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Congenital diaphragmatic defects (CDD) are easily accessible to ultrasonographic diagnosis. In spite of progress in the management of prenatally detected cases, the mortality rate for CDD remains high. The prognosis depends mainly on the severity of fetal lung hypoplasia but is also linked to the associated malformations. We report on 77 cases of CDD ascertained between 1982 and 1988 from 136,161 consecutive births in the Bouches du Rhône area. The spontaneous perinatal mortality rate was 61% with 28 early post-natal deaths and 14 stillbirths. Eight pregnancies were terminated after prenatal diagnosis. The diaphragmatic defect was associated with other congenital anomalies in 33 cases, more often among stillborn (92.8%) than liveborn infants (23.6%). A chromosomal abnormality was present in 9 cases representing 11.6% of all CDD and in 27.2% of cases with other anomalies. A Mendelian disorder was present in 9 cases (eight Fryns syndrome and one Fraser syndrome). This study underlines the necessity of a systematic work up of prenatally diagnosed cases, including fetal karyotyping and analysis of associated malformations in order to adapt the management of the pregnancy and delivery to the prognosis.

There were 18 individuals found to have a constitutional chromosome fragility causing an increase in break frequency. For each chromosome the breakpoint is always the same, whether it involves chromosomes from the same person, the same family, or different families. The fragile points are bands 10q24, 12q13, 16q21, 17p12, and Xq27. Autosomal constitutional fragility does not seem to have a phenotypic correspondence. They were found mostly in parents of children with chromosomal abnormalities or in couples with a history of repeated spontaneous abortions which permits one to raise the possibility of an interchromosomal effect. The six constitutional chromosomal fragilities of the X chromosome had in common the association of mental deficiency, delayed speech, and large malformed ears. The break points in constitutional chromosomal fragility were compared to those of spontaneous breaks in vitro, to those induced by X-rays, and to those in Fanconi's anemia. The theoretical consequences of these structural abnormalities are discussed as well as what to do about them when they are found.

Of 61 families of children with trisomy 21, polymorphism of chromosome 21 elucidating the origin of the extra chromosome was found in 42. Nondisjunction was of paternal origin in 8 cases (19.04%) and the anomaly occurred with equal frequency during the first and second meiotic divisions. Maternal nondisjunction was demonstrated in 34 cases (80.95%), in which nondisjunction occurred by far the most often during the first meiotic division (29 cases). These results are in agreement with data from the literature, and suggest the existence of at least two different causes for chromosomal nondisjunction, the first being the same in both sexes and occurring in both meiotic divisions and the second specifically limited to the first meiotic division in the mother.

Three patients have been detected because of abnormal phenotypes. Balanced chromosome rearrangements were found in their karyotypes, and in one of the parents in each case. In these three families the association of an abnormal phenotype and a balanced chromosome rearrangement may either be a chance happening or be induced by a submicroscopic loss of chromosome material, for which different position effects may be responsible, according to the case in question. These observations prompt us to ask what decision should be made relative to termination of pregnancy if such a rearrangement is found in amniotic cells in a family with a previous abnormal child.

The authors discuss the clinical and cytogenetic problems raised in two new cases of X-chromosome translocations. The first case involves a child who presented marked malformations at age 3 months. Chromosome analysis revealed the presence of a translocation between a 22 and X chromosome resulting in partial X monosomy and partial trisomy 22: 46,X,der(X),t(X:22)(q112;q13)mat. The balanced translocation form was detected in the mother. Dynamic study after 5-Brdu treatment revealed inactivation of the translocated X chromosome in the proband, while in the mother the normal X chromosome was inactivated. In addition to magnesium dependent hypocalcemia resulting from a specific absorption anomaly, Case 2 presented discrete malformations and psychomotor retardation. Chromosome analysis revealed an apparently balanced translocation between a 9 and X chromosome: 46,X,t(9;X)(q12;p22). Treatment with 5-Brdu demonstrated that the translocated X chromosome was inactivated but that inactivation did not extend to the translocated part of chromosome 9. Finally, a pericentric inversion of a 9 chromosome was detected in the father, grandfather, and brother of the proband.

Three new observations of trisomy 4p are reported. Two are due to a maternal translocation t(4;15). The third is due to a "mirror" duplication, it is the first case of trisomy 4p without balanced parental rearrangement. The very characteristic phenotype is compared to that of 13 other patients already reported in the literature.

Chromosomal analysis of 100 second metaphases from 19 men attending an infertility clinic for various reasons was carried out to estimate the rate of non-disjunction occurring at first meiotic division. Second metaphases were selected on the basis of the good spread of their chromosomes. Karyotypes were performed using the relative length of the chromosomes and the centromeric index. Among aneuploid cells, only those containing a hyperhaploid complement (24) were regarded as informative. Of the 100 MII cells, two were hyperhaploid. The frequency of aneuploid MII cells following non-disjunction at first meiotic division is compared to the rate of aneuploid spermatozoa observed after using fertilization of zona-free golden hamster eggs.

This study involving 109 normal subjects shows that the mean number of associations by cell seems to represent a biological constant which is not sex related and increases with age, especially after 33 years. From a qualitative point of view, the associations are not at random and their distribution varies from one individual to another. The tendency to associate is a characteristic of a given chromosome in a given individual.

The acrocallosal syndrome is characterized by peculiar facies, polydactyly of the hands and/or feet, and agenesis of the corpus callosum. Two unrelated 4-month-old boys with consanguineous parents are reported. Both exhibited the main features of the syndrome, but neither of them had partial reduplication of halluces. Consequently, pre-axial polydactyly of the feet is not considered to be a constant feature of the acrocallosal syndrome. The similarity of the acrocallosal syndrome to Greig syndrome is discussed, but it appears unlikely that the two syndromes are identical. Consanguinity in both cases is a strong argument in favour of a recessive mode of inheritance.

To define the principal characteristics of X-autosome translocations, the authors present a study of 105 cases, five of which are personal observations. The autosomal pairs 15, 21, and 22 are affected by t(X-Aut) more often than would be expected. The distribution of breakpoints on the X chromosome does not differ significantly from the expected distribution. The analysis of different patterns of inactivation seems to confirm that the inactivation could occur at random, but would be followed by a cellular selection favoring the better genetic balance. An estimate of the incidence of t(X-Aut) is proposed, based upon the conclusions that only one chromosome is susceptible to translocation in meiosis in both males and females and that all affected men will be sterile, as will be 50% of women.

The authors studied 17 cases of Robertsonian translocation. In all cases but one C banding showed that a dicentric translocation was involved. Silver staining demonstrated the presence of an NOR between the two centromeres in only one case.