Specific transcriptional changes in human fetuses with autosomal trisomies.

Among full autosomal trisomies, only trisomies of chromosome 21 (Down syndrome), 18 (Edwards syndrome) and 13 (Patau syndrome) are compatible with postnatal survival. But the mechanisms, how a supernumerary chromosome disrupts the normal development and causes specific phenotypes, are still not fully explained. As an alternative to gene dosage effect due to the trisomic chromosome a genome-wide transcriptional dysregulation has been postulated. The aim of this study was to define the transcriptional changes in trisomy 13, 18, and 21 during early fetal development in order to obtain more insights into the molecular etiopathology of aneuploidy. Using oligonucleotide microarrays, we analyzed whole genome expression profiles in cultured amniocytes (AC) and chorionic villus cells (CV) from pregnancies with a normal karyotype and with trisomies of human chromosomes 13, 18 and 21. We observed a low to moderate up-regulation for a subset of genes of the trisomic chromosomes. Transcriptional levels of most of the genes on the supernumerary chromosome appeared similar to the respective chromosomal pair in normal karyotypes. A subset of chromosome 21 genes including the DSCR1 gene involved in fetal heart development was consistently up-regulated in different prenatal tissues (AC, CV) of trisomy 21 fetuses whereas only minor changes were found for genes of all other chromosomes. In contrast, in trisomy 18 vigorous downstream transcriptional changes were found. Global transcriptome analysis for autosomal trisomies 13, 18, and 21 supported a combination of the two major hypotheses.

Loss of the Y chromosomal PAR2-region in four familial cases of satellited Y chromosomes (Yqs).

Applying fluorescence in-situ hybridization (FISH) of various Y chromosomal DNA probes to four familial cases of human Yqs, it was possible to demonstrate that the formation of Yqs must have arisen from a reciprocal translocation involving the short arm of an acrocentric autosome and the heterochromatin of the long arm of the Y chromosome (Yqh). Breakpoints map within Yqh and the proximal short arm of an acrocentric autosome resulting in the gain of a nucleolus organizer region (NOR) including the telomere repeat (TTAGGG)n combined with the loss of the pseudoautosomal region 2 (PAR2) at the long arm of the recipient Y chromosome. In no case could the reciprocal product of an acrocentric autosome with loss of the NOR and gain of PAR2 be detected. Using the 15p-specific classical satellite-III probe D15Z1 in two of the four Yqs probands presented here, it could be shown that the satellited material originated from the short arm of chromosome 15. In contrast to the loss of PAR2 in Yqs chromosomes, another Y chromosomal variant (Yqh-) showing deletion of long-arm heterochromatin in Yq12 has retained PAR2 referring to an interstitial deletion of Yq heterochromatin in such deleted Y chromosomes.

A novel ribosomal S6-kinase (RSK4; RPS6KA6) is commonly deleted in patients with complex X-linked mental retardation.

Large deletions in Xq21 often are associated with contiguous gene syndromes consisting of X-linked deafness type 3 (DFN3), mental retardation (MRX), and choroideremia (CHM). The identification of deletions associated with classic CHM or DFN3 facilitated the positional cloning of the underlying genes, REP-1 and POU3F4, respectively, and enabled the positioning of the MRX gene in between these genes. Here, we report the cloning and characterization of a novel gene, ribosomal S6-kinase 4 (RSK4; HGMW-approved symbol RPS6KA6), which maps in the MRX critical region. RSK4 is completely deleted in eight patients with the contiguous gene syndrome including MRX, partially deleted in a patient with DFN3 and present in patients with an Xq21 deletion and normal intellectual abilities. RSK4 is most abundantly expressed in brain and kidney. The predicted protein of 746 amino acids shows a high level of homology to three previously isolated members of the human RSK family. RSK2 is involved in Coffin-Lowry syndrome and nonspecific MRX. The localization of RSK4 in the interval that is commonly deleted in mentally retarded males together with the high degree of amino acid identity with RSK2 suggests that RSK4 plays a role in normal neuronal development. Further mutation analyses in males with X-linked mental retardation must prove that RSK4 is indeed a novel MRX gene.

Identification of a hot spot for microdeletions in patients with X-linked deafness type 3 (DFN3) 900 kb proximal to the DFN3 gene POU3F4.

Small mutations in the POU domain gene POU3F4 were recently shown to cause X-linked deafness type 3 (DFN3) in nine unrelated males. The POU3F4 gene was found to be located outside four of five deletions associated with DFN3. Two of these deletions were situated more than 400 kb proximal to POU3F4. Employing PCR analysis of sequence tagged sites from this region we initially identified novel deletions in two DFN3 patients. To investigate this chromosomal segment in more detail, we extended a previously established 850 kb cosmid contig in the centromeric direction to a total size of 1500 kb. Cosmids from this contig were hybridized to DNA of 11 unrelated males with DFN3. In two patients, we identified deletions encompassing the POU3F4 gene and variably sized segments of Xq21.1. In six of the nine remaining patients which lacked mutations in the POU3F4 gene, smaller deletions were identified which, with one exception, overlap in a 8 kb segment 900 kb proximal to the POU3F4 gene. In one patient, we identified several small deletions in the vicinity of the 8 kb DNA segment. Together, deletions account for 56% (13/23) of all known DFN3 mutations, most (10/13) of which do not encompass the POU3F4 gene. The combined molecular data suggest that the deletion hot spot region in Xq21.1 contains another DFN3 gene or, alternatively, a sequence element involved in transcriptional regulation of POU3F4.

[Sex chromosome aberration with the 48 XYYY karyotype. A case report of the phenotype of a rare sex chromosome aneuploidy]. / Geschlechtschromosomenaberration mit dem Karyotyp 48, XYYY. Ein Fallbericht zum Phänotyp einer seltenen geschlechtschromosomalen Aneuploidie.

This is a case report on a 19-year-old patient with the chromosome constellation 48, XYYY. The patient showed signs of dysmorphism, mental retardation and problems in psychosocial functioning. A literature review revealed that individuals with this karyotype have widely varying phenotypes with regard not only to physical signs but also to brain functions and cognitive performance.

Molecular analysis of mutations in the gene FMR-1 segregating in fragile X families.

Molecular genetic analysis of the transmission of mutations in 73 families with fragile X (one of the largest samples evaluated so far) has confirmed previous hypotheses that the fragile X syndrome results from two consecutive mutational steps, designated "premutation" and "full fragile X mutation". These mutations give rise to expansions of restriction fragments, most probably by amplification of the FMR-1 CGG repeat. Premutations are identified by small expansions that apparently have no effect on either the clinical or the cellular phenotype. Full mutations are reflected by large expansions and hypermethylation of the expanded gene region. All males showing large expansions were affected. Individuals with full mutations also expressed the fragile X, with only one exception. An affected "mosaic" male, showing a predominance of premutated fragments in his leukocytes, was shown to be fragile-X-negative on different occasions. About 50% of heterozygotes with full mutations were reported by clinicians to be mentally retarded. Conversion of the premutation to the full mutation may occur at oogenesis, as previously suggested, or after formation of a zygote at an early transitional stage in development when the CGG repeat behaves as a mitotically unstable element on maternally derived/imprinted X chromosomes carrying a premutation of sufficient repeat length.

Characterisation of a Xp21 microdeletion syndrome in a 2-year-old boy with muscular dystrophy, glycerol kinase deficiency and adrenal hypoplasia congenita.

We report a 2-year-old boy with Duchenne muscular dystrophy (DMD), glycerol kinase deficiency (GK) and adrenal hypoplasia congenita (AHC). At three weeks of age, the patient was hospitalized for the first time with symptoms of hypotone dehydration because of AHC. At present, he shows severe muscular hypotonia and developmental delay. The patient and his family were referred to us for prenatal diagnosis and carrier testing in the mother of the patient and the mother's sister, respectively. The patient's DNA was examined by Southern blot and polymerase chain reaction analyses, using cDNA and genomic probes within and around the dystrophin (DYS) locus. A deletion was revealed, spanning DXS28, the whole dystrophin locus, DXS84 and DXS148, whereas DXS67, DXS68 (pter) and OTC (cen) were found to be retained. The cytogenetically visible microdeletion was also seen in the patient's mother, but not in the mother's sister or the patient's maternal grandmother. Our findings support the locus order pter-DXS67-DXS68-DXS28-AHC-GK-DMD-cen.

Cell fusion responsible for horizontal oncogenesis by human tumors in nude mice.

Human tumor xenotransplants derived from 4 different carcinomas were established in athymic mice and maintained by serial passage. In vivo human/mouse cell fusion and induction of neoplastic growth of adjacent mouse tissue was investigated in serial passages by isoenzyme analysis, by chromosome analysis and by cloning of induced tumorigenic mouse cells. In 2 xenotransplants human/murine hybrid isoenzyme complexes of pyruvate-glutamate transaminase, glucosephosphate isomerase and mitochondrial malate dehydrogenase were detected. Metaphases containing human and murine chromosomes were found in the first in vitro passage of excised xenotransplants. Cloning of induced mouse tumor cells yielded tumor cell lines tumorigenic in athymic as well as in immunocompetent mice.

Satellited Y chromosomes: structure, origin, and clinical significance.

Three cases of inherited satellited Y chromosomes (Yqs) were analysed using several cytogenetic techniques. The cytogenetic data of the 14 cases of Yqs chromosomes described to date were reviewed. All Yqs chromosomes carry an active nucleolus organizer region (NOR) in their long arm and must have developed from translocations involving the short arms of the acrocentric autosomes. The structure of the heterochromatic satellite region in the Yqs chromosomes shows conspicuous inter-familial differences; this permits the reconstruction of the translocations from which the various Yqs were derived. Some causal factors leading to the development of Yqs chromosomes are considered: the specific localization of the four satellite DNAs and highly methylated DNA sequences in the karyotype, and some new experimental data on the spatial arrangement of heterochromatic regions in interphase nuclei. These provide distinct evidence for a preferential involvement of the autosomes 15 and 22 in the translocations with the Y heterochromatin. All clinical reports documenting Yqs males born with malformations were reviewed. It appears that the presence of an extra NOR and NOR-associated heterochromatin in the Yqs chromosomes does not cause any phenotypic abnormalities (as long as the Y euchromatin is intact). The possibility that a Yqs chromosome predisposes to non-disjunction and/or to translocations of other chromosomes is discussed.

In vivo induction of neoplastic growth in nude mouse connective tissue adjacent to xenografted human tumors.

Induction of neoplastic growth of murine stroma cells within the human tumor xenograft was observed after serial passage of CEA and beta 2-microglobulin producing human colonic SLu tumor xenografts in nu/nu BALB/c mice. Mouse tumors within the human tumor xenografts were identified using specific immunohistologic staining techniques for mouse histocompatibility marker or human CEA. These mixed tumors could be distinguished from normal human tumor xenografts by a different relationship between development of the tumor marker in the serum and tumor size. We were able to establish transformed murine cells from human xenografts, either induced by SC injection of 1 X 10(6) tumor cells of the SLu cell line or by human SLu or mammary carcinoma tissue serially passaged in athymic animals. The established human and murine cell lines were characterized by cytogenetic methods. Transformed murine cells were then continuously passaged in tissue culture. The transformed mouse fibroblasts proved to possess tumorigenicity in nude mice. In the case of SLu-derived mouse tumor cells, tumors also developed in the immunocompetent BALB/c mice using 1 X 10(6) to 5 X 10(6) tumor cells for SC transplantation.

Amniotic fluid levels of 17 alpha-hydroxyprogesterone during human pregnancy: pre-natal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

Levels of 17 alpha-hydroxyprogesterone were estimated by radioimmunoassay in 174 amniotic fluid specimens obtained from 162 normal pregnancies of 16-20 weeks gestation. Another 18 specimens from 11 normal pregnancies between 25-42 weeks gestation and 7 specimens from 7 women who each previously had given birth to a child affected with CAH were also studied. There was no sex difference in AF 17 alpha-OH-progesterone levels, nor any significant downward trend in concentrations throughout the observed gestation period. Among the 7 subjects with previous history of CAH offsprings, 4 demonstrated normal levels of AF 17 alpha-OH-progesterone and 3 significantly higher values. HLA-typing of the cultivated amniotic cells confirmed these 4 cases to be heterozygous for 21-hydroxylase deficiency. The three subjects with high AF 17 alpha-OH-progesterone levels delivered babies affected with CAH, although HLA-typing in one case was non-conclusive. The failure of HLA-typing in 1 case for a confirmatory diagnosis indicates that the prenatal diagnosis of CAH must continue to rest on joint endocrinological and genetical investigations.

[Prenatal diagnosis of Gaucher's disease (author's transl)]. / Pränatale Diagnose der Gaucher-Krankheit.

Gaucher's disease type I was diagnosed prenatally in one case. Using radiomarked natural lipid substrate the enzyme defect was demonstrated in amniotic cells cultured after amniocentesis in the 16th week of pregnancy. Rest activity of cerebroside beta-glucosidase was around 6% of control activity. After termination of pregnancy in the 19th week the diagnosis was confirmed in the fetus by demonstration of lack of enzyme activity in fetal fibroblasts and liver tissue. Enzyme levels of cerebroside beta-glucosidase in blood leucocytes of the couple who decided on termination of the pathological pregnancy were found compatible with but no proving the heterozygote state of Gaucher's disease. In the future the enzyme defect of affected probands should be determined early and as precisely as possible.

Data on linkage relations between GLO and 21-hydroxylase.

Linkage between GLO and 21-hydroxylase was investigated in 11 families with 24 children. Positive lod score values with a maximum of +1.618 at theta = 0.05 indicate close linkage between these marker loci.

[Chromosome studies on trichloroethylene workers (author's transl)]. / Cytogenetische Untersuchungen an Trichloräthylen-Arbeitern.

On the basis of lymphocyte cultures, chromosome studies were carried out on 28 degreasers under different trichloroethylene load. Nine of these cases showed pathological rates of hypodiploid cells, but otherwise normal caryotypes; one case had a caryotype 47,XY,+mar (small metacentric extrachromosome). In these nine cases the trichloroethylene load, but not the exposure periods on the working place were significantly higher than in the control group.