Pigmentary mosaicism in hypomelanosis of Ito. Further evidence for functional disomy of Xp

We report on a female with mental and motor retardation, facial dysmorphism, abnormal pigmentation reminiscent to hypomelanosis of Ito (HI), and karyotypic mosaicism involving a small supernumerary marker chromosome. The marker chromosome was defined by fluorescence in situ hybridisation (FISH) as a ring X chromosome with breakpoints in the juxtacentromeric region. FISH analysis showed that the ring does not include the XIST locus at the X-inactivation centre and, therefore, may not be subject to X inactivation. X-inactivation studies with the HUMARA (human androgen receptor) and FMR1 assay showed a skewed X-inactivation pattern (85:15) with preferential inactivation of the paternal X chromosome. These results are discussed with respect to the role of functional disomy of Xp in the pathogenesis of HI.

Prenatal diagnosis and fetopathological findings in a fetus with ring chromosome 18

We report on a fetus with ring chromosome 18 and monosomy 18 mosaicism [mos 45,XX,-18/46,XX,r(18)] detected in cultured amniotic fluid cells at 15 weeks' gestation. Chromosome analysis of fetal blood, cultured chorionic villi and fetal fibroblasts confirmed the aberrant karyotype. The aberrant chromosome complement could not be detected in a short-term culture of chorionic villi (46,XX in 21 metaphases). These findings suggest that the aberrant karyotype was a postzygotic event. Fetal ultrasound was normal and the parents decided to terminate the pregnancy at 21 weeks' gestation. Autopsy revealed multiple abnormalities including facial dysmorphy, partial agenesis of the corpus callosum and an interatrial septal defect.

Thanatophoric dysplasia type I: new radiologic, morphologic, and histologic aspects toward the exact definition of the disorder

A comprehensive seven-step study on THANATOPHORIC DYSPLASIA without cloverleaf skull (TD Type I) was carried out postmortem on three aborted fetuses of 19, 26-27, and 34 weeks and one preterm neonate of 35 weeks gestation, respectively. The characteristic x-ray configuration of the spine in TD Type I presenting with H-, U- or reversed U-shape vertebrae were shown to correlate with the inclination or reclination of the vertebral bodies within a kyphotic or lordotic segment. The bowing of the tubular bones in TD Type I is explained by a diminished mechanical stability that is causally related to a specific cartilage structure. The perichondral spurs are defined by their morphologic structure, and their origin is attributed to a normal perichondral ossification in the presence of an impaired enchondral ossification. Impairment of enchondral ossification was more evident in the periphery than in the center of the metaphyses leading to a tongue-shaped osseous cone directed toward the epiphysis. The perichondral spurs and the linguiform enchondral growth plate resulted in a three-phase maple leaf-like contour of the metaphyses of tubular bones and acetabular roof. The nature of the perichondral fibrous bands, the fibrovascular bundles, and the fibrovascular bands of the growth plate and their significance in atypical ossification processes are discussed in detail. It is suggested that the diminished longitudinal growth of the skeleton is caused by a reduced mitotic activity of cartilage cells in the proliferative zone leading to a reduction of cell numbers in the columnar zone transversely oriented spongiosa bars resulting from desmal ossification of the metaphyseal fibrovascular structures.

Cystic hygroma as an early first-trimester ultrasound marker for recurrent Fryns' syndrome

We present a case of a fetus who at a 12-week ultrasound examination was shown to have a large cystic hygroma. Fryns' syndrome was suspected because the mother's previous pregnancy had been affected by the condition. Pathological examination confirmed the diagnosis at this early stage of gestation. In families with increased risk for Fryns' syndrome, first-trimester ultrasound screening should be offered to exclude cystic hygroma as an ultrasound marker for this most often lethal malformation.

Neural tube defects in chromosomally normal and abnormal human embryos

Neural tube defects (NTDs) were recognized in eight out of 91 intact embryos from spontaneous abortions and in one case of an induced abortion following prenatal diagnosis of a chromosomal disorder. Five of the nine cases showed chromosomal abnormalities. Trisomy 18 and triploidy were associated with spina bifida in three cases, trisomy 7 with parieto-occipital encephalocele and monosomy X with spina bifida and iniencephaly in one case. A sixth anencephalic embryo in which chromosomal analysis was not performed showed a malformation pattern highly suggestive for trisomy 18. Discussion focuses on the high rate and the type of chromosomal abnormalities among spontaneously aborted NTD embryos, on the contrasting phenotype of 45,X conceptions and on the morphogenesis of the different neural tube defects in early development. In view of future early endovaginal ultrasound diagnosis, the changing morphological pattern is exemplified, and ranges from apparently hyperplastic to degenerative alterations of the exposed neural tissue.

Microdeletion 22q11 in complex cardiovascular malformations

Besides DiGeorge, velocardiofacial and conotruncal anomaly face syndromes, some of the isolated congenital heart diseases have also been associated with a chromosomal deletion in 22q11. These disease entities, which had originally been considered to have a different genetic background, are now included in the CATCH-22 microdeletion complex. CATCH 22 is an acronym for cardiac defect, abnormal facies, thymic hypoplasia or aplasia and T-cell deficiency, cleft palate, hypoparathyroidism, and hypocalcemia. In the present study, we focused on the complex cardiovascular defects (CCVD) and screened 40 patients for a microdeletion of 22q11 by fluorescence in situ hybridization using the D22S75 DNA probe and for associated CATCH features. The patients were from genetic counseling (n = 15) or fetopathology (n = 3) of the Clinical Genetics Department in Marburg and from the Pediatric Cardiology Department (n = 22) in Mainz. Monosomy 22q11 was detected in 9 cases (= 22.5%). Familial transmission with one mildly affected parent and one affected sib each was proven in two cases. The CCVDs comprised complex conotruncal defects such as tetralogy of Fallot, double outlet right ventricle, transposition of great arteries and truncus arteriosus communis, or anomalies of the derivatives of the branchial arch arteries in association with a ventricular septal defect, including one case of atresia of the ductus arteriosus with pulmonary artery aneurysm and resulting in fetal hydrops. All 13 patients with a deletion of 22q11 showed at least one additional CATCH symptom. Most consistently, facial dysmorphy was apparent (92%), while hypocalcemia, mostly at threshold values, was present in 62% and thymic hypoplasia including borderline low T-lymphocyte numbers was observed in 41%. None of the patients presented with a cleft palate. A high intrafamilial variability in expression was also evident with respect to the CCVD. Our findings indicate that seemingly isolated complex cardiovascular defects associated with a 22q11 microdeletion most probably do not represent a distinct subgroup within the CATCH-22 complex but are syndromal in nature with extracardiac features that are often overlooked.

[Possibilities for false-negative findings in trisomy 21 screening with FISH]

In approximately 5% of individuals with Down syndrome aneuploidy results from a chromosomal rearrangement. FISH analysis on chromosome metaphases and interphase nuclei of 5 individuals with Down syndrome carrying different types of chromosome 21 translocations demonstrated the diagnostic efficiency of this method. By use of different commercially available chromosome 21 specific probes we were able to show that only the cosmid probe specific for the Down syndrome critical region (DCR) in 22qll gave reliable results for interphase analysis of trisomy 21, while the use of chromosome 21 centromere- or of painting probes carry a high risk of a false-negative diagnosis in translocation trisomy 21.

VACTERL with hydrocephalus and branchial arch defects: prenatal, clinical, and autopsy findings in two brothers

VACTERL association is defined as a combination of vertebral, anal, cardiac, tracheoesophageal, renal and limb anomalies, in particular radial defects. In recent years hydrocephalus was observed in patients with apparent VACTERL association. This particular condition was recognized as a hereditary entity with poor prognosis. Both autosomal recessive and X-linked forms were described. Here we report prenatal, clinical and autopsy findings in 2 brothers with this syndrome, who had, in addition, branchial arch anomalies. The recurrence in this family suggests X-linked inheritance. Branchial arch defects have so far not been described as part of the VACTERL+H syndrome. This observation further supports that a variety of brain anomalies including hydrocephalus associated with VACTERL anomalies represents separate entities with a considerable recurrence risk. The use of the term VACTERL "association" for these conditions is misleading and is discouraged.

[A new punch technique of cartilage-bone tissue for morphological studies in orthopedics]

A new technique is presented for the analysis of tissues which allows an exact, detailed comparison of light and electron microscopy. For this purpose, the previous techniques required the cutting of tissue pieces from the original tissue compound and the preparation of drawings as a rough localisation of the tissue pieces removed for analysis. Due to the processes of cutting and drawing, only an approximate localisation of the tissue investigated by electron microscopy was practicable. Specifically, the exact analysis of fetal cartilage-bone-tissue was mostly not possible due to the complicate arrangement of both tissue components. Therefore, the assessment of electron microscopic analyses was severely limited. The new technique, presented in this study, is characterised by a removal of punches 1 mm in diameter from the original tissue for electron microscopy. The remaining tissue with its exact defined punch-punctures is prepared for standard histology. Thus, the specific advantage of this new method is the precise attribution of the punched tissue to the original tissue group. Human fetal cartilage-bone-tissue has been used to demonstrate this punch-technique and the specific light- and electron microscopic preparations.

Parental origin of the extra haploid chromosome set in triploidies diagnosed prenatally

The parental origin of the additional chromosome complement in a total of 17 cases of triploidy was determined mainly using highly polymorphic microsatellites. Maternal origin of the triploidy was demonstrated in most cases. To the best of our knowledge, this is the first systematic evaluation of the parental origin of chromosome sets in fetuses who survived until a cytogenetic diagnosis was established. In contrast to previous investigations this study documented a predominance of maternal origin of the extra haploid set mainly due to longer survival time for digynic triploidies. The concept of 2 distinct fetal phenotypes in triploidy is clearly supported by this study.

Extreme hypotrophy of the lower body pole, extensive hypoplasia of the spinal column and multiple anomalies of abdominal organs: a maximal variant of the caudal regression sequence?

A newborn with extreme hypotrophy of the lower body pole and aplasia of the lower spinal column is reported. Additional anomalies of internal organs included absence of one kidney and ureter, a diaphragmatic hernia, and anal atresia. Part of the organs located in the lower body pole were necrotic. There were no excretory apertures, and external genitalia were absent. Chromosomal analysis revealed a 46,XY karyotype. The multiple anomalies seen in this newborn may be interpreted as a maximal variant of the caudal regression sequence.

[Familial akinesia-hypokinesia sequence (Pena-Shokier phenotype)]

The Pena Shokeir phenotype (PSP) is characterised by multiple ankyloses, camptodactyly, facial dysmorphisms and lung hypoplasia with hydramnios. The basic neuromuscular defect leads, through a fetal hypokinesia-akinesia, to the development of this nonspecific phenotype and a respiratory insufficiency with early postnatal mortality. Severe central nervous anomalies are described in one-third of the reported cases. In this paper a foetus with PSP and 4 further foetuses with severe cerebral malformations and only discrete lung hypoplasia are described. It is not clear whether the cerebral malformations represent a primary or secondary developmental defect.

[Pathologic embryo examinations of induced and spontaneous abortions in the 1st trimester of pregnancy]

Morphological examination methods which are appropriate for detection of embryonic developmental defects are presented. The main emphasis is put on autopsy of small embryos using a dissection microscope and on documentation of the embryonic skeleton by means of skeleton staining. Through presentation of the embryopathological findings in 15 first-trimester abortion specimens we demonstrate that these examination techniques frequently allow diagnosis of isolated malformations as well as malformation syndromes, even in the fragmented or macerated embryo. Careful embryopathological examination and evaluation is a precondition for genetic counselling, as well as for goal-directed prenatal diagnostic measures in future pregnancies.

Craniofacial anomalies, abnormal hair, camptodactyly, and caudal appendage (Teebi-Shaltout syndrome): clinical and autopsy findings

Teebi and Shaltout [1989: Am J Med Genet 33: 58-60] described a new syndrome of craniofacial anomalies, abnormal hair, camptodactyly, and caudal appendage in children born to a consanguineous couple. We report on a second family with the same pattern of anomalies occurring in a liveborn female and 3 spontaneously aborted fetuses, and include autopsy findings. As additional findings 2 of our cases had unilateral microphthalmia and kidney anomalies. Our observation confirms that this pattern of anomalies is a distinct syndrome with autosomal recessive inheritance; we suggest the synonym Teebi-Shaltout syndrome.

The insulin-like growth factor type-2 receptor gene is imprinted in the mouse but not in humans

In mouse, four genes have been found to undergo genomic imprinting resulting in differential expression of maternally and paternally inherited alleles. To determine whether the cognate genes are also subject to imprinting in humans, we have studied allele-specific expression patterns of insulin-like growth factor 2, IGF2-receptor and H19 in human fetal and adult tissues. In keeping with previous findings in mice, our results indicate that in human fetal tissues the paternal H19 alleles is inactive. IGF2 is monoallelically expressed in various tissues but surprisingly not in adult human liver. The human IGF2R gene, another classic example of imprinting in mice, was found to be expressed from both alleles. We provide the first direct evidence for differential imprinting in the human and murine genome.

Polyploidies in abortion material decrease with maternal age

Among 639 spontaneous abortions between the 8th and 14th week of gestation 342 (53.5%) revealed an abnormal karyotype. While the rate of trisomies distinctly increased with advancing maternal age, a decrease in the rate of 45,X conceptuses and polyploidies was observed among abortions from older women. The overall relation of XXXX:XXYY among the tetraploidies was 14:11 and that of XXX:XXY:XYY among the triploidies was 26:36:1. However, when the latter was related to maternal age, a reversal of the XXX:XXY ratio of 1:2 in the younger to 2:1 in the older age groups became evident. Furthermore a decrease in the rate of "paternally" derived partial hydatidiform moles was found among the triploid abortion specimens from older women. From these observations we conclude that digyny plays a major role in the origin of triploidy in the increased maternal age groups, while diandry related to immaturity of oocytes and impairment of oocyte cortical function is more frequent in triploid abortions from younger women.

New autosomal recessive lethal disorder with polycystic kidneys type Potter I, characteristic face, microcephaly, brachymelia, and congenital heart defects

We report on 3 pairs of sibs from unrelated families, who present with polycystic kidneys Potter type I claimed to be specific for the ARPKD, and with microbrachycephaly, hypertelorism with telecanthus, large posteriorly angulated fleshy ears and various congenital malformations including congenital heart defects. We suggest that they represent a previously unrecognized autosomal recessive lethal developmental disorder within the group of infantile polycystic kidney disease and Potter sequence.

A case of full triploidy (69,XXX) of paternal origin with unusually long survival time

Triploidy is a rare disorder in live-born children and these infants generally die within the first hours after birth. We report here on a girl with full triploidy and multiple malformations, who survived for 10 1/2 weeks. The extra set of haploid chromosomes was of paternal origin, as shown by chromosomal banding techniques.

Fluctuations in nitrate reductase activity, and nitrate and organic nitrogen concentrations of succulent plants under different nitrogen and water regimes

The CAM (Crassulacean acid metabolism) succulent species Kalanchoe daigremontiana, K. tubiflora and Crassula argentea, and the succulent C₃ species Peperomia obtusifolia, were cultivated in pure culture in open-air conditions under two different regimes of nitrogen and water supply. At specified intervals during the course of vegetative growth, biomass, nitrate reductase activity (NRA), nitrate concentration, and organic nitrogen concentration of whole plants were measured. After 100 days of cultivation the leaf conductance of Crassula and Peperomia was measured at intervals for the duration of a day. Behaviour of all four species was strongly influenced by the cultivation regime. This was apparent in terms of productivity and variable flucturations in NRA, nitrate concentration, and organic nitrogen concentration during the vegetative period. Increase in biomass was mostly connected with a decrease in all other investigated parameters, especially under conditions of water and/or nitrogen deficiency. The typical reaction of the CAM species Crassula to limited netrogen but adequate soil water was to reduce leaf conductance during light, whereas the C₃ plant Peperomia increased conductance in comparison with plants having a nitrogen suppy. The NRA of all plant species was reduced by both soil nitrate deficiency and drought. The succulent plant species, which are specially adapted to drought, neither took up nor used nitrate when water was limited. This was particularly the case for the CAM species, but less so for the C₃ Peperomia, which showed very high concentrations of nitrate and organic nitrogen, but low NRA and biomass gain. A formula was derived to express the nitrogen use efficiency (NUE) of the species, i.e. the ability of a plant to use nitrogen over a specific period of growth. NUE was shown to increase with age for the crassulacean species but to decrease for the C₃ Peperomia. Furthermore, NUE varied with the different nutrient levels in a species-specific manner, with high values for NUE not necessarily coupled to high productivity, and with NUE of the C₃ species generally higher than that of CAM species.

Prenatal diagnosis of the Pallister-Killian mosaic aneuploidy syndrome by CVS

Prenatal cytogenetic analysis at 11 weeks of gestation revealed an abnormal karyotype 47,XX,+mar in all metaphases obtained from a chorionic villi sample after 24 h culture. Karyotyping of amniotic fluid cells in the second trimester showed mosaicism 47,XX,+i(12p)/46,XX with 10% aneuploid cells. The pregnancy was terminated at 20 weeks of gestation on the patient's request. The aborted fetus showed typical manifestations of the Pallister-Killian mosaic aneuploidy syndrome. The identity of the supernumerary isochromosome 12p was proven by LDH isozyme electrophoresis using cultured fibroblasts and by nonradioactive in situ hybridization using a biotinylated set of chromosome 12-specific DNA probes.

[Diagnosis of fetal virus infections by in situ hybridization]

Non-radioactive in situ hybridization of formalin-fixed paraffin-embedded placental and foetal tissue, using virus-specific DNA or RNA probes, may be helpful for the diagnosis of foetal virus infection causing foetal hydrops, granulomatous placentitis and abortion. We present four cases of intrauterine CMV-, Parvo-B19- and Varicella-Zoster virus infection, in which this diagnostic method established detection of the virus.