be undertaken by a public health authority with experience in complex meta-analyses and technology assessment.
In humans, unpaired organs are placed in a highly ordered pattern along the left-right axis. As indicated by animal studies, a cascade of signaling molecules establish left-right asymmetry in the developing embryo. Some of the same genes are involved also in limb patterning. To provide a better insight into the connection between these processes in humans, we analysed the symmetry of limb deficiencies among infants with multiple congenital anomalies. The study was based on data collected by the International Clearinghouse for Birth Defects Monitoring Systems (ICBDMS). Registries of the ICBDMS provided information on infants who, in addition to a limb deficiency, also had at least one major congenital anomaly in other organ systems. We reviewed 815 such cases of which 149 cases (18.3 %) were syndromic and 666 (81.7 %) were nonsyndromic. The comparisons were made within the associated limb deficiencies, considering the information on symmetry, using a comparison group with malformations associated not involved in the index association. Among the non-syndromic cases, the left-right distribution of limb deficiencies did not differ appreciably between limb deficiency subtypes (e.g., preaxial, transverse, longitudinal). The left-right distribution of limb anomalies did not differ among most types of non-limb anomalies, though a predominance of left-sided limb deficiencies was observed in the presence of severe genital defects - odds ratio [OR], 2.6; 95 % CI, 1.1-6.4). Limb deficiencies (LDs) were more often unilateral than bilateral when accompanied by gastroschisis (OR, 0.1) or axial skeletal defects (OR, 0.5). On the contrary, LDs were more often bilateral than unilateral when associated with cleft lip with or without cleft palate (OR, 3.9) or micrognathia (OR, 2.6). Specifically, we found an association between bilateral preaxial deficiencies and cleft lip, bilateral amelia with gastroschisis and urinary tract anomalies, and bilateral transverse deficiencies and gastroschisis and axial skeleton defects. Of 149 syndromic cases, 62 (41.6 %) were diagnosed as trisomy 18. Out of the 30 cases of trisomy 18 with known laterality, 20 cases were bilateral. In the remainder the right and left sides were equally affected. Also, in most cases (74.4 %) only the upper limbs were involved. In conclusion the left-right distribution of limb deficiencies among some non-limb anomalies may suggest a relationship between the development of the limb and the left-right axis of the embryo.
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Cleft lip with or without cleft palate [CL(P)] has a high prevalence [corrected] in the northern Netherlands. Several epidemiological parameters for oral clefts, including both CL(P) and cleft palate (CP), were analysed and compared with the literature. Except for the high prevalence at birth of isolated CL(P) no major differences in the pattern of occurrence described elsewhere were found. So far, descriptive epidemiological studies have not given any insight into the aetiology of this high CL(P) prevalence [corrected] in the Northern Netherlands. Therefore, case control studies on possible risk factors have been initiated.