Heteromorphic Chromosomes Research Articles

A De Novo Case of Floating Chromosomal Polymorphisms by Translocation in Quasipaa boulengeri (Anura, Dicroglossidae)

Very few natural polymorphisms involving interchromosomal reciprocal translocations are known in amphibians even in vertebrates. In this study, thirty three populations, including 471 individuals of the spiny frog Quasipaa boulengeri, were karyotypically examined using Giemsa stain or FISH. Five different karyomorphs were observed. The observed heteromorphism was autosomal but not sex-related, as the same heteromorphic chromosomes were found both in males and females. Our results indicated that the variant karyotypes resulted from a mutual interchange occurring between chromosomes 1 and 6. The occurrence of a nearly whole-arm translocation between chromosome no. 1 and no. 6 gave rise to a high frequency of alternate segregation and probably resulted in the maintenance of the translocation polymorphisms in a few populations. The translocation polymorphism is explained by different frequencies of segregation modes of the translocation heterozygote during meiosis. Theoretically, nine karyomorphs should be investigated, however, four expected karyotypes were not found. The absent karyomorphs may result from recessive lethal mutations, position effects, duplications and deficiencies. The phylogenetic inference proved that all populations of Q. boulengeri grouped into a monophyletic clade. The mutual translocation likely evolved just once in this species and the dispersal of the one karyomorph (type IV) can explain the chromosomal variations among populations.

Chromosome diversity analysis in various species of Vigna Savi from India

Wild species of Vigna are known to exhibit great range of phenotypic and genotypic diversity leading to development of several varieties and cultivars. However information regarding their chromosome biology is by and large lacking. The present study deals with karyotypic analysis in 10 taxa belonging to the genus Vigna. The details of chromosome morphology, karyotype formulae and symmetry index have been investigated. Heteromorphic chromosome pairs observed in two species viz. V. aconitifolia and V. radiata var. setulosa and NOR are also being reported in two taxa viz. V. mungo var. silvestris and V. sublobata. The karyomorphological studies confirmed that the asymmetry index of different taxa presently investigated had shown significant variation. The influence of karyotypic variation on genome evolution has been discussed in detail.

Evidence of karyotypic stasis during the evolutionary divergence between Paralabrax maculatofasciatus and P. nebulifer (Perciformes: Serranidae)

Information on chromosome structure is basic within the biological knowledge of any speciesand fundamental to the understanding of the cytogenetic phenomena underlying physiological, ontogenic and evolutionary processes. Knowledge on the degree of similarity of chromosomes in phylogenetically close species supplements the necessary information to raise causal hypotheses on the processes of evolutionary divergence.The objective of this study was to determine the cytogenetic similarity between Paralabrax maculatofasciatus and P. nebulifer, closely (phylogenetically) related species distributed in the Eastern Pacific, by comparing number, type and size of chromosomes of these taxa. The examination of mitotic cells from eleutheroembryos of both species showed a karyotype consisting of 48 acrocentric chromosomes (2n = 48A; fundamental number = 48), without the presence of heteromorphic chromosomes. No significant differences between species were observed in size and relative length (RL) of homeologous chromosome pairs which showed maximum and minimum values of 4 µm (RL = 5.5 %; pair 1) and 1.7 µm (RL = 2.3 %; pair 24), respectively. This karyotype is considered ancestral within the Order Perciformes and is present in most of the species of the Family Serranidae. The results found in this study supported the hypothesis that evolutionary divergence between P. maculatofasciatus and P.nebulifer occurred through the establishment of pre-mating reproductive barriers, without karyotype modification or formation of post-mating barriers, either pre-zygotic or post-zygotic.

Cyto-morphological and molecular characterization of Cajanus cajan × C. scarabaeoides F1 hybrid

Cajanus scarabaeoides has many desirable agro- nomic traits that deserve attention for introgression into pigeonpea cultivars. An inter-specific F1 hybrid was raised using C. cajan (ICP-26) as seed parent and C. scara- baeoides (ICPW-94) as pollen parent. Hybridity of the F1 plant was affirmed by analyzing the morphological attrib- utes, such as seed coat color, leaf shape, brown striations in the petal, pod features, and intermediate branching type etc. Most of the pollen mother cells (PMC) in the F1 hybrid have shown regular meiosis, but in some PMCs chromosome heteromorphism was observed for two pairs of bivalents during diakinesis, leading to precocious separation of biva- lents (62.81 %) at metaphase-I, and bridge formation (7.44 %) and laggards (2.48 %) at anaphase-I. SDS-PAGE of two major seed protein fractions (albumin and globulin) detected five polypeptide bands (Mol wt. 40.7, 39.8, 32.4, 23.5 and 19.5 KDa) unique to C. scarabaeoides, the male parent, in the F1 hybrids that evidenced the hybridity of F1 plants. Further, RAPD and ISSR marker analysis revealed the hybrid nature of the putative F1 plant. These analyses showed the inheritance of 28 RAPD and 12 ISSR markers, unique to C. scarabaeoides - the pollen parent, to F1 hybrids. This complementary use of cyto-morphological analysis, and molecular marker based genotyping allowed precise evaluation of the C. cajan×C. scarabaeoides inter- specific hybrid.

Impact of Chromosomal Heteromorphisms on Recurrent Miscarriages

Introduction: Chromosomal Heteromorphisms are the inherited variations at specific chromosomal regions without a proven impact on the phenotype of an individual. Material and Methods: We studied and compared the chromosome Heteromorphisms in the Karyotypes of two groups. The first group consisted of 320 individuals of 160 couples with more than two miscarriages and no live birth and the second group consisted of 412 individuals of 206 normal couples with more than 1 normal child birth. Results and discussion: Twenty Nine individuals (9.06%) with a history of recurrent pregnancy loss were found to have chromosomal heteromorphisms, whereas thirteen individuals (3.1%) from the normal group were having the chromosomal heteromorphism. The difference between the two groups was statistically significant (p<0.0001) Conclusion: These results are consistent with other similar studies that suggest the yet undefined relationship between chromosome heteromorphism and recurrent pregnancy loss.

Chromosome heteromorphisms are more frequent in couples with recurrent abortions

Chromosomal heteromorphism is considered a variant of a normal karyotype, but it is more frequent in couples with repeated miscarriages. We investigated chromosomal heteromorphism in couples with repeated miscarriages in comparison with a control group. A total of 455 couples who applied to our genetic diagnosis laboratory in Diyarbakir, Turkey, were evaluated for chromosome heteromorphisms; 221 of these couples (the study group) had recurrent abortions and 234 of them (the control group) had no history of abortions and had at least one living child. The patient group of couples with recurrent abortions were found to have a significantly higher rate of chromosome heteromorphism (8.4%) in comparison with the control group (4.9%). When the patients were evaluated according to gender, males had a significantly higher rate of chromosome heteromorphism (11.3%) than females (5.4%). We conclude that since couples with recurrent abortion and males have higher rate of chromosome heteromorphism, cases of heteromorphism should not be disregarded in the etiological investigation of recurrent abortions. Further research should be done to investigate the phenotypic effects of chromosome heteromorphism.

Comparative cytogenetics of two of the smallest Amazonian fishes: Fluviphylax simplex Costa, 1996 and Fluviphylax zonatus Costa, 1996 (Cyprinodontiformes, Poeciliidae)

The genus Fluviphylax Whitley, 1965is comprized of five valid species (Fluviphylax pygmaeus Myers et Carvalho, 1955, Fluviphylax zonatus, Fluviphylax simplex, Fluviphylax obscurus Costa, 1996,and Fluviphylax palikur Costa et Le Bail, 1999), which are endemic to the Amazon region. These fishes are the smallest known South American vertebrates and among the smallest know vertebrates on Earth. All species but the type Fluviphylax pygmaeus have been described in late 1990’s, and much remains unknown about the biology, taxonomy and systematics of this group of fishes. The aims of the present study were to establish the diploid and haploid number of Fluviphylax zonatus and Fluviphylax simplex, and to find species-specific markers for the discrimination of taxa. The diploid number for both species was 48 chromosomes, with no sex chromosome heteromorphism. Fluviphylax zonatus exhibited the karyotypic formula 4m+8sm+22st+14a and FN=82, and Fluviphylax simplex exhibited 4m+16sm+18st+10a and FN=86. The determination of the total mean length of the chromosomes and their grouping into five size classes demonstrated different chromosome composition of the two species. This difference was further supported by the distribution of constitutive heterochromatin. The meiotic analysis revealed 24 bivalents in both species, but Fluviphylax zonatus exhibited chromosomes with late pairing of the telomeric portions in the pachytene. These data reveal that cytogenetic characterization is useful and important for the discrimination of these species. Our study further indicates that this method could be employed in the analysis of other species of small fishes that are difficult to distinguish using traditional morphological traits or are morphologically cryptic.

Chromosome polymorphism in Rineloricaria pentamaculata (Loricariidae, Siluriformes) of the Paraná River basin

Cytogenetic analysis in three Rineloricaria pentamaculata populations revealed diploid number 2n = 56 chromosomes, karyotype formula 8m/sm + 48st/a and FN = 64. Owing to the presence of the heteromorphic chromosome pair with a big submetacentric chromosome and a small acrocentric one in both males and females, 42.9% of specimens in the Taua Stream population had the karyotype formula 9m/sm + 47st/a and FN = 65. Analysis of the nucleolus-organizing region by Ag-NOR and FISH techniques showed a single NOR system at pair 5 for R. pentamaculata populations of the Keller River and the Taua Stream. However, specimens of populations of the Tatupeba Stream had multiple NOR systems at pairs 5 and 8. A constitutive heterochromatin pattern in R. pentamaculata is mainly distributed in the pericentromeric and telomeric regions with interstitial markers in certain chromosomes. Heterochromatin is located in the telomeric and centromeric positions of the acrocentric chromosome in the heteromorphic pair of the Taua Stream population. In the submetacentric chromosome the markings are located in the telomeric (short arm), pericentomeric and interstitial (long arm) positions. The origins of polymorphisms are discussed.

Is Allium roylei Stearn still evolving through multiple interchanges?

An accession of A. roylei (2n = 16) procured from Gourwan district Udhampur of Jammu and Kashmir, India was studied for cytological details. Complex associations involving 4–16 chromosomes were observed in cells at diplotene and metaphase-I of meiosis. The anaphase-I segregations, however, were normal (8:8). Pollen stainability was high. Karyotypic studies, besides revealing heteromorphicity in chromosome pairs, also showed considerable differences in other quantitative parameters. Since frequency and type of chromosome associations during meiosis outnumber the number of heteromorphic chromosome pairs, interchanges involving small size or equal segments seem to have given rise to this cytotype of A. roylei.

Chromosomal markers in Parodontidae: an analysis of new and reviewed data with phylogenetic inferences

The taxonomy of the family Parodontidae is confused, with many open questions regarding the most appropriate generic groupings. Studies on the organization, structure, composition, and in situ location of chromosomal features have led to consistent advances in the understanding of genome evolution. Among the species of Parodontidae, the consistent chromosomal divergences can be helpful in taxonomic classification, such as heteromorphic chromosome sex, karyotypic formulae, and number/location of the repetitive DNAs. Molecular analysis of repetitive sequences of satellite DNA and their physical mapping in the chromosomes of different species in a single group may be used to infer evolutionary divergence and cladistic grouping. In the present study, rDNA and the satellite DNA pPh2004 were mapped by fluorescent in situ hybridization on the chromosomes of some species of Parodontidae. These results were analyzed and reviewed together with other chromosomal markers and previously published data, to formulate inferences about the diversification of the genomes and propose a clustering of some Parodontidae species. This analysis indicated that the species Apareiodon affinis, Parodon moreirai, Parodon hilarii, Parodon nasus, and Parodon pongoensis have an apomorphic state for satellite DNA pPh2004 in Parodontidae in relation to previously studied species of Apareiodon.

Giemsa staining and fluorescent chromosome banding in someVitisL. species

Giemsa staining technique and fl uorescent chromosome banding with CMA 3 and DAPI were applied to the mitotic chromosomes of Vitis champinii, V. cinerea, V. girdiana, V. labrusca, V. rotundifolia, V. rupestris and V. vinifera for the purpose of chromosome measurement and constitutive heterochromatin characterization at the cytochemical level, respectively. Both fl uorescent CMA and conventional Giemsa staining constituted a valuable tool for chromosome characterization. Karyomorphometric data obtained after Giemsa staining allowed for an average ideogram and karyotype formulae based on chromosome length for the species. V. champinii and V. girdiana distinguished from the other fi ve species by means of the total haploid chromosome length, by the longest chromosome length and by the average chromosome length. The seven grape species have moderate chromosome asymmetry values and were classifi ed on 2A Stebbins' category. Positive CMA bands were seen in all species. V. girdiana distinguished from the other species solely by the presence of two CMA + bands, while V. champinii, V. cinerea, V. labrusca, V. rotundifolia and V. rupestris had four bands. V. vinifera showed chromosome heteromorphism for CMA bands. No clearly visible DAPI + band was seen in the species. According to the present observations, it seems that the evolutionary process of speciation involving North American and European Euvitis species studied, resulted in some discrete changes in chromosome measurements and also in heterochromatin base composition of at least one species. These data enlarge the chromosomal information of the genus Vitis and make possible further comparative studies into the Vitaceae family.

Cytogenetic, Molecular-Cytogenetic, and Clinical-Genealogical Studies of the Mothers of Children with Autism: A Search for Familial Genetic Markers for Autistic Disorders

State-of-the-art cytogenetic and molecular-cytogenetic methods for studying human chromosomes were used to analyze chromosomal anomalies and variants in mothers of children with autistic disorders and the results were compared with clinical-genealogical data. These investigations showed that these mothers, as compared with a control group, showed increases in the frequencies of chromosomal anomalies (mainly mosaic forms involving chromosome X) and chromosomal heteromorphisms. Analysis of correlations of genotypes and phenotypes revealed increases in the frequencies of cognitive impairments and spontaneous abortions in the mothers of children with autism with chromosomal anomalies, as well as increases in the frequencies of mental retardation, death in childhood, and impairments to reproductive function in the pedigrees of these women. There was a high incidence of developmental anomalies in the pedigrees of mothers with chromosomal variants. These results lead to the conclusion that cytogenetic and molecular-cytogenetic studies of mothers and children with autism should be regarded as obligatory in terms of detecting possible genetic causes of autism and for genetic counseling of families with autistic children.

Meiotic behavior of Carica papaya and Vasconcellea monoica

Carica papaya L. and Vasconcellea monoica, cultivated and wild forms, respectively, belong to Cari- caceae family and have 2n = 18 chromosomes. The objectives of the present work were to evaluate the meiosis and the pollen viability in both species. Floral buds in different development stages were collected in 3:1 etha- nol/acetic acid and put into the freezer until their utilization. Anthers were squashed on slides, stained with 1% acetic carmine and covered with cover glasses. The slides were sealed and observed under optical microscope. The meiotic analyses confi rmed that both species are diploids, with 2n = 2x = 18 chromosomes and 9 bivalents at diakinesis. Abnormalities were observed in different meiotic stages, in both species although they were higher in V. monoica. This fact could be explained by the presence of sticky chromosomes in V. monoica, which resulted in an irregular segregation during the anaphase I and contributed to produce unbalanced cells and consequently, irregular meiotic products. In C. papaya and V. monoica lag chromosomes were observed. The meiotic index and pollen viability were higher in C. papaya than in V. monoica: 94.84 and 96.0% against 77.57 and 70.93%, respectively. These data suggest that V. monoica is a meiotic unstable species with low pollen viability. Therefore, this species can be problematic when involved in hybridization methodologies. No unpaired chromosomes were observed in Carica papaya. Thus, there is no evidence of sexual heteromorphic chromosomes.

Cytotaxonomy and DNA taxonomy of lizards (Squamata, Sauria) from a tropical dry forest in the Chamela-Cuixmala Biosphere Reserve on the coast of Jalisco, Mexico

Tropical dry forests contribute to a substantial proportion of the herpetological diversity of Mexico. The south-western coast of Jalisco is one of the more important areas by number of endemics and the high presence of endangered and restricted species. In this paper we used a combined karyological and molecular genetic (sequences of mtDNA genes for NDH2, cytb or 16S rDNA) approach to genetically characterize 13 lizard species belonging to seven families that inhabit the dry forests of the Chamela-Cuixmala Biosphere Reserve (Anguidae: Gerrhonotus cf. liocephalus; Eublepharidae: Coleonyx elegans; Phyllodactylidae: Phyllodactylus lanei; Gekkonidae: Hemidactylus frenatus; Phrynosomatidae: Sceloporus melanorhinus, S. utiformis, Urosaurus bicarinatus; Polychrotidae: Norops nebulosus; Scincidae: Mabuya unimarginata, Plestiodon parvulus; Teiidae: Ameiva undulata, Aspidoscelis communis, A. lineattissima). The karyotypes of six species were here described for the first time (G. liocephalus, 2n = 38, 14 macrochromosomes and 24 microcromosomes; C. elegans, 2n = 24 FN = 26; N. nebulosus 2n = 30, 13 macroand 17 microchromosomes; M. unimarginata 2n = 32, 18 macroand 14 microchromosomes; P. parvulus 2n = 26, 12 macroand 14 microchromosomes; A. undulata 2n = 50, 26 macroand 24 microchromosomes). Chromosomal heteromorphism was found in C. elegans, N. nebulosus, and S. melanorhinus. For P. lanei we found a karyotype different from that previously described in other localities. This variation matched with a high genetic divergence usually found in different species. The DNA typing of mtDNA genes allowed the identification of the taxonomic affinities of five Mexican endemic species, namely: U. bicarinatus, A. nebulosus, P. parvulus, A. lineattissima and A. communis. The specimen of Gerrhonotus from Chamela is very divergent by 16S rDNA and probably does not belong to the so far studied species of Gerrhonotus. High genetic divergence has been also observed between samples of A. undulata and U. bicarinatus from different regions. In these latter two cases, additional data are needed to understand the taxonomic status of these populations.

Caracterización cariotípica en mitosis y meiosis del robalo blanco Centropomus undecimalis (Pisces: Centropomidae)

The common snook Centropomus undecimalis inhabits marine, brackish and freshwater habitats in the Western Central Atlantic Ocean, including the Gulf of Mexico. Common snook is an economically important fish in many localities, nevertheless the number of studies on its biology and genetics are still few. The present study attempts to establish the cytogenetic profiles of the specimens collected in Paraiso Municipality Tabasco, Mexico. Tissue of five females and eight male organisms were processed by conventional cytological techniques to obtain chromosome slides of high quality in order to assemble the karyotype. The results from the kidney tissue analysis showed that 85.1% of 288 mitosis had a 2n = 48 chromosomes, and 52.8% of 104 meiosis exhibited the haploid number 1n = 24. The diploid karyotype showed 48 monoarmed chromosomes of the telocentric (T) type. There was no chromosome heteromorphism between females and males. The diploid karyotype was very similar to that observed in the majority of marine fishes.

Chromosome analysis in Pseudopaludicola (Anura, Leiuperidae), with description of sex chromosomes XX/XY in P. saltica

Taxonomic changes have frequently occurred in the anuran genus Pseudopaludicola as a consequence of high morphological similarity among its species. The present work reports karyotypic analysis of three Pseudopaludicola species sampled in their type locality and four Pseudopaludicola populations from distinct localities, aiming at contributing to the systematics of this genus. Chromosomes were stained with Giemsa or submitted to the silver staining (Ag-NOR) and C-banding techniques. The karyotype was 2n=22 in P. mineira, Pseudopaludicola sp. and two populations of P. saltica. The chromosome pair 8 was heteromorphic in P. saltica, characterizing a XX/XY sex-determination system with telocentric X and submetacentric Y. Highly similar karyotypes with 2n=18 chromosomes were observed in P. canga, P. aff. canga from Barreirinhas, State of Maranhão, Uberlândia, State of Minas Gerais and Icém, State São Paulo. The high similarity among the karyotypes 2n=18 suggested that the populations of P. aff. canga belong to the group 'pusilla', the same group of P. canga. The data demonstrated also that P. aff. canga from Barreirinhas (northeast region) is cytogenetically identical to P. canga with regarding the NOR site position in pair 3 and the presence of a heterochromatic block in the pair 2, whereas P. aff. canga from Uberlândia and Icém (southeast) had the NOR in the pair 9. Moreover, the cytogenetic data discriminated P. mineira and Pseudopaludicola sp. from the previously analyzed species with 22 chromosomes, and suggested that Pseudopaludicola sp. is an undescribed species. Sexual heteromorphic chromosomes are firstly reported in Pseudopaludicola and the data indicated the need of an extensive taxonomic review in this genus.

Chromosome Evolution in the Lizard Genus Gekko (Gekkonidae, Squamata, Reptilia) in the East Asian Islands

The lizard genus Gekko consists of over 30 species distributed in Asia and Oceania. From the insular region of East Asia including Japan and Taiwan, 9 species (G. hokouensis, G. japonicus, G. shibatai, G. tawaensis, G. vertebralis,G. yakuensis, and 3 undescribed species) are currently recognized. We made karyological analyses for all these species. Their karyotypes invariably consisted of 2N = 38 chromosomes, but exhibited considerable variation in fundamental number (ranging from 56–62). Substantial chromosomal variation was detected even among populations of a morphologically relatively uniform species, G. hokouensis. Populations of G. hokouensis from the central and northern Ryukyus exhibited prominent female heteromorphic (i.e., ZW type) sex chromosomes. Populations of the southern Ryukyus exclusive of Yonagunijima also had ZW sex chromosomes, whose heteromorphisms were, however, much less prominent. The other G. hokouensis populations including the topotypic continental representatives and the population from Yonagunijima of the southern Ryukyus exhibited no sex chromosome heteromorphism at all. These results strongly suggest that G. hokouensis in the current taxonomic definition actually includes more than 2 species. The process of chromosomal evolution in the East Asian Gekko is hypothesized.

Familial 18 centromere variant resulting in difficulties in interpreting prenatal interphase FISH

We report here on a familial case of centromeric heteromorphism of chromosome 18 detected by prenatal interphase fluorescence in situ hybridization (FISH) analysis transmitted by the mother to her fetus, and resulting in complete loss of one 18 signal. The prenatal diagnosis was performed by interphase FISH (AneuVysion probe set, and LSI DiGeorge 22q11.2 kit) because of the presence of an isolated fetal cardiac abnormality, and was first difficult to interpret: only one centromeric 18 signal was detectable on prenatal interphase nuclei, along with one signal for the Y and one for the X chromosome. The LSI DiGeorge 22q11.2 kit also showed the absence of one TUPLE 1 signal on all examined nuclei. In fact, the FISH performed on maternal buccal smear displayed the same absence of one chromosome 18 centromeric signal, combined with the presence of two TUPLE1 signals. All these results led to the diagnosis of an isolated 22q11.2 fetal microdeletion that was confirmed on metaphases spreads. This case illustrates once again that the locus specific (LSI) probes are more effective than the alpha centromeric probes for interphase analysis. The development of high-quality LSI probes for chromosomes 18, X and Y could avoid the misinterpretation of prenatal interphase FISH leading to numerous additional and expensive investigations.

Chromosome Evolution and Diversification in North American Spiny Lizards (Genus Sceloporus)

The genus Sceloporus is a diverse clade of lizards that exhibits substantial variation in chromosome numbers and sex chromosome heteromorphisms, 2 features of the genome that are static among most other pleurodont iguanian lizards. Evolutionary changes to the fundamental number of chromosomes are hypothesized to be a primary factor responsible for driving the diversification of Sceloporus. We explore the patterns of chromosome evolution in Sceloporus using a combination of ancestral state estimations and species diversification tests. Phylogenetic relationships and divergence times within Sceloporus (53 species representing all 19 species groups) are estimated using 4 nuclear genes (>3.3 kb) and relaxed-clock analyses that incorporate a fossil calibration on the root of the tree. We test the hypothesis that chromosome evolution is correlated with shifts in species diversification using cross-validation predictive densities, a new Bayesian approach for modeling the number of species that are predicted to have evolved in the absence of a certain historical event (e.g., a change in chromosome numbers). Results of the cross-validation predictive densities approach indicate that chromosomal evolution is correlated with significantly higher species diversity than predicted under the background rate of diversification in Sceloporus. We conclude by discussing the future of comparative cytogenetic investigations in Sceloporus.

Tekrarlayan Gebelik Kaybı Olan Çiftlerde Yapısal Kromozom Bozuklukları

Objective: Recurrent pregnancy loss is an important problem affecting couples trying to conceive. Genetic factors, particularly chromosomal abnormalities appear to be highly associated with reproductive loss. The frequency of presence of at least one partner, who is a carrier of a structural chromosome rearrangement, varies from 3% to 11% among couples with a history of recurrent pregnancy loss. The aim of this study was to introduce the cytogenetic data of couples that referred with recurrent pregnancy loss to our center. Material and Methods: Chromosome analyses were performed in 449 couples with more than one pregnancy loss using GTL banding. Results: Chromosome abnormalities were detected in one partner in 19 of 449 couples. All chromosome abnormalities were structural, and 18 of them were balanced. Autosomal reciprocal translocations were the most frequent type (2.9%) of abnormalities. The unique Robertsonian translocation found in our study was t(13;14), which was observed in two patients. Chromosomal heteromorphisms were determined in 19.59% of patients. Conclusion: The frequency of chromosomal abnormalities were found as 4.23% in our series. Cytogenetic investigation of couples with recurrent pregnancy loss is necessary as chromosomal abnormalities constitute a very important part of factors that cause pregnancy loss.