C-polymorphism of chromosomes 1, 9, 16 and Y in newborn infants of various gestational ages

Comparative evaluation of absolute C-segment lengths of chromosomes 1, 9, 16 and Y in new-born children of different gestational age has revealed no significant differences in their value between individuals with unfinished intrauterine development and those born in time.     

Molecular screening for Yq microdeletion in men with idiopathic oligozoospermia and azoospermia

Infertility affects 15% couples attempting pregnancy and in 40–50% of these cases the male partner has qualitative or quantitative abnormalities of sperm production. Microdeletions in the azoospermia factor (AZF) region on the long arm of the Y chromosome are known to be associated with spermatogenic failure and have been used to define three regions on Yq (AZFa, AZFb and AZFc) which are critical for spermatogenesis and are recurrently deleted in infertile males. Semen analysis was carried out on one hundred and twenty five infertile males with oligozoospermia and azoospermia. Cytogenetic analysis was done for all the cases and in all cytogenetically normal cases (n = 83) microdeletion analysis was carried out on DNA extracted from peripheral blood using PCR. The sequence tagged sites (STS) primers sY84, sY86 (AZFa); sY127, sY134 (AZFb); sY254, sY255 (AZFc) were used for each case. Eight of the eighty three cases (9.63%) showed deletion of at least one of the STS markers. Correlation of phenotype with microdeletion was done in each case to determine any phenotype association with deletion of particular AZF locus. Based on the present study, the frequency of microdeletion in the Indian population is 9.63%. This study emphasizes the need for PCR analysis for determining genetic aetiology in cases with idiopathic severe testiculopathy.     

Effect of thyrotrophin-releasing hormone on serum prolactin levels in men with azoospermia.

Infertile men with azoospermia and low testosterone levels because of Klinefelter's or Sertoli cell-only syndrome responded to a single injection of TRH by an increase in serum prolactin levels. The degree of this response was not as great as in fertile men with normospermia and normal testosterone levels, although initial prolactin levels had been similar in both groups. The results demonstrate a link between testosterone and prolactin levels in fertile and infertile men.     

Hormone levels in serum and seminal plasma of men with different types of azoospermia

Hormone concentrations in the serum and seminal plasma of 15 normozoospermic, 17 excretory azoospermic and 14 secretory azoospermic men were measured. The results indicate that: (a) serum FSH and LH levels are markedly elevated in secretory azoospermia, as compared with excretory azoospermia and normozoospermia; (b) serum 17 alpha-hydroxyprogesterone levels are somewhat raised in secretory azoospermia as compared with excretory azoospermia and normozoospermia; (c) serum testosterone levels are lower in both types of azoospermia with respect to normozoospermia; (d) in secretory azoospermia the oestradiol serum levels are relatively high and dihydrotestosterone serum levels relatively low, whereas the serum levels of these hormones in excretory azoospermia are similar to those in normozoospermic men; (e) in the seminal plasma of azoospermic patients the levels of prolactin, progesterone, testosterone, dihydrotestosterone and oestradiol were depressed, but only dihydrotestosterone levels could be of value in differentiating types of azoospermia because they are lower in secretory azoospermia. We suggest that the measurement of FSH, LH, 17 alpha-hydroxyprogesterone, dihydrotestosterone and oestradiol in serum and dihydrotestosterone in seminal plasma may be used in the differential diagnosis between secretory and excretory azoospermia when invasive tests are unavailable.     

Cytogenetic abnormalities in 222 infertile men with azoospermia and oligospermia in Iran: Report and review

BACKGROUND:

Infertility affects approximately 10%-15% of couples in reproductive age. In half of the couples, causes are male-related, associated with impaired spermatogenesis. There is a complex correlation between genetics and infertility. Several factors affect on gametogenesis, from which factors that lead to chromosomal abnormalities are one of the best known. The aim of this study was to determine type and rate of chromosomal abnormalities in infertile azoospermic and oligospermic males in Iranian population.

MATERIALS AND METHODS:

The records of a total of 222 participants were evaluated retrospectively.

RESULTS:

As a whole we observed 13.96% chromosomal abnormality, from which 12.15% showed numerical and 1.8% showed structural abnormalities.

CONCLUSION:

Comparison of our results with the review of the literature shows a higher incidence (4- fold) of gonosomal, in particular, numerical gonosomal, chromosomal anomalies. Cytogenetic analysis is strongly suggested for infertile men, particularly in those who suffer from azoospermia.     

Increased frequency of CFTR gene mutations identified in Indian infertile men with non-CBAVD obstructive azoospermia and spermatogenic failure

High incidence of mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene is associated with congenital bilateral absence of the vas deferens (CBAVD) and is considered as the genital form of cystic fibrosis (CF). The CFTR gene may also be involved in the etiology of male infertility in cases other than CBAVD. The present study was conducted to identify the spectrum and frequency of CFTR gene mutations in infertile Indian males with non-CBAVD obstructive azoospermia (n = 60) and spermatogenic failure (n = 150). Conspicuously higher frequency of heterozygote F508del mutation was detected in infertile males with non-CBAVD obstructive azoospermia (11.6%) and spermatogenic failure (7.3%). Homozygous IVS(8)-5T allele frequency was also significantly higher in both groups in comparison to those in normal healthy individuals. Two mutations in exon 25 viz., R1358I and K1351R were identified as novel mutations in patients with non-CBAVD obstructive azoospermia. Mutation R1358I was predicted as probably damaging CFTR mutation. This is the first report from the Indian population, emphasizing increased frequency of CFTR gene mutations in male infertility other than CBAVD. Thus, it is suggested that screening of CFTR gene mutations may be required in infertile Indian males with other forms of infertility apart from CBAVD and willing for assisted reproduction technology.     

Rapid detection of sex chromosomal aneuploidies by QF-PCR: application in 200 men with severe oligozoospermia or azoospermia

Klinefelter syndrome is the most common genetic cause of severe male factor infertility. Cytogenetic evaluation of metaphase chromosomes generally has a long turnaround time. We describe a reliable molecular genetic method that can be completed in 2 working days to identify the presence of any extra X chromosomes. The quantitative fluorescent (QF) 5-plex PCR includes the amplification of amelogenin, which is present on both sex chromosomes in a biallelic form, a polymorphic short tandem repeat (STR) on the pseudoautosomal region of X and Y (X22), two polymorphic X-specific STRs (DXS6803, DXS6809), and a Y-specific marker (SY134), in a single tube. The presence of an extra X chromosome is recognized either by a supernumerary peak or an increased peak area based on criteria we have developed. The application of the method on 200 patients resulted in the identification of 14 patients (7%) with Klinefelter syndrome or a variant form (2 SRY-positive 46,XX men), as well as an additional patient with 47,XYY karyotype. The QF-PCR method, along with Y chromosome microdeletion testing, can be used as a first-step genetic analysis in azoospermic or severely oligozoospermic patients for the rapid identification of sex chromosome aneuploidies.     

Meiotic studies of infertile men in case of non-obstructive azoospermia with normal karyotype and no microdeleted Y-chromosome precise the clinical couple management

To identify meiotic criteria for infertility management in non-obstructive azoospermic men, a prospective and multicentric study was organized in Andrological Departments of Paris (France), Roma (Italy) and Budapest (Hungary). In 117 non-obstructive azoospermic men with normal karyotype and no Y-chromosome microdeletion, histology and meiotic studies on bilateral bipolar testicular biopsies were done. Histologically, 40 patients (34%) presented spermatocyte or spermatid arrest, 39 (33%) hypospermatogenesis whereas no meiotic cell could be observed in the remaining patients (33%). Cytogenetically, meiotic figures could only be obtained from the two first histological groups. Meiotic abnormalities were observed in a total of 44 patients (37.6%) including nine patients (7.7%) with severe class I and class IIB anomalies and 19 patients (16.2%) with class IIC environmentally linked meiotic abnormalities. These results provided essential clues for an accurate clinical management. For patients with no meiotic figures and patients with class I and class IIB anomalies, an hormonal stimulation is illusory and a sperm gift should be directly proposed. An hormonal stimulation should be proposed to all the other patients, either directly or following the treatment of the testicular microenvironment for the patients presenting class IIC anomalies. The genetic risk and possibility of prenatal chromosomal analysis in case of pregnancy should be clearly exposed to all the couples in all the cases where type IIA, III or IV anomalies are present. This therapeutical strategy has been applied to all the patients in our series.     

Altered microRNA expression in patients with non-obstructive azoospermia

Background  

MicroRNAs (miRNAs), a class of small non-coding RNA molecules, are indicated to play essential roles in spermatogenesis. However, little is known about the expression patterns or function of miRNAs in human testes involved in infertility.     

Chromosome anomalies in human azoospermia

The anomalies of genome were found as a result of cytogenetic study of three azoospermic men. In two cases, the circular Y chromosome was revealed. Different methods of chromosome staining demonstrated complete loss of heterochromatic portion of the long arm of the Y chromosome in one case, and the absence of the euchromatic region in another. A balanced translocation among the chromosomes 1 and 15 was observed in the third case. A question concerning disturbances of spermatogenesis having chromosomal etiology is discussed.     

A family of human Y chromosomes has dispersed throughout northern Eurasia despite a 1.8-Mb deletion in the azoospermia factor c region

The human Y chromosome is replete with amplicons-very large, nearly identical repeats-which render it susceptible to interstitial deletions that often cause spermatogenic failure. Here we describe a recurrent, 1.8-Mb deletion that removes half of the azoospermia factor c (AZFc) region, including 12 members of eight testis-specific gene families. We show that this "b2/b3" deletion arose at least four times in human history-likely on inverted variants of the AZFc region that we find exist as common polymorphisms. We observed the b2/b3 deletion primarily in one family of closely related Y chromosomes-branch N in the Y-chromosome genealogy-in which all chromosomes carried the deletion. This branch is known to be widely distributed in northern Eurasia, accounts for the majority of Y chromosomes in some populations, and appears to be several thousand years old. The population-genetic success of the b2/b3 deletion is surprising, (i) because it removes half of AZFc and (ii) because the gr/gr deletion, which removes a similar set of testis-specific genes, predisposes to spermatogenic failure. Our present findings suggest either that the b2/b3 deletion has at most a modest effect on fitness or that, within branch N, its effect has been counterbalanced by another genetic, possibly Y-linked, factor.     

Interaction of B chromosomes with A or B chromosomes in segregation in insects

Additional or B chromosomes not belonging to the regular karyotype of a species are found in many animal and plant groups. They form a highly heterogeneous group with respect to their morphology and behaviour both in mitosis and meiosis. Achiasmatic mechanisms that ensure the segregation of a B chromosome from another B chromosome or from an A chromosome are reviewed. An achiasmatic mechanism characterized by the "distance pairing" of segregating univalents at metaphase I was found to be responsible for the preferential segregation of B chromosome univalents in Hemerobius marginatus L. (Neuroptera), and a mechanism characterized by the "touch and go pairing" of segregating univalents was responsible for the highly regular segregation of a B chromosome and the X chromosome in Rhinocola aceris (L.) (Psylloidea, Homoptera). The latter mechanism resulted in the integration of a B chromosome to the A chromosome set as a Y chromosome in a psyllid species Cacopsylla peregrina (Frst.). Furthermore, B chromosomes can disturb the regular segregation of the achiasmatic X and Y chromosomes resulting in the formation of X0/XY polymorphism in a population, which might precede the loss of the Y chromosome. The absence of observations on accurately functioning achiasmatic segregation mechanisms in grasshoppers (Orthoptera) was attributed to the X and B chromosomes, which re-orient one or several times during metaphase I. Apparently, these re-orientations mask any achiasmatic segregation mechanism that might operate during meiotic prophase in these insects.     

Cytogenetic relationship ofAegilops longissima chromosomes with common wheat chromosomes

The relationships of three wheat-Aegilops longissima chromosome addition lines A, C, and D with homoeologous wheat chromosomes were studied in PMC meiosis. Substitutions of alien chromosome A for wheat chromosome 6 B, chromosome C for 1 B and chromosome D for 4 B were obtained. The production of 4 BS/C and 7 BS/D chromosome translocations indicated cytogenetic relationships of C partially to homoeologous wheat chromosomes of group 1 and 4, and D partially to homoeologous wheat chromosomes of group 4 and 7.     

Chromosome abnormalities in spermatozoa of patients with azoospermia and normal somatic karyotype

Since epididymal and testicular spermatozoa of azoospermic patients are frequently used for intracytoplasmic sperm injection (ICSI), many studies have been carried out to evaluate their karyotype. This article will review all published data on this topic. In most of the studies, spermatozoa have been retrieved from the testis or the epididymis of patients with nonobstructive (NOA) or obstructive (OA) azoospermia, respectively. Sperm aneuploidy has been evaluated by fluorescence in situ hybridization using probes for sex chromosomes and an array of autosomes. A significantly higher sperm aneuploidy rate has been reported in patients with NOA and OA compared to ejaculated spermatozoa, mainly for sex chromosomes. The magnitude of the increase varies between studies, probably because of the heterogeneity of case selection as well as of the methodology employed. The majority of the studies reported that patients with NOA have a greater sperm aneuploidy rate compared to OA. The greater frequency of sperm aneuploidy in azoospermic patients increases the risk of transmitting a karyotype abnormality to the offspring generated by ICSI.     

Effects of age on segregation of the X and Y chromosomes in cultured lymphocytes from Chinese men

Chromosome malsegregation in binucleated lymphocytes is a useful endpoint to evaluate age effect on genetic stability. However, the investigations on chromosome malsegregation in binucleated lymphocytes from Chinese are scarce. In this study, peripheral blood lym- phocytes were collected from 14 old （60-70 years） and 10 young （22-26 years） healthy Chinese men. To detect malsegregation of the sex chromosomes, multi-color fluorescence in situ hybridization （FISH） was performed on binucleated lymphocytes, cytokinesis-blocked by cytochalasin B at the first mitosis after phytohaemagglutinin stimulation. Compared with that in young men, a significant increase in frequencies of loss of chromosome X （9.2± 3.2‰ vs. 1.1 ± 0.9‰, P 〈 0.001） and Y （2.5 ± 1.9‰ vs. 0.2± 0.3‰, P 〈 0.001） was found in old men. Similarly, nondisjunction of chromosome X （16.5± 3.4‰ vs. 3.5 ± 1.1‰, P 〈 0.001） and Y （7.2 ± 2.6‰ vs. 2.4 ± 1.3‰, P 〈 0.001） occurred more frequently in old men than in young men. Regardless of donor＇s age, nondisjunction is more prevalent than loss for both chromosome X and Y. The frequencies of observed simultaneous malsegregation were relatively higher than the expected, suggest- ing an association between malsegregation. These results indicated that in Chinese men, malsegregation of the sex chromosomes increases with age in an associated fashion, and nondisjunction accounts for the majority of spontaneous chromosome malsegregation.     

Mitosis with undivided chromosomes

Summary Cases of cell division with single chromatids are discussed in connection with a study on mitosis with undivided chromosomes made on living material of the endosperm of Haemanthus katharinae. Such divisions are known from certain abnormal mitoses in the microspores of a few plant species, and also from the second meiotic division, in which it is possible in numerous materials to study the behaviour of daughter univalents, and, in a few cases, also daughter chromosomes derived from chromosomes that were paired during the first division.The various cases of mitosis with single chromatids show a great variation with respect to the degree of scattering of the chromosomes over the spindle at metaphase. In a few cases there is practically no tendency to form a metaphase plate. In other cases the tendency to form such a plate is more or less pronounced, but also in these cases it is difficult for the chromosomes to form this arrangement. Some of them remain scattered over the spindle. After the metaphase a kind of anaphase usually follows in which the single chromatids, without division, move to the poles, often with other chromosomes lagging in intermediate positions.An approach of chromosomes to the poles may be caused by two different mechanisms in mitoses of this kind and only in a few cases is the information sufficient to show that active centromere movements occur during these anaphases.In many aspects of their behaviour on the spindle, single chromatids are similar to ordinary univalents of the first meiotic division. For this reason the movement mechanics of the chromosomes of the first meiotic division is briefly reviewed.The interpretation is expressed that the structure of the centromere region of a single chromatid shows some similarity to that of a univalent of the first meiotic division and that this may be the reason for their similar behaviour. The chromatid centromere would have a structural multiplicity with respect to its kinetic elements, corresponding to its subdivision in half-chromatids and also to the presence of two or three consecutive chromomeres in its longitudinal direction. As these kinetic elements are arranged close to one another on one side of the narrow cylinder of the centromere constriction, it is difficult for them to orient, towards both poles simultaneously. A single chromatid having a centromere of this kind will show orientation instability and change its orientation between the two unipolar orientations and various more or less bipolar orientations. The movements following these different orientations would cause the scattering of these single chromatids over the spindle. The orientation of ordinary mitotic metaphase chromosomes, consisting of two such chromatids, could often be the consequence of a process of co-orientation similar to that in meiotic bivalents.The anaphase movement of undivided chromosomes, which by active centromere movements are shifted in the polar directions without a separation of daughter components, is discussed with reference to a similar behaviour observed by Dietz in multivalents in Ostracods. These multivalents are stabilized in the equator during metaphase, in spite of the fact that they have two or three centromeres directed towards one pole and a single one towards the other. During anaphase their chromosomes do not separate but the whole configurations are shifted towards that pole towards which the majority of the centromeres are directed (this is followed by another type of movement which does not concern us in this connection). Undivided chromosomes that are oriented with more of their kinetic material towards one of the poles and less towards the other should by the same mechanisms as moved the multivalents be shifted in the equatorial direction during metaphase and in the polar direction during anaphase. The mechanism of these events is obscure. A change in the interpretation given by Dietz is suggested.This paper is dedicated to Professor Franz Schrader on the occasion of his seventieth birthday.