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The cytogenetic and bioinformatic models of ancestral genome reconstruction are compared and the resulting models are verified to discuss the reasons for their apparent divergence. The apparent conflict between the two models may, in part, reflect limited taxon sampling in the bioinformatic analysis coupled to an algorithm that does not provide for evolutionary rate variation among lineages.

A search for sex chromosomal mosaicism in gonads of patients with XY or XY gonadal dysgenesis of undetermined origin is discussed. The result indicates that sex chromosomal mosaicism in gonads may be a frequent cause of gonadal dysgenesis despite of normal karyotypes in lymphocytes.

To preserve material for future genetic studies, human B-lymphocytes from whole blood samples are routinely transformed into lymphoblastoid cell lines (LCLs) by in vitro infection with Epstein–Barr virus. To determine the rate and frequency of chromosomal changes during long-term culture, we established 10 LCLs (from eight individuals). Before transformation, these cases showed a normal karyotype (three cases), a small supernumerary marker chromosome (three cases), or an aberrant karyotype (four cases). Chromosome analyses were performed at 8-week intervals over a period of at least 1 year, up to 3 years. Surprisingly, we demonstrate that chromosomal instability is the rule, rather than the exception, during long-term culture of LCLs. The most commonly observed acquired clonal aberration was trisomy 12, which emerged in all cell lines within 21 to 49 weeks after infection. Telomeric fusions indicating telomere shortening were found after ~21 weeks. After 1 year of cultivation, the proportion of cells with the original karyotype decreased to ≤10% in 7 of the 10 cell lines. To preserve cells with aberrant genomes, we conclude the cultivation time of LCLs must be restricted to the absolute minimum time required:

AbstractWe present 2 cases with multiple de novo supernumerary marker chromosomes (sSMCs), each derived from a different chromosome. In a prenatal case, we found mosaicism for an sSMC(4), sSMC(6), sSMC(9), sSMC(14) and sSMC(22), while a postnatal case had an sSMC(4), sSMC(8) and an sSMC(11). SNP-marker segregation indicated that the sSMC(4) resulted from a maternal meiosis II error in the prenatal case. Segregation of short tandem repeat markers on the sSMC(8) was consistent with a maternal meiosis I error in the postnatal case. In the latter, a boy with developmental/psychomotor delay, autism, hyperactivity, speech delay, and hypotonia, the sSMC(8) was present at the highest frequency in blood. By comparison to other patients with a corresponding duplication, a minimal region of overlap for the phenotype was identified, with CHRNB3and CHRNA6as dosage-sensitive candidate genes. These genes encode subunits of nicotinic acetylcholine receptors (nAChRs). We propose that overproduction of these subunits leads to perturbed component stoichiometries with dominant negative effects on the function of nAChRs, as was shown by others in vitro. With the limitation that in each case only one sSMC could be studied, our findings demonstrate that different meiotic errors lead to multiple sSMCs. We relate our findings to age-related aneuploidy in female meiosis and propose that predivision sister-chromatid separation during meiosis I or II, or both, may generate multiple sSMCs.© 2015 S. Karger AG, Basel

The discovery of copy number variations (CNV) in the human genome opened new perspectives in the study of the genetic causes of inherited disorders and the etiology of common diseases. Differently patterned instances of somatic mosaicism in CNV regions have been shown to be present in monozygotic twins and throughout different tissues within an individual. A single-cell-level investigation of CNV in different human cell types led us to uncover mitotically derived genomic mosaicism, which is stable in different cell types of one individual. A unique study of immortalized Blymphoblastoid cell lines obtained with 20 year interval from the same two subjects shows that mitotic changes in CNV regions may happen early during embryonic development and seem to occur only once, as levels of mosaicism remained stable. This finding has the potential to change our concept of dynamic human genome variation. We propose that further genomic studies should focus on the single-cell level, to understand better the etiology and physiology of aging and diseases mediated by somatic variations.

Cases of tetrasomy 12p and trisomy 12p are known to be associated with specific phenotypic abnormalities well described in the literature. Here, we report on the unusual case of a partial tetrasomy 12p found in an affected patient and in a mosaic constellation in the patient's mother, who showed no phenotypic abnormality. The index patient was a 16‐year‐old boy with clinical features similar to the “trisomy 12p syndrome” including mental retardation, macrocephaly, a short nose with anteverted nostrils, and a broad protruding lower lip. G‐banding analysis and fluorescence in situ hybridization (FISH) experiments using locus specific YAC DNA probes revealed a derivative chromosome 12 with a partial triplication of the short arm with an inverted copy, flanked by two direct copies. Chromosome analyses in parental lymphocytes showed a chromosomal mosaicism in the phenotypically normal mother, with 12% cells exhibiting the same partial tetrasomy 12p as detected in her son. The allelic pattern of short tandem repeats (STR) in the mother's blood DNA showed that a chimerism can be excluded with high probability. To our knowledge, this is the first report of intrachromosomal triplication on chromosome 12, as well as partial tetrasomy 12p mosaicism. Moreover, as a consequence of the chromosomal aberration in the son it can be concluded that a gonadal mosaicism is present in the mother. © 2006 Wiley‐Liss, Inc.

Reports on patients with pure and complete trisomy 12p are rare. Up to now, 12 cases have been described in the literature. Here, we report on the genotype/phenotype‐correlation of a female patient with a pure trisomy 12p. Conventional cytogenetic studies on peripheral blood chromosomes as well as molecular cytogenetic (fluorescence in situ hybridization, FISH) techniques including whole chromosome painting (WCP), comparative genomic hybridization (CGH), multicolor‐banding (MCB) detected a female karyotype with an abberant chromosome 12:46,XX,der(12).ish dup(12)(pter → q24.3::p11.2 → pter). In addition to the trisomy 12p specific clinical hallmarks, the patient showed some features of Pallister–Killian syndrome (PKS) such as sparse hair, macroglossia, and epilepsy. These findings contribute to the genotype/phenotype correlation in trisomy 12p patients. © 2004 Wiley‐Liss, Inc.

Glossophaga soricina is a flower-visiting bat which lives in the neotropics. The diploid chromosome number is 2n = 32 with a fundamental number of autosomal arms, FN, of 60. G. soricina belongs to the Microchiroptera which have a lower diploid DNA content and a higher AT composition in their DNA compared with other mammals. By ZOO-FISH analysis with human chromosome-specific DNA probes, the human autosomes were found conserved in 41 segments. This is an arrangement similar to other mammals which have been analyzed. Several chromosomal associations already known from ZOO-FISH studies in other species were also present in G. soricina.

Using ecoethology of bats and statistical methods, we anticipate the evidence of specific species of spinturnicids associated with Myotis myotis and Myotis bechsteinii (Chiroptera, Vespertilionidae) mixed colonies are unknown. Traditional description of this new crpytic species Spinturnix bechsteini, parasite of M. bechsteinii, is done. Statistical approach is based on analysis of variance and principal component analysis. The current knowledge on parasites of the genus Myotis in the West Palearctic subregion is presented.

Chromosomal characteristics seem to play a crucial role for the analysis of the phylogenetic relationships within the plecotine bats, as shown by a comparison of results obtained from morphological and chromosomal data with those from morphology only. Published descriptions of karyotypes of the genera involved, however, are based on different chromosome-banding qualities and even contain several errors. We compare the different results using our own published chromosomal data and present a revised scheme of the chromosomal complements of the plecotine genera.