Walther Vogel

Predisposing Gene for Early-Onset Prostate Cancer, Localized on Chromosome 1q42.2-43

There is genetic predisposition associated with >=10% of all cancer of the prostate (CaP). By means of a genomewide search on a selection of 47 French and German families, parametric and nonparametric linkage (NPL) analysis allowed identification of a locus, on chromosome 1q42.2-43, carrying a putative predisposing gene for CaP (PCaP). The primary localization was confirmed with several markers, by use of three different genetic models. We obtained a maximum two-point LOD score of 2.7 with marker D1S2785. Multipoint parametric and NPL analysis yielded maximum HLOD and NPL scores of 2.2 and 3.1, respectively, with an associated P value of . 001. Homogeneity analysis with multipoint LOD scores gave an estimate of the proportion of families with linkage to this locus of 50%, with a likelihood ratio of 157/1 in favor of heterogeneity. Furthermore, the 9/47 families with early-onset CaP at age <60 years gave multipoint LOD and NPL scores of 3.31 and 3.32, respectively, with P = .001.

Visualization of the conservation of synteny between humans and pigs by heterologous chromosomal painting

By comparative gene mapping, extended conservation of synteny between different mammalian species has become apparent. Mapping in these species could be accelerated by exact visualization of the chromosomal segments that exhibit conserved synteny. We have hybridized human chromosome-specific DNA libraries onto porcine metaphase spreads to examine the extent of conservation of synteny between the two species. The hybridization signals on pig chromosomes are of variable quality, but the analysis allowed us to assign for all human autosomes homologous chromosomal segments in the pig karyotype. Extended conservation of synteny was observed, often comprising whole chromosomes. In our analysis 47 segments of conserved synteny common to the human and pig karyotype were identified. Intrachromosomal rearrangements by inversion within and between these segments are described. These rearrangements are common events during evolution. Our analysis shows that conservation of synteny between human and pig is three times more than between humans and mice and, consequently, is characterized by fewer, but larger conserved segments.

A high density of X-linked genes for general cognitive ability: a run-away process shaping human evolution?

The incidence of mental disability is 30% higher in males than in females. We have examined entries in the OMIM database that are associated with mental disability and for several other common defects. Our findings indicate that compared with the autosomes, the X chromosome contains a significantly higher number of genes that, when mutated, cause mental impairment. We propose that these genes are involved in the development of cognitive abilities and thus exert a large X-chromosome effect on general intelligence in humans. We discuss these conclusions with regard to the conservation of the vertebrate X-chromosomal linkage group and to human evolution.

DNA replication patterns of human chromosomes from fibroblasts and amniotic fluid cells revealed by a Giemsa staining technique

A technique is described for visualizing late-replicating regions by a Hoechst 33258-Geimsa-staining procedure combining the techniques of Latt (1973) and of Perry and Wolff (1974). The advantages are two-fold: distinct bands are obtained and many possible mistakes and interpretation difficulties with autoradiography are avoided. The time sequence of late-replication patterns (excepting C-group chromosomes) has been established in human fibroblasts of adults, and these results have been compared with three of four different cell types from amniotic fluid. No significant differences in late-replication patterns and time sequence of the different cells could be discovered. As expected, the replication patterns are in good concordance with the patterns of G- and Q-bands. Some exceptions are described.

Unusual mutations in high functioning fragile X males: apparent instability of expanded unmethylated CGG repeats.

We report on further cases of high functioning fragile X males showing decreased expression of FMR1 protein, absence of detectable methylation at the EagI site in the FMR1 gene promoter, and highly unusual patterns of fragile X mutations defined as smear of expansions extending from premutation to full mutation range. Very diffuse and therefore not easily detectable patterns of full mutations were also observed on prenatal testing using DNA from chorionic villi sampled at a time of development when full mutations were still unmethylated in this particular tissue. In the search for possible determinants of such unusual patterns, repeat expansions in the premutation and in the lower full mutation range were identified on genomic PstI blots previously prepared for fragile X DNA testing. Cases with 130 or more triplets, and a number of shorter repeats, were reinvestigated on EcoRI plus EagI digests. Among the 119 expansions, there were 22 in our sample showing either blurred bands or smears on PstI blots. This particular characteristic was strongly associated with the coincidence of a repeat size of more than 130 triplets and absence of EagI site methylation. Our data set also includes cases of mosaic patterns consisting of smears of unmethylated expansions to more than 130 CGGs and of clear bands of methylated expansions. We therefore suggest that in fragile X syndrome unusual smeared patterns of mutations result from somatic instability of larger repeats under circumstantial absence of repeat methylation.

Fine-mapping identifies multiple prostate cancer risk loci at 5p15, one of which associates with TERT expression

Associations between single nucleotide polymorphisms (SNPs) at 5p15 and multiple cancer types have been reported. We have previously shown evidence for a strong association between prostate cancer (PrCa) risk and rs2242652 at 5p15, intronic in the telomerase reverse transcriptase (TERT) gene that encodes TERT. To comprehensively evaluate the association between genetic variation across this region and PrCa, we performed a fine-mapping analysis by genotyping 134 SNPs using a custom Illumina iSelect array or Sequenom MassArray iPlex, followed by imputation of 1094 SNPs in 22 301 PrCa cases and 22 320 controls in The PRACTICAL consortium. Multiple stepwise logistic regression analysis identified four signals in the promoter or intronic regions of TERT that independently associated with PrCa risk. Gene expression analysis of normal prostate tissue showed evidence that SNPs within one of these regions also associated with TERT expression, providing a potential mechanism for predisposition to disease.

Increased noise as an effect of haploinsufficiency of the tumor-suppressor gene neurofibromatosis type 1 in vitro

In human diseases related to tumor-suppressor genes, it is suggested that only the complete loss of the protein results in specific symptoms such as tumor formation, whereas simple reduction of protein quantity to 50%, called haploinsufficiency, essentially does not affect cellular behavior. Using a model of gene expression, it was presumed that haploinsufficiency is related to an increased noise in gene expression also in vivo [Cook, D. L., Gerber, A. N. & Tapscott, S. J. (1998) Proc. Natl. Acad. Sci. USA 95, 15641–15646]. Here, we demonstrate that haploinsufficiency of the tumor-suppressor gene neurofibromatosis type 1 (NF1) results in an increased variation of dendrite formation in cultured NF1 melanocytes. These morphological differences between NF1 and control melanocytes can be described by a mathematical model in which the cell is considered to be a self-organized automaton. The model describes the adjustment of the cells to a set point and includes a noise term that allows for stochastic processes. It describes the experimental data of control and NF1 melanocytes. In the cells haploinsufficient for NF1 we found an altered signal-to-noise ratio detectable as increased variation in dendrite formation in two of three investigated morphological parameters. We also suggest that in vivo NF1 haploinsufficiency results in an increased noise in cellular regulation and that this effect of haploinsufficiency may be found also in other tumor suppressors.

Sex determination in Ellobius lutescens: The story of an enigma

The unusual karyotype of Ellobius lutescens (2n = 17,X in males and females) has attracted permanent interest and prompted a series of hypotheses on sex determination in this species since its first description by Matthey (1953). The developing knowledge about the sex chromosomes and sex determination as well as the availability of new cytogenetic and molecular genetic techniques prompted studies to test the compatibility between current hypotheses and new findings and rendered modifications of the hypotheses necessary. After a long period dominated by the question what the sex chromosome constitution of this species might be and where the testis determining factor could be located, the presence of Sry had been eventually excluded and sex determination attributed to a hypothetical mutated gene acting downstream of Sry. An X-chromosomal or autosomal location of this gene can be assessed by cosegregation of sex with X-chromosome markers. Some preliminary results concerning X-chromosome dinucleotide repeat markers are reported. However, these markers were homomorphic in Ellobius lutescens. We now report evidence that Zfy is also missing in Ellobius lutescens and E. tancrei (males and females XX), a finding from which we conclude that the entire Y chromosome has been lost from these species. Perspectives concerning future studies are discussed.

Linkage of aggressive prostate cancer to chromosome 7q31-33 in German prostate cancer families

It has been suggested that chromosome 7q32 contains genes that influence the progression of prostate cancer from latent to invasive disease. In an attempt to confirm this linkage to prostate cancer aggressiveness, 100 German prostate cancer families were genotyped using a panel of eight polymorphic markers on chromosome 7q. We used a multipoint allele sharing method based upon a likelihood ratio test implemented in GENEHUNTERPLUS v1.2 in order to calculate the nonparametric Zlr and the associated LOD scores. We applied the aggressiveness of prostate cancer given by the pathological tumour grade of each individual, and the mean age of onset of a family as covariates, and constructed two weighted models. The first (weight0–1 model) puts weights on families with at least two cases of GIII prostate cancer. The second (weight0–2 model) also adds weights to families with early and late onset cancer respectively. The unweighted analysis gave no evidence of linkage to chromosome 7q. The Zlr scores increased when including the covariates, to 2.60 (P=0.005) using the weight0–1 and to 3.02 (P=0.001) using the weight0–2 model for late onset prostate cancer. The associated LOD scores were respectively 1.47 (P=0.009) and 1.98 (P=0.002). The markers that gave most evidence for linkage were exactly in the range of the published prostate cancer aggressiveness region. Our results support a widespread relevance of this locus and suggest that aggressive and late onset prostate cancer is linked to chromosme 7q31-33 in the German population.

Characterization of FMR1 Promoter Elements by In Vivo-Footprinting Analysis

Fragile X syndrome is associated with silencing of the FMR1 gene. We studied the transcriptional regulation, by analysis of the FMR1 promoter region for the presence of in vivo protein/DNA interactions and for cytosine methylation at the single-nucleotide level. Four protein-binding sites were present in the unmethylated promoter of the active FMR1 gene. In the methylated promoter of inactive genes no footprints were detected, and no evidence of active repression was found in the region investigated. We propose that the silencing of FMR1 gene transcription results from a lack of transcription-factor binding.