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We report a familial deletion of (8q) detected in amniocytes of a fetus with a normal ultrasound and in the phenotypically normal mother, who has now had three pregnancy losses. Chromosome analysis of amniocytes and maternal peripheral blood cells showed an interstitial deletion of (8)(q24.13q24.22), which is distal to the region associated with Langer-Giedion syndrome (LGS) or trichorhinophalangeal (TRP) syndrome. This deletion was confirmed by fluorescence in situ hybridization with a c-myc cosmid clone and chromosome 8 painting library.

Chimerism in humans is usually found only because of discrepancies in unique blood group typing or sex chromosome complements. We describe a case found because of an inherited chromosomal translocation. A female carrier of the balanced reciprocal translocation t(14;20)(q31;q13.3) had a twin pregnancy. After birth the B-twin, a girl, was found to have the balanced translocation. The A-twin, a severely malformed and stillborn boy, had two different karyotypes; a normal 46,XY and an unbalanced translocation derivative 46,XY,-14, +der(14)t(14;20)(q31;q13.3). He was a dispermic chimera, formed by two fertilized oocytes.

Four sibs with varying degrees of caudal dysgenesis are described. Case 1 showed aberrant umbilical cord vasculature with a single umbilical artery near the placental insertion. Cases 2 and 3 showed full sirenomelia, one with a complex congenital heart defect. Case 4 had an imperforate anus and an excessively long umbilical cord. The father's half-sib had an imperforate anus, rectovaginal fistula and genitourinary anomalies. A dominant gene with reduced penetrance is likely.

Reproductive fitness of carriers of heterochromatic variants of the human karyotype was found to be normal. The method was based on a comparison between known carriers and known non-carriers from the same pedigree in respect of live births, generation time and survival of offspring to reproductive age. A subset of the data had been included in an earlier study in which reproductive fitness of carriers was found to be significantly reduced. Our analysis suggests that the result may have been fortuitous, since it was not supported by the additional data. There was no evidence of heterogeneity between carriers of different types of variant or of different sex. There were indications of increased fetal losses to carriers, but the number of spontaneous abortions was insufficient to produce a detectable effect on gross reproductive fitness.

A hypothesis concerning the detection of early embryonic and zygotic mortality in oral cleft families is presented. It is suggested that probands from solitary pregnancies are the result of a higher liability to clefting which eliminated potential siblings prior to the conception of the proband. A positive association between the degree of liability to clefting and fetal mortality has already been established by the authors' previous work. In sibships of solitary probands, such liability is assumed to have caused early embryonic and zygotic mortality which eliminated potential siblings and recognizable fetal loss. This hypothesis can be tested by an examination of the sex-ratios in probands from solitary pregnancies and those from multiple pregnancies. For CL(P), a decrease in the proportion of males would be expected in probands from solitary pregnancies in comparison to those from multiple pregnancies. For CP, however, an increase in the proportion of males in solitary probands is expected in comparison to those from multiple pregnancies. This hypothesis is applied to 613 CL(P) probands and 317 CP probands from Indiana. Although the expected decrease (for CL(P)) and increase (for CP) in the proportion of males in solitary probands is not quite significant, the trends are in the expected directions. It is suggested that the hypothesis should be tested further with additional data on oral clefts and other similar anomalies.

Birth intervals in sibships of oral cleft probands are analysed to detect prolonged delays between successive pregnancies. Such intervals are useful indicators of undetected fetal mortality. The present study indicates that the average interval for 462 cleft families in Indiana is 30.61 months. The average interval leading to the birth of a cleft child is 33.94 and is significantly greater than the average interval for the entire sample. Although the contraception status of the Indiana population is not known, the significantly greater delay preceding the birth of a cleft child is indicative of a cause other than contraception. This finding is in agreement with the report by Drillien et al. (1966) that abnormal conceptions occur more frequently adjacent to cleft offspring. It is interesting that some increase in the average interval is also noted in the present study immediately following the birth of a cleft child. Such delays occurring both preceding and following the birth of a cleft child (in contrast to smaller intervals for other pregnancies in the same sibships) may indicate excessive fetal wastage due to a combination of genetic and environmental factors.

Certain fragile sites may possibly predispose to chromosome breakage and rearrangements in meiosis. To test this hypothesis, we examined 894 breakpoints found in spontaneous abortions, stillbirths and livebirths of which 165 (18.5%) were in bands with fragile sites. Compared to an expectation of 98 (11%), there was a significant excess of breakpoints in fragile site bands (P less than 0.001). Together with data from amniocenteses, there is now evidence suggesting that certain fragile sites may be prone to fragility in meiosis.

The autosomal recessive multiple pterygium syndromes are a heterogeneous group of disorders in which multiple joint contractures are associated with cutaneous webbing. Recently, we evaluated a 33 week gestation male in whom multiple pterygia were one feature of a broader pattern of malformation. Clinical management was adversely affected by malignant hyperthermia. In this report we present the clinical, radiographic and pathologic data of this patient and those of an affected stillborn female sibling. We believe that these represent the features of a newly recognized disorder.

Data on parental consanguinity have been recorded for all births in Norway since 1967. Pregnancy outcome for offspring of 848 women mated to their first cousins were compared with offspring of 1,696 control women. The stillbirth rate was 23.6 per thousand for cases and 13.4 for controls. The neonatal death rate was 34.9 per thousand for cases and 14.3 for controls. The recurrence risk for sibs for early death was 9.4% for cases and 4.2% for controls. The mean offspring birth weight was significantly lower (3377 g vs. 3491 g), and the variance in birth weight was slightly larger for cases than controls. The percentage of children with malformations detected shortly after birth was 4.6% for cases and 2.2% for controls. The differences may be attributed to the increased homozygosity in offspring of first cousins. The results have relevance for genetic counselling to consanguineous couples, as well as for the understanding of the etiology of adverse pregnancy outcome and for elucidating the causes of variation in birth weight.

Reciprocal translocations were studied in two groups of balanced carrier couples: 202 had 210 translocation aneuploid between (LB) infants, and 95 couples had repetitive abortions (AB) without liveborn aneuploids. The observed translocation aneuploidies in the LB group were compared to predicted potential aneuploidies in AB by frequency of chromosome involvement, meiotic segregation mode, and mean trisomic, monosomic and combined genomic imbalances. Qualitative and quantitative differences identified genomic regions and chromosomes possibly vital for in utero survivability. LB aneuploidies indicate non-random chromosome involvement, selection of least detrimental segregants and segments, and predominant transmission from maternal balanced carriers (especially in 3:1 tertiary segregation, 93.5%). For an individual with a balanced reciprocal translocation and untested reproductive capability, an approach is given for predicting whether a translocation aneuploid conceptus will be liveborn or aborted.

Analysis of fetal mortality in sibships of 406 probands with cleft lip with or without cleft palate (CL(P)) indicates that the incidence of fetal mortality is significantly greater in sibships of probands with bilateral CL(P) than in those of unilateral CL(P). The difference is even greater when fetal mortality in sibships of male probands with unilateral CL(P) is compared with that of female probands with bilateral CL(P). These findings support a multifactorial two-threshold concept in which a lower level of liability results in clefting while a higher level of liability causes fetal mortality.

Examination of fetal wastage data for a large collection of CL +/- P and CP sibships reported previously (Bear 1978) does not indicate the frequency of recognized abortion to be higher in the sibships of CL + P vs CL index cases, female vs male CL +/- P index cases, bilateral vs unilateral CL +/- P index cases, female bilateral CL +/- P index cases vs male unilateral CL +/- P index cases, or male vs female CP index cases. These observations fail to confirm those reported by Dronamraju (Dronamraju et al. 1982, Dronamraju & Bixler 1983a, b), and provide no evidence of a positive relation between degree of liability to facial cleft malformation and fetal mortality.

A stratified representative sample size of 5,007 Kuwaiti females aged 15 years and above was drawn during 1983 and structurally interviewed to study the influence of consanguineous marriages (up to the second cousin) on reproductive wastage. Losses comprised prenatal deaths (abortions and stillbirths) and neonatal deaths (up to the first month of life). The rate of consanguineous mating in the sample was 54.3% with 95% confidence limits estimated rate 52.9% to 55.7% when projected over the whole Kuwaiti population. First cousin marriages accounted for 30.2% of the sample followed by 22.1% less than first cousin (first cousin once removed and second cousins) and 2% only double first cousin. The study showed higher prenatal and neonatal losses among consanguineous (14.2%, 2.97%) than nonconsanguineous (13.97%, 2.54%) although not statistically significant. No consistent increase in reproductive wastage was evident as the inbreeding coefficient, F, advances mainly because of decline in the wastage rate among the double first cousin marriages which represents only 2% of our sample.

Four families with the cryptophthalmos-syndactyly syndrome are reported. Nine affected patients died in perinatal period. Autopsy, performed in 6 cases, revealed renal agenesis (bilateral in 3 and unilateral in 3 cases). These observations together with recent literature data suggest that renal malformations (agenesis or severe hypoplasia) are one of the most common features of the cryptophthalmos-syndactyly syndrome and may serve as one of diagnostic criteria for this entity.

This report presents a case of cyclopia attributable to an unbalanced karyotype in a family with a balanced, reciprocal 3/7 translocation. This case was the fifth recorded in three generations of this family. From this report it is possible that the simultaneous action of partial trisomy 3p and partial monosomy 7q may be one cause of holoprosencephaly.

Pedigree data on 854 probands with cleft lip and/or cleft palate from the State of Indiana are presented. These include 123 probands with cleft lip alone (CL), 453 with cleft lip and palate (CLP), and 278 with isolated cleft palate (CP). Probands and families were interviewed at the Indiana University Medical Center during the years 1962-1980. Among features of special interest are an excess of bilateral CLP (46% of all CLP cases) and a significantly greater number of older mothers and fathers (over 34 years old) than in the general population. An apparent increase in the proportion of sporadic cases with time may be due to bias in ascertainment. It is suggested that the increased proportions of more severe clefts and older parents are among several factors which contribute to the incidence of fetal mortality in a cleft population. The association of fetal mortality with liability to clefting introduces a more precise way to define a sporadic cleft. That is, a truly sporadic cleft is one conceived as a single occurrence event and has survived to become a liveborn cleft child whereas other apparently sporadic cleft individuals represent the surviving cleft in a sibship in which fetal mortality has eliminated all other cleft offspring already conceived. This observation has applications to the collection and interpretation of genetic pedigree data for clefts as well as many other genetic conditions.

During a 4 1/2-year period a special study of 207 consecutive perinatal deaths, including clinical, genetical, roentgenological and autopsy investigations, was undertaken with the aim of identifying inherited malformations with a high risk of recurrence to subsequent sibs. Fifty-three of the children dying perinatally were malformed. In 13 cases the cause of the malformation was purely genetic; 11 were caused by mutant genes of large effect, and two by chromosomal aberrations. Information from such a study provides a good basis for genetic counselling of the family.

The frequencies of fetal deaths in sibships of oral cleft probands are analysed in relation to sporadic or familial clefts, and pure or syndromic clefts. In a study of 1823 pregnancies in 630 sibships of probands with CL(P), the frequency of fetal deaths was found to be increased, but not significantly, in the sporadic group as compared to the familial group of sibships from Indiana. However, such an increase was found to be significant in the Montreal data. The pooled data from both these centers also show a significant increase in the sporadic group. For CP, no such differences were found. Similar comparisons of fetal mortality in relation to pure and syndromic clefts indicated that the frequencies of fetal deaths were consistently elevated in sibships of probands with syndromic clefts with one exception, which is the Indiana CP group where the lowest frequency of fetal deaths was observed in the sibships. This group mostly consisted of sibships with solitary pregnancies. This may have been a result of early zygotic mortality in this group. Further data will be obtained to confirm this observation.

A second family showing transmission of a dicentric through three generations involving chromosomes 13 and 18 is presented. Features of non-Robertsonian dicentric chromosomes are presented and discussed.

Analysis of 418 sibships of oral cleft probands from Indiana, and 288 sibships from Montreal indicate that the incidence of fetal mortality is significantly greater in sibships of probands with cleft lip and cleft palate (CLP) as compared to that in sibships of probands with cleft lip (CL) alone. These findings support a multifactorial-two-threshold concept, according to which a lower level of liability results in clefting whereas a higher level of liability causes fetal deaths. They add confirmatory evidence in support of the authors' earlier work, utilizing data from two different sources.

We describe a lethal malformation syndrome in 28 newborn infants from 18 families. The main manifestations were hydrocephalus (often with an unusual structure of the brain and the occipital bone), very small mandible, polydactyly, congenital heart defect, abnormalities of the respiratory organs, and (different from the Meckel syndrome) normal kidneys. Polyhydramnios and stillbirth or neonatal death were the rule. Autosomal recessive inheritance is evident. This syndrome is another in the group of rare recessive disorders which are found in Finland. Because of the 25% recurrence risk and possibilities for prenatal diagnosis, this syndrome should be recognized by paediatricians and, because of the frequent stillbirths, also by obstetricians and pathologists. The name hydrolethalus syndrome (hydramnios, hydrocephalus, lethality) may be of help in this.

Fetal mortality data from Lancaster, Penn., Chicago, Ill. and Minneapolis, Minn. are presented which support the authors' earlier findings in Indiana and Montreal that a positive relationship exists between the degree of liability to malformation and the incidence of fetal deaths in probands' sibships. Altogether, the study involved 189 CL sibships, 690 CLP sibships, and 3,416 pregnancies. On the basis of these data, which are derived from families of several different backgrounds of European ancestry, it is generalized that, as we proceed from CL sibships to CLP sibships, there is a doubling effect on fetal mortality. The consistency of this finding in several population samples is impressive. The implications of this observation are discussed with reference to genetic counseling.

Fifteen children with autosomal reciprocal translocations were found in an incidence study of chromosome aberrations among 11,148 consecutively liveborn children in a Danish Maternity Hospital (1.34 per 1,000). The segregation rate of the balanced forms was 60% and that of unbalanced forms 4%; the frequency of familial cases was 73%. None of the probands or their relatives who carried the balanced translocation had any physical or mental abnormalities which could be associated with the chromosome aberration. We found two children with unbalanced translocations among the 45 relatives examined, but more studies of unselected population groups are needed before any segregation rates for unbalanced derivatives of autosomal reciprocal translocations can be estimated. We found a significantly higher frequency of abortions, stillbirths and perinatal deaths in the progeny of carriers with the translocation, compared with non-carriers in the same families. The unbalanced forms of autosomal reciprocal translocations in most cases are probably not compatible with the development of a foetus to a liveborn, healthy child. Fifteen children with 13/14 translocation were found among 11,148 consecutively liveborn children. Incidence, segregation rates and type of translocation are discussed. Fertility and risk for carriers of D/D translocations of producing children with autosomal trisomy are discussed.

The Y/20 ratio (length of Y chromosome/length of chromosome 20) was examined among 216 males, 108 of whose wives had a history of repeated abortions (study group), and 108 who were mentally retarded (controls). There was no significant difference in frequency of long Y (Y/20 equal to or greater than 1) between the study group and controls. Also, there was the expected male: female ratio among normal living children of couples in the study group, and the Y/20 ratio was not significantly increased among fathers with abnormal male offspring. However, wives of long Y males were more likely to have at least one abnormal male birth, compared with other wives (this approached statistical significance, p less than 0.08). In addition, a significantly higher frequency of long Y was found in a subset of affected males whose wives had 2 or more spontaneous abortions plus some other abnormal pregnancy outcome. Although the findings reported here do not strongly support a causal relationship, they at least suggest an association between long Y chromosome and abnormal fetal development.

The point prevalence at birth of osteogenesis imperfecta was estimated by a systematic search of all children born 1. I. 1970 to 31. XII. 1983 in the county of Fyn (Denmark). Additionally, the population prevalence on 31. XII. 1983 of all patients with osteogenesis imperfecta in this county was determined. The county is a well-defined, representative subregion of Denmark which demographically comprises a cross-section including about 9% of the Danish population. Altogether, the study disclosed 48 patients with osteogenesis imperfecta. Of these, 17 patients were born 1. I. 1970 to 31. XII. 1983 and 12 had type I, 2 had type II, 2 had type III, and 1 had type IV. Thus, the point prevalence at birth was 21.8/100,000 and the population prevalence was 10.6/100,000 inhabitants. There was great variation in the clinical manifestations within and between the types.

Analysis of data from 56,664 marriages in Turkey studied from 1970 to 1988 showed an overall rate of consanguineous marriages, of 21.25%, and increases in the rates of abortions, stillbirths, prenatal losses and neonatal deaths.