Florina Raicu

Male infertility: role of genetic background.

Male infertility represents one of the clearest examples of a complex disease with a substantial genetic basis. Numerous male mouse models, mutation screening and association studies reported over the last few years reveal the high prevalence of genetic causes of spermatogenic impairment, accounting for 10-15% of severe male infertility, including chromosomal aberrations and single gene mutations. Natural selection prevents the transmission of mutations causing infertility, but this protective mechanism may be overcome by assisted reproduction techniques. Consequently, the identification of genetic factors is important for appropriate management of the infertile couple. However, a large proportion of infertile males are diagnosed as idiopathic, reflecting poor understanding of the basic mechanisms regulating spermatogenesis and sperm function. Furthermore, the molecular mechanisms underlying spermatogenic damage in cases of genetic infertility (for example Yq microdeletions) are not known. These problems can be addressed only by large scale association studies and testicular or spermatozoal expression studies in well-defined alterations of spermatogenesis. It is conceivable that these studies will have important diagnostic and therapeutic implications in the future. This review discusses the genetic causes of male infertility known to date, the genetic polymorphisms possibly associated with male infertility, and reports novel results of global gene expression profiling of normal human testis by microarray technology.

Genotype-Phenotype Correlations in a Mountain Population Community with High Prevalence of Wilson’s Disease: Genetic and Clinical Homogeneity

Wilson’s disease is an autosomal recessive disorder caused by more than 500 mutations in ATP7B gene presenting considerably clinical manifestations heterogeneity even in patients with a particular mutation. Previous findings suggested a potential role of additional genetic modifiers and environment factors on phenotypic expression among the affected patients. We conducted clinical and genetic investigations to perform genotype-phenotype correlation in two large families living in a socio-culturally isolated community with the highest prevalence of Wilson’s disease ever reported of 1∶1130. Sequencing of ATP7B gene in seven affected individuals and 43 family members identified a common compound heterozygous genotype, H1069Q/M769H-fs, in five symptomatic and two asymptomatic patients and detected the presence of two out of seven identified single nucleotide polymorphisms in all affected patients. Symptomatic patients had similar clinical phenotype and age at onset (18±1 years) showing dysarthria and dysphagia as common clinical features at the time of diagnosis. Moreover, all symptomatic patients presented Kayser-Fleischer rings and lack of dystonia accompanied by unfavourable clinical outcomes. Our findings add value for understanding of genotype-phenotype correlations in Wilson’s disease based on a multifamily study in an isolated population with high extent of genetic and environmental homogeneity as opposed to majority of reports. We observed an equal influence of presumed other genetic modifiers and environmental factors on clinical presentation and age at onset of Wilson’s disease in patients with a particular genotype. These data provide valuable inferences that could be applied for predicting clinical management in asymptomatic patients in such communities.

Paleo-Balkan and Slavic Contributions to the Genetic Pool of Moldavians: Insights from the Y Chromosome

Moldova has a rich historical and cultural heritage, which may be reflected in the current genetic makeup of its population. To date, no comprehensive studies exist about the population genetic structure of modern Moldavians. To bridge this gap with respect to paternal lineages, we analyzed 37 binary and 17 multiallelic (STRs) polymorphisms on the non-recombining portion of the Y chromosome in 125 Moldavian males. In addition, 53 Ukrainians from eastern Moldova and 54 Romanians from the neighboring eastern Romania were typed using the same set of markers. In Moldavians, 19 Y chromosome haplogroups were identified, the most common being I-M423 (20.8%), R-M17* (17.6%), R-M458 (12.8%), E-v13 (8.8%), R-M269* and R-M412* (both 7.2%). In Romanians, 14 haplogroups were found including I-M423 (40.7%), R-M17* (16.7%), R-M405 (7.4%), E-v13 and R-M412* (both 5.6%). In Ukrainians, 13 haplogroups were identified including R-M17 (34.0%), I-M423 (20.8%), R-M269* (9.4%), N-M178, R-M458 and R-M73 (each 5.7%). Our results show that a significant majority of the Moldavian paternal gene pool belongs to eastern/central European and Balkan/eastern Mediterranean Y lineages. Phylogenetic and AMOVA analyses based on Y-STR loci also revealed that Moldavians are close to both eastern/central European and Balkan-Carpathian populations. The data correlate well with historical accounts and geographical location of the region and thus allow to hypothesize that extant Moldavian paternal genetic lineages arose from extensive recent admixture between genetically autochthonous populations of the Balkan-Carpathian zone and neighboring Slavic groups.

Genetic affinities among the historical provinces of Romania and Central Europe as revealed by an mtDNA analysis

BackgroundAs a major crossroads between Asia and Europe, Romania has experienced continuous migration and invasion episodes. The precise routes may have been shaped by the topology of the territory and had diverse impacts on the genetic structure of mitochondrial DNA (mtDNA) in historical Romanian provinces. We studied 714 Romanians from all historical provinces, Wallachia, Dobrudja, Moldavia, and Transylvania, by analyzing the mtDNA control region and coding markers to encompass the complete landscape of mtDNA haplogroups.ResultsWe observed a homogenous distribution of the majority of haplogroups among the Romanian provinces and a clear association with the European populations. A principal component analysis and multidimensional scaling analysis supported the genetic similarity of the Wallachia, Moldavia, and Dobrudja groups with the Balkans, while the Transylvania population was closely related to Central European groups. These findings could be explained by the topology of the Romanian territory, where the Carpathian Arch played an important role in migration patterns. Signals of Asian maternal lineages were observed in all Romanian historical provinces, indicating gene flow along the migration routes through East Asia and Europe.ConclusionsOur current findings based on the mtDNA analysis of populations in historical provinces of Romania suggest similarity between populations in Transylvania and Central Europe, supported both by the observed clines in haplogroup frequencies for several European and Asian maternal lineages and MDS analyses.

Mitochondrial DNA haplogroup K as a contributor to protection against thyroid cancer in a population from southeast Europe

We aimed to analyze the contribution of mitochondrial DNA (mtDNA) haplogroups of the mtDNA control region to thyroid cancer risk in a population from southeastern Europe consisting of 235 thyroid tumor patients, including 114 patients with thyroid follicular adenoma, 121 patients with papillary thyroid carcinoma, and 419 healthy controls. Binary logistic regression with adjustment for age and gender revealed that mtDNA haplogroup K was significantly associated with a protective role for thyroid cancer in the combined tumor group versus controls. These results indicate a potential role for mtDNA haplogroups as important candidate susceptibility markers for the patients with thyroid nodules.

Multiplex PCR for the assignment of some major branches of the Y chromosome tree

In this paper we describe a multiplex PCR useful to as-sign some major Y chromosome tree branches (DE, G2, I, J and J2) (for the nomenclature of the Y chromosome tree branches, see YCC 2002). These are prev alent in all Southern European populations, accoun ting between 51% and 77% of the total male population (Di Giacomo et al. 2003 and personal data). The identification of the allelic state at every locus in the study is done either directly (presence/a bsenc e of the specific PCR fragment), or can be simply obtained with further sequential steps of dot-blot hybrid ization with specific probes. In the last years a large number of single nucleotide polymorphic (SNP) binary markers have been identified in the non-recombining portion of the human Y chrom o-some (NRY) (YCC 2002). SNPs are ideal genetic mar k-ers for med ical and population genetic studie s, since they are widespread in the human genome and are easily de-tected by PCR based methods. In general, the SNPs ex-hibit only two, evolutionarily stable, alleles. This ad van t-age is often counterbalanced by the necessity of typing large numbers of them in many individuals. Genotyping for these markers is of great importance in forensics and in association studies. Moreover, since the NRY lacks genetic recombination during meioses, it is a pow erful tool in phylogenetic studies. In order to increase the pro-ductivity of such studies, the first choice will be to study simultaneously more SNPs in a single multiplex PCR reaction. Two papers concerning the use of mult iplex PCR in the study of the human Y chromosome SNP variation have been published recently. One of them uses a mini-sequencing/capillary electrophoresis method for Y chro-mosome typing in forensic studies (Sanchez et al. 2003); the other one uses a primer extension/mass spectroscopy method for high throughput SNP genotyping of the Y chromosome (Paracchini et al. 2002). The method pre-sented here provides a reliable effort-effective, time-effec -tive and cost-effective method for the early stages of human Y chromosome genotyping, being particularly useful when little information or no information at all is available about the genetic structure of the population under study.