Characterization of hypervariable locus-specific probes derived from a (CAC)5/(GTG)5 multilocus fingerprint in various Eurasian populations

Professor Andrew E. Czeizel, Hungary (April 3, 1935–August 10, 2015)

We are sad to announce the passing of Andrew E. Czeizel on August 10, 2015, at the age of 80, after a long-lasting illness.

Psychosexual Study of Communist Era Hungarian Twins

Our aim in this study is to describe the characteristics of sexual development in twins and estimate the role of heritability and environmental factors as causes of certain sexual disorders. Two hundred and ten adult same-sex twin pairs (92 monozygotic [MZ] female, 41 MZ male, 55 dizygotic [DZ] female and 22 DZ male pairs) were involved in the study. Data were collected in 1982 by self-administered questionnaires that included items on sexual maturation, sexual life, contraception, mutual sexual activity within twin pairs and alcohol use. The ratio of married to unmarried twins was nearly the same in MZs and DZs, with the exception that the divorce rate was higher in MZ female twins (14%), and DZ and male twins were slightly more likely to be single. Menarche was later in twins compared to non-twin Hungarian women. 57% of MZs experienced menarche within 3 months of each other, 77% within 6 months while it occurred for 30% and 43% respectively in DZs. The first seminal emission indicated some delay in male twins compared with the Hungarian general population sample. MZ first kisses occurred later than DZ's first kisses. The same was true for the first petting, masturbation and first sexual intercourse. Anorgasmy is 27% heritable but the estimate is not statistically significant. Concordance rate for premature ejaculation in MZs was greater than in DZs but the structural equation model showed significant misfit. Age at menarche appeared to be strongly heritable.

The properties of human DNA fingerprints produced by polymeric monocore probes (PMC probes)

The properties of human DNA fingerprints detected by multilocus polymeric monocore probes (PMC probes) have been investigated. The PMC probes were produced by the polymerase chain reaction with two partly complementary oligonucleotides homologous to various minisatellite or microsatellite core sequences (Ijdo J, Wells RA, Baldini A, Reeders ST. Nucleic Acids Res 1991;19:4780). It has been shown that these probes possess increased sensitivity, they detect considerably more hypervariable fragments in genomic DNA thus exhibiting advantages over the corresponding oligonucleotides and natural polycore minisatellite probes. Variation in the DNA fingerprints of different individuals produced by these probes indicates that the probability of accidental identity is very low (< 10(-12)). According to the data of cross-hybridization with PMC probes of various specificity, several distinct families can be distinguished among G-rich hypervariable sequences of the human genome.

CAC--the neglected repeat

It is becoming increasingly clear that repetitive DNA is of biological significance as well as experimental importance. Here we review the information available about one type of repetitive DNA, the trinucleotide repeat (CAC)n, and briefly compare it with other trinucleotide repeats. Although much work has been done in analysing DNA fingerprinting patterns produced using the synthetic oligonucleotide (CAC)5 as a probe, there is relatively little information about individual (CAC)n-containing sequences and their abundance, organisation and distribution in mammalian DNA. From the data that is available, it is clear that there are at least two areas that should repay further study: (1) the organisation and generation of long sequences that contain (CAC)n motifs as part of a larger repeating unit (minisatellites) and (2) the distribution of small (CAC)n sequences (microsatellites), in particular their relationship to genes.

Recent observations in human DNA-minisatellite mutations

We report maternal and paternal mutation rates at loci D1S7 (MS1), D7S21 (MS31), D12S11 (MS43A), and D7S22 (G3). The respective mutation rates were as follows: [table: see text] At loci D7S21, D12S11, and D7S22 statistically significant differences in mutation rates exist between the sexes. No such difference was observed at locus D1S7. However inspection of the latter data reveals that by mutation at spermiogenesis approximately two-thirds of the fragments showed an addition of repetitive units, while a 50: 50 ratio was encountered in the series of maternal mutations. We also report the observation of naturally occurring 3-fragment patterns.

The incidence of mini- and micro-satellite repetitive DNA in the canine genome

We have estimated the incidence of microand mini-satellites in the dog genome. A genomic phage library from canine liver, with an average insert size of 16 kb, was screened to detect potentially polymorphic microand mini-satellite sequences, which may be useful for the development of markers of inherited diseases, for fingerprinting, or for population genetics. Synthetic oligonucleotide probes were used to search for microsatellite sequences, and minisatellites were investigated with eight heterologous VNTR probes. (CA)n.(GT)n sequences were by far the most frequent, with a calculated average distance between consecutive loci of 42 kb. The average distance between loci of tri- or tetra-nucleotide repeats was about 330 kb. Mean inter-locus distances were 320 kb for (GGC)n, 205 kb for (GTG)n, 563 kb for (AGG)n, 320 kb for (TCG)n, 233 kb for (TTA)n, 384 kb for (CCTA)n, 368 kb for (CTGT)n, 122 kb for (TTCC)n, 565 kb for (TCTA)n, and 229 kb for (TAGG)n. Cross-hybridization with eight human minisatellite probes was found at average distances of 1400 kb; only one did not hybridize at all. We conclude that the di-, tri and tetra-nucleotide short tandem repeats, as well as some minisatellite sequences, are potentially useful as genetic markers, for mapping of the canine genome, and also for paternity testing and the analysis of population characteristics.

On the essence of "meaningless" simple repetitive DNA in eukaryote genomes

Various kinds of simple tandemly repetitive DNA sequences are abundantly interspersed in the genomes of practically all eukaryotic species studied. The comparatively elevated mutation rates of simple repeat blocks result in highly polymorphic and therefore extremely informative investigation systems for studies on forensic, ecological and genetic relationship questions. Recently the techniques for analyzing simple repeats have achieved great effectivity and simplicity. Beyond their utility as tools for differentiation and individualization, certain of these repeated elements harbor quite unexpected qualities which may be discussed in the context of their biological meaning. i) A specific subset of simple (cac)n or (gtg)n repeats is expressed in mature mRNA and total cellular RNA. ii) Despite the apparently high mutation rate certain (gt)n or mixed (gt)n/(ga)m stretches of intronic simple repeats are preserved in immunologically relevant genes for at least 70 x 10(6) years and they bind nuclear protein molecules with high affinities. Consequently in addition to their tool character, the biological aspects of simple repeated DNA should be taken into consideration.

On the potential of simple repetitive DNA for fingerprinting in clinical, forensic, and evolutionary dynamic studies

The purpose of this review is to discuss critically the practical meaning of a specific genome component, simple repetitive desoxyribonucleic acid (DNA) sequences as clinical and forensic and diagnostic and research tools. Previously, multilocus DNA fingerprinting was the major technology employed to visualize such simple repeat sequences. This technique enables many polymorphic loci to be simultaneously detected thus yielding vast amounts of information. With the advent of enzymatic DNA amplification via the polymerase chain reaction (PCR), individual simple repeat loci can be demonstrated, theoretically even from single DNA molecules and so a wealth of additional approaches have also become feasible. In general investigating, small, known, single copy parts of genomes have not posed truly insurmountable problems if enough material was available. There have even been a few (anecdotal) reports on the amplification of simple repeats from ancient DNA (see, e.g. [30]. Here we would like to after a solid basis for an earnest discussion of the applications of these simple repetitive sequences using various methodological approaches relevant for clinical diagnosis, setting aside the obvious unsolved mysteries of their biology.

Dissecting (CAC)5/(GTG)5 multilocus fingerprints from man into individual locus-specific, hypervariable components

Individual components of multilocus fingerprints from man produced by (CAC)5/(GTG)5 oligonucleotides have been scrutinized to characterize their peculiar properties. Successful cloning and changes occurring during the propagation of recombinant simple repetitive DNA in prokaryotic hosts are described. The isolated locus-specific probes were characterized with respect to their formal (and population genetic) properties and their usefulness for individualization and linkage studies. The localization was determined on chromosomes 8, 9, 11, and 22. Repeat flanking sequences were characterized and analyzed for their coding potential because of significant open reading frames and apparent evolutionary conservation among vertebrates. The organization of the repeats and their flanking regions in the human genome is discussed with respect to the sequence (fine) architecture that developed during evolution. Classical "minisatellite" sequences were not detected near hypervariable (cac)n/(gtg)n repeats. The single-copy probes described herein are a convenient complement to the oligonucleotides employed for multilocus fingerprinting. Many practical applications are apparent.