ABSTRACT
The genotypes of 36 Y-chromosomal short tandem repeat (Y-STR) marker units were analysed in a Dutch population sample of 2085 males. Profiling results were compared for several partially overlapping kits, i.e. PowerPlex Y, Yfiler, PowerPlex Y23, and two in-house designed multiplexes with rapidly mutating Y-STRs. Nineteen Y-STR marker units, of which two are rapidly mutating, reside in at least two of these multiplexes, and for these markers concordance testing was performed. Two samples showed discordant genotyping results and the probable causative base change was revealed by Sanger sequencing. In addition, we encountered concordant, but aberrant genotyping results including one allele with low peak height and several null alleles. For 12 samples, this involved a null allele in two adjacent loci suggesting a large and recurrent deletion as the samples represent three distinct haplogroups. For each marker unit, the allele counts and frequencies are presented, as are the haplotype counts and haplotype diversities for several combinations of markers.
Subject(s)
Chromosomes, Human, Y , Genetic Markers , Microsatellite Repeats/genetics , Electrophoresis, Capillary , Humans , Male , Netherlands , Pedigree , Polymerase Chain ReactionABSTRACT
Recombination can result in genetic instability, and thus constitutes an important factor in the carcinogenic conversion of mammalian cells. Here we describe the occurrence of UV-stimulated recombination called enhanced recombination (EREC), measured with the use of Herpes Simplex Viruses type 1 mutants. In normal diploid human cells, EREC is induced by UV-C, mitomycin C and ENU, but not by X-ray or MMS. The kinetics of induction of EREC is similar to that of other SOS-like responses such as enhanced reactivation (ER) and enhanced mutagenesis (EM). In contrast to the latter responses, EREC is induced to higher levels and persists for longer periods in DNA repair deficient fibroblasts derived from xeroderma pigmentosum (XP), Cockayne syndrome (CS) and Trichothiodystrophy (TTD) patients. This observation indicates that EREC is a distinct SOS-like response. Apparently, the presence of unrepaired DNA lesions in the host genome is a strongly inducing signal for EREC. On the other hand, in cells derived from patients suffering from Bloom, Werner or Rothmund-Thomson syndrome (RTS) the EREC response is absent. These data indicate that determining EREC is a useful assay to investigate diploid human fibroblasts for abnormalities in UV-stimulated recombination.
Subject(s)
Cockayne Syndrome/genetics , DNA Repair , Hair Diseases/genetics , Recombination, Genetic , Xeroderma Pigmentosum/genetics , Animals , Cells, Cultured , Cricetinae , Cricetulus , DNA Damage , Dose-Response Relationship, Radiation , Fibroblasts/metabolism , Fibroblasts/radiation effects , Herpesvirus 1, Human/genetics , Humans , Kinetics , Mutation , Skin/cytology , Time Factors , Ultraviolet RaysABSTRACT
Xeroderma pigmentosum (XP) patients are deficient in nucleotide excision repair (NER) because of mutations in one of the genes coding for NER enzymes. This results predominantly in high frequency of UV-induced skin tumors at an early age; the most severe phenotype is found in patients of complementation group A (XPA). However, in a subset of these XPA patients no skin tumors appear, even at advanced age. Fibroblasts of this subset of patients are not capable of raising UV-induced enhanced reactivation (ER) of viruses and up-regulation of ornithine decarboxylase (ODC). We hypothesized that prevention of ODC induction would protect NER-deficient patients from cancer. To simulate the situation in XPA patients, we used a hairless Xpa knockout mouse model and down-regulated the ODC activity by difluoromethylornithine (DFMO) administered in the drinking water. The DFMO treatment significantly suppressed UV-induced carcinogenesis. In a crossover study, we additionally found that discontinuation of the DFMO treatment resulted in a rapid appearance of skin tumors, up to levels found in mice not treated with DFMO. Late-stage DFMO treatment significantly reduced the number of carcinomas by a factor of 2-3, and it appeared to select for carcinomas with high ODC activity. These results indicate that DFMO suppresses the outgrowth but not the initiation of UV-induced tumors. The DFMO treatment reduced the tumor load but did not offer the Xpa knockout mice full protection against UV carcinogenesis.
