Biomedical subjects
Publications and source records attributed to H Rehder.
Clinical and autopsy findings in two fetuses and one newborn infant with Fraser syndrome are presented. Discussion focuses on the range of phenotypic expression within this autosomal-recessive disorder, the resulting difficulties in prenatal and postnatal diagnosis, and on the concept of a neurocristopathy as underlying disturbance.
Fourteen (2.5 per cent) of 568 chromosome preparations after CVS showed discrepancies between the placental and fetal karyotype, mainly due to placental mosaicism. The presence of a second cell line within the placenta was confirmed in all but one case, in which cytogenetic reinvestigations were carried out. Our clinical data indicate that severe developmental retardation in the newborn is not to be expected if only the placenta carries the chromosomally abnormal cell line.
A retrospective study of 200 missed abortions was performed to determine whether morphological criteria alone are sufficient to ascertain a chromosomal aetiology. Placental changes were classified into five morphological and four morphometric groups, according to the severity of alterations, and were then correlated with the cytogenetic data. The rate of chromosome anomalies was approximately 50% and was thus not significantly different within the groups II-V, but it was 80% in group I, which covered the most severe placental alterations, namely the partial hydatidiform moles. There was a high incidence of triploidies in group I, trisomies with obligatory early lethality in groups II and III, and X-monosomies in group III. Our findings do not support previous evidence regarding the specificity of certain villous alterations in association with chromosome aberrations. Indeed, they indicate that the placental villi may react similarly to chromosomal and non-chromosomal disturbances and that placental morphology depends on the severity and the temporal onset of the underlying disorder rather than on its type. With respect to chorionic villus samplings (CVS), this would mean that an abnormal villous structure may be suggestive for a chromosome anomaly but does not exclude a normal karyotype.
Stamping-out of animals in case of infections diseases has to meet the requirements resulting from animal welfare, disease prevention, and practicability under conditions in practice. This is well qualified by application of electrical shock stunning with subsequent generation of ventricular fibrillation in cattle, swine and sheep. The scientific elements of the method, the procedure, and experiences in application of the method during the stamping-out of 340 cattle, 980 swine, 152 sheep and 18 goats are discussed in the paper.
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In a previous radiographic study on the feet of 71 adults with trisomy 21 we found, in comparison to control individuals, an increased prevalence of biphalangeal toes and metatarsophalangeal sesamoid bones. The present histological study on the feet of 21 mid-trimester fetuses with prenatally diagnosed trisomy 21 confirms results of the earlier study. At both stages of development these minor bone anomalies have about the same frequency, thus suggesting 1) that they are selectively neutral, and 2) that they reflect a basic (innate) failure of ordered morphogenesis. Our observation that the normal spatial pattern of skeletal variants is reproduced in trisomy 21 simply on a quantitatively higher level lends sound support to the hypothesis of amplified developmental instability in chromosome trisomies.
Cardiac defects were studied in five chromosomally abnormal embryos of 10-14 weeks' gestation by free-hand microdissection of hearts measuring 2.5-6 mm in diameter. The type of cardiac malformation alone or in association with other anomalies helped to confirm the chromosome diagnosis established prenatally by chorionic villus sampling or after spontaneous abortion. It was suggestive of a chromosomal disorder in one case in which cytogenetic investigation had failed.
New molecular techniques concerned with the isolation and identification of DNA fragments can be used for carrier detection and early prenatal diagnosis either by direct detection of the mutant DNA sequence or by indirect linkage studies employing RFLPs as DNA markers. Gene specific DNA probes are available already for a number of genetic disorders, such as the hemoglobinopathies, hemophilia A and B, alpha 1-antitrypsin deficiency, phenylketonuria, and chronic granulomatous disease. Coinheritance of DNA-polymorphisms can be traced, eg, for Norrie disease, myotonic dystrophy, Duchenne and Becker muscular dystrophies, and Huntington chorea. Several genes have been localized successfully to specific chromosome regions. By "walking" or "jumping" along the chromosome, it is hoped finally to reach further gene loci of interest, to analyze the molecular pathology of single gene disorders, and to find new ways for their prevention.
New insights into gene structure and expression and the observation that homeobox-containing genes, the t-complex, and oncogenes are expressed also in humans contribute to the understanding of normal and pathobiological mechanisms of embryonal and fetal development.
Light and electron microscopic studies on testicular biopsies were carried out in two men, 40 and 44 year old, with the fra(X) form of mental retardation and macroorchidism. Distinct interstitial edema, an increased amount of lysosomal inclusions in Sertoli cells, and disturbance of spermatid differentiation were found in both probands. Additionally, some extent of tubular atrophy was demonstrated in one patient. The impairment of spermatogenesis is discussed with respect to pressure effects on the germinal epithelium due to the edema.
A family with three siblings showing different manifestations of Roberts syndrome or SC phocomelia is described. With regard to previously published cases of familial Roberts syndrome and SC phocomelia we conclude that these two syndromes are one and the same genetic entity.
A fetus with tetrasomy for the short arm of chromosome 12 due to a de novo accessory isochromosome i(12p) is described. Involvement of the 12p in this chromosome aberration was suggested by banding analysis and substantiated by detection of a marked increase of LDH-B in the fetal fibroblasts. The syndrome shown by this fetus includes many of the minor anomalies described for live-born patients with partial trisomy 12p, and in addition malformations including brachymelia, anal atresia and double kidneys.
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A woman with severe pre-eclampsia refractory to treatment was examined in the 22nd week of pregnancy by ultrasound. This revealed a big renal cyst in the foetus and discrete signs of a partial hydatidiform mole. The pregnancy was terminated, chromosome analysis confirmed the presence of foetal triploidy, and the symptoms of severe pre-eclampsia disappeared immediately. This case illustrates that ultrasound can guide the obstetric management in the right direction, if the initial examination is performed early enough.
A second case of fetal XXXXY-syndrome detected by prenatal chromosome analysis is presented. The pathological findings include a facial aspect featuring fetal Down's syndrome, hypogenitalism and hypogonadism with excessive reduction of germ cells and also skeletal abnormalities that may be interpreted as early changes, preceding phalangeal shortening V and radioulnar synostosis.
The Ivemark-Syndrome (Alienie Syndrome) is defined by the characteristic association of splenic aplasia, organsymmetry and other malformations especially of the cardiovascular system. More than 200 cases are reported. The incidence of Ivemark-Syndrome is very low. The aetiology is not yet clearly defined. As a main cause exogen factors between the 31st and 38th day of gestation are discussed, but a genetic cause has not been detected yet. Due to the unfavourable prognosis an intensive ultrasonographic screening is to be asked for.
This is a report of monoamniotic-monochorionic (ie, probably MZ) twins, one of which had anencephaly, whereas the co-twin died of complications of prematurity. Autopsy in this seemingly nonmalformed twin showed a small encephalocele. The literature on MZ twins with discordant anencephaly is often contradictory. It is suggested that this might be due to the difficulty of determining zygosity on the one hand and identifying discordance or concordance on the other. This case is presented as an example of this difficulty; it is discordant with respect to anencephaly, but concordant in the sense of "dysraphic" disturbances.
A case of a triploid embryo (69,XXX) resulting from in vitro fertilization is reported. The pregnancy ended in spontaneous abortion 44 days after embryo transfer. The embryo showed anomalies considered typical of triploidy but molar changes were not noted. The origin of extra chromosomes was apparently maternal.