Mahmut Balkan

Truncating mutations in TAF4B and ZMYND15 causing recessive azoospermia

Background Azoospermia is the absence of a measurable level of spermatozoa in the semen. It affects approximately 1% of all men, and the genetic basis of the majority of idiopathic cases is unknown. We investigated two unrelated consanguineous families with idiopathic azoospermia. In family 1, there were three azoospermic brothers and one oligozoospermic brother; and in family 2, there were three azoospermic brothers. Testis biopsy in the brothers in family 2 had led to the diagnosis of maturation arrest in the spermatid stage. Methods Candidate disease loci were found via linkage mapping using data from single nucleotide polymorphism genome scans. Exome sequencing was applied to find the variants at the loci. Results We identified two candidate loci in each family and homozygous truncating mutations p.R611X in TAF4B in family 1 and p.K507Sfs*3 in ZMYND15 in family 2. We did not detect any mutations in these genes in a cohort of 45 azoospermic and 15 oligozoospermic men. Expression studies for ZMYND15 showed that the highest expression was in the testis. Conclusions Both genes are known to have roles in spermatogenesis in mice but neither has been studied in humans. To our knowledge, they are the first genes identified for recessive idiopathic spermatogenic failure in men. Assuming that recessive genes for isolated azoospermia are as numerous in men as in mice, each gene is possibly responsible for only a small fraction of all cases.

CYTOGENETIC ANALYSIS OF 4216 PATIENTS REFERRED FOR SUSPECTED CHROMOSOMAL ABNORMALITIES IN SOUTHEAST TURKEY

We reviewed cytogenetic studies performed on 4216 patients who were referred to the Cytogenetics Unit at Dicle University Hospital, Diyarbair, Southeast Turkey, between 2000 and 2009. The cases were grouped according to the reason of referral for cytogenetic analysis. The frequencies of the different types of numerical and structural abnormalities were determined, and the relative frequency of cases with abnormal karyotypes was calculated in each group. The most common reason for requesting cytogenetic testing was referral for Down syndrome and for repeated abortions. The highest frequencies of abnormal karyotypes were found among cases that were referred due to suspicion of Down syndrome (84.8%). Among the chromosomal abnormalities, sexual chromosomal abnormalities were found in 239 cases (17.6%), and Klinefelter syndrome was the most frequent sex chromosomal abnormality. Autosomal abnormalities were found in 1119 cases (82.4%), and Down syndrome was the most frequent autosomal chromosomal abnormality. In conclusion, the high rate of chromosomal abnormalities (32.2%) found in this population demonstrates the importance of cytogenetic evaluation in patients who show clinical abnormalities. This is the first report on cytogenetic testing in the southeast region of Turkey. This type of study provides a basis for determining the risks of recurrence and for deciding on clinical treatment and genetic counseling.

FSHR Single Nucleotide Polymorphism Frequencies in Proven Fathers and Infertile Men in Southeast Turkey

The influence of FSH receptor (FSHR) variants on male infertility is not completely understood. The present investigation is the first screening study for SNP at nucleotide position −29 in the core promoter region and codon 680 in exon 10 of the FSHR and the effect of the serum levels of FSH on male infertility in Southeast Turkey. The SNPs in codon 680 and at position −29 of the FSHR gene were analyzed by PCR-RFLP technique in 240 men with proven fathers, and 270 infertile men (150 nonobstructive azoospermic and 120 severe oligozoospermic). The separate analysis for SNP at nucleotide position −29 did not show any difference in genotypic frequencies and serum FSH levels. The genotype distribution of SNP at position 680 was different but does not influence serum FSH levels. Together the two SNPs form four discrete haplotypes (A-Thr-Asn, G-Thr-Asn, A-Ala-Ser, and G-Ala-Ser) occurring in 10 combinations. A statistically significant difference in the allelic distribution of G-Asn/G-Ser and G-Ser/G-Ser genotype between proven fathers and infertile men but there were not any statistically significant difference in the overall frequency of the four FSHR haplotypes. We conclude that the FSHR haplotype does not associate with different serum FSH levels but it is differently distributed in proven fathers and infertile men.

Parental Decisions Regarding a Prenatally Detected Fetal Chromosomal Abnormality and the Impact of Genetic Counseling: An Analysis of 38 Cases with Aneuploidy in Southeast Turkey

This study investigated parental decision-making to terminate or continue a pregnancy after prenatal diagnosis of a chromosomal abnormality among a sample of patients in Southeast Turkey. Between 2004 and 2007, 1068 amniocentesis tests were performed in the Medical Biology and Genetic Department Laboratory at Dicle University. Aneuploidy was found in 38 cases (3.56%). Genetic counseling was provided for the couples that received abnormal results, and they were later interviewed and asked if they had continued or interrupted the pregnancy after the diagnosis. When confronted with autosomal aneuploidy in which a severe prognosis was expected, 85% of cases decided to terminate the pregnancy. When confronted with sex chromosome aneuploidy with a low risk of an abnormal clinical phenotype 60% of cases decided to continue the pregnancy. Among the diagnoses with aneuploidy, pregnancy was continued in 21.1% of cases due to religious beliefs regardless of whether there was a low or severe risk of an abnormal clinical phenotype. These findings indicate that both severity of abnormality and religiosity play an important role in genetic counseling patients’ decision-making processes and outcomes in Turkey. In addition, the findings suggest the need for legislation that reduces the differences in approaches between the physicians and institutions regarding parental decision-making to terminate or continue a pregnancy in our country.

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.

A small supernumerary marker chromosome, derived from chromosome 22, possibly associated with repeated spontaneous abortions.

We report a phenotypically normal couple with repeated spontaneous abortions and without other clinical features. Clinical, hematological, biochemical, and endocrinological aspects of the couple did not reveal any abnormalities. The karyotype of the wife was normal (46,XX), while the husband was found to have an abnormal karyotype, 47,XY,+der(22)mat. The marker chromosome was familial and non-satellite. Although the potential risk of small supernumerary marker chromosomes for spontaneous abortions cannot be defined precisely, marker chromosomes, together with methods used for ascertainment, are also factors to be considered when investigating infertility consequences. Furthermore, identification of the origin of a marker chromosome may provide additional information for patient karyotype-phenotype correlations. Further studies, such as molecular analyses to identify the breakpoint, are necessary for investigating phenotype-genotype correlations and assessment of genetic risks for small secondary chromosomes. The cause of repeated spontaneous abortions in this couple might be the presence of this marker chromosome in the husband. Consequently, we recommended genetic counseling before further pregnancies.

Tetrasomy 18p in a male dysmorphic child in southeast Turkey

Small supernumerary chromosomes (sSMC) of an unknown origin are commonly referred to as ‘marker chromosomes’ or ‘ESACs’ (extra structurally abnormal chromosomes) (Blennow et al. 1993; Pietrzak et al. 2007). They are found in an about 0.043% of the human population and have been estimated to result in an abnormal phenotype approximately 30% of sSMC carriers (Pietrzak et al. 2007). Isochromosomes are supernumerary marker chromosomes, that are made up of two copies of the same arm of a chromosome, so that they form a mirror image of each other, resulting in a tetrasomy of the arm involved (Boyle et al. 2001; Ramegowda et al. 2006). Prevalence of various kinds of isochromosomes range from 0.14 to 0.72 per 1000 live births (Boyle et al. 2001; Ramegowda et al. 2006). The presence of a supernumerary isochromosome 18p results in tetrasomy of 18p (Boyle et al. 2001; Bakshi et al. 2006; Ramegowda et al. 2006). Tetrasomy of 18p is found one in every 140,000 live births, affecting males and females equally (Ramegowda et al. 2006). The tetrasomy 18p syndrome most often expresses itself with moderate to severe mental impairment, very delayed speech, poor or nonexistent ability to self feed, much delayed ability to walk, microcephaly, a long, asymmetric face, low set or malformed ears, a small pinched nose, short palpebral fissures, a small jaw, and congenital heart diseases, etc. (Callen et al. 1990; Boyle et al. 2001; Bakshi et al. 2006; Ramegowda et al. 2006). The characterization of marker chromosomes by conventional cytogenetic methods can be difficult, and these methods allow only the first step of diagnosis of isochromosomes, whereas fluorescence in situ hybridization (FISH) is the most common, rapid and reliable technique used to delineate isochromosomes (Gocke et al. 1986; Callen et al. 1990; Ramegowda et al. 2006; Pietrzak et al. 2007).

Possible Association of FAS and FASLG Polymorphisms with the Risk of Idiopathic Azoospermia in Southeast Turkey

To investigate the association of the genetic variants of FAS/FASLG cell death pathway genes in male infertility, we genotyped the FAS -670A/G, -1377G/A, and FASLG -124A/G single-nucleotide polymorphisms (SNPs) by real-time polymerase chain reaction in 108 infertile men with idiopathic azoospermia and in 125 proven fertile controls. The distribution of genotypes and alleles for SNPs at FAS -1377G/A and FASLG -124A/G loci were determined not to be statistically different between the case and control groups. However, the genotype frequencies of SNPs, FAS -670AA and FAS -670AG, were found to be significantly different between the case and control groups. Whereas the FAS -670AA genotype might be regarded as a higher predisposition for idiopathic azoospermia, FAS -670AG could be interpreted to mean that this genotype provides protection against idiopathic azoospermia. The study of combined genotype and haplotype frequencies has found statistically significant differences between case and control subjects for some combinations. The AA-GG binary genotype for the FAS670 and FAS1377 loci couple, in particular, may have a high degree of predisposition to idiopathic azoospermia. Our results suggest that FAS -670A/G SNP may be a genetic predisposing factor of idiopathic azoospermia among southeastern Anatolian men. Larger studies are needed to verify these findings. Furthermore, our data indicated a possible linkage between the FAS and FASLG genes and idiopathic azoospermia.

Cytogenetic and clinical studies of a male infant with disorder of sexual development: case report

OBJECTIVE To report a translocation between chromosomes 3 and 4: 46,XY,t(3;4)(p25;q31.3) in a male infant with a disorder of sexual development. DESIGN Case report. SETTING University hospital. PATIENT(S) A 1-year-old infant who presented with abnormal location of the urethral meatus. INTERVENTION(S) Cytogenetic analysis, fluorescence in situ hybridization (FISH), and serum concentrations measurement (using peripheral blood), and clinical examination. MAIN OUTCOME MEASURE(S) Karyotype and clinical findings. RESULT(S) On clinical examination, bilateral testicular volume and phallus were determined to be undersized. Serum concentrations of T and DHEAS were low. G-banding of his chromosomes showed that the patient had a balanced translocation involving chromosomes 3 and 4: 46,XY,t(3;4)(p25;q31.3). This karyotype finding was confirmed by FISH. The FISH analysis revealed the presence of sex-determining region (SRY). The proband inherited this translocation from his father. His sister had the same translocation. However, the father and sister of the proband were clinically normal. CONCLUSION(S) The presence of this chromosomal anomaly and hypospadias was unique to our patient compared with others with the 46,XY,t(3;4) translocation. Although no such association has been reported to date, we think that the severe hypospadias in our case might be associated with this translocation.

Patau Sendromlu Bir Prenatal Tani Olgu Sunumu

The aim of this study was to determine the effect of carbamazepine onserum lipid levels in epileptic patients who were on long-termcarbamazepine monotherapy. The study group were comprised of 30epileptic patients (10 female, 20 male) who have been on carbamazepinemonotherapy for at least one year whereas control group consisted of 30 ageand sex matched healthy controls. Serum cholesterol (total cholesterol,HDL cholesterol, LDL cholesterol) and triglyceride levels were measuredand LDL/HDL ratio was calculated in all subjects. Serum HDL cholesteroland triglyceride levels of study group were significantly higher than controlgroup whereas serum LDL cholesterol levels and LDL/HDL ratios of studygroup were lower than control group. Mean total cholesterol level of studygroup was lower than control group, however the difference did not reachstatistical significance level. Because of its effect on cholesterol levels, longterm carbamazepine could possibly have a positive influence in decreasingthe risk of developing aterosclerosis and coronary heart disease. Long termprospective follow-up studies would be helpful to us in enlightening this issuedefinitely.