Chromosomal analysis of couples with repeated spontaneous abortions in northeastern iran.

BACKGROUND: Cytogenetic study of reproductive wastage is an important aspect in determining the genetic background of early embryogenesis. Approximately 15 to 20% of all pregnancies in humans are terminated as recurrent spontaneous abortions (RSAs). The aim of this study was to detect chromosome abnormalities in couples with RSAs and to compare our results with those reported previously. MATERIALS AND METHODS: In this retrospective study, the pattern of chromosomal aberrations was evaluated during a six-year period from 2005 to 2011. The population under study was 728 couples who attended genetic counseling services for their RSAs at Pardis Clinical and Genetics Laboratory, Mashhad, Iran. RESULTS: In this study, about 11.7% of couples were carriers of chromosomal aberrations. The majority of abnormalities were found in couples with history of abortion, without stillbirth or livebirth. Balanced reciprocal translocations, Robertsonian translocations, inversions and sex chromosome aneuploidy were seen in these cases. Balanced reciprocal translocations were the most frequent chromosomal anomalies (62.7%) detected in current study. CONCLUSION: These findings suggest that chromosomal abnormalities can be one of the important causes of RSAs. In addition, cytogenetic study of families who experienced RSAs may prevent unnecessary treatment if RSA are caused by chromosomal abnormalities. The results of cytogenetic studies of RSA cases will provide a standard protocol for the genetic counselors in order to follow up and to help these families.

Pattern of chromosomal aberrations in patients from north East iran.

OBJECTIVE: Chromosomal aberrations are common causes of multiple anomaly syndromes. Recurrent chromosomal aberrations have been identified by conventional cytogenetic methods used widely as one of the most important clinical diagnostic techniques. MATERIALS AND METHODS: In this retrospective study, the incidences of chromosomal aberrations were evaluated in a six year period from 2005 to 2011 in Pardis Clinical and Genetics Laboratory on patients referred to from Mashhad and other cities in Khorasan province. Karyotyping was performed on 3728 patients suspected of having chromosomal abnormalities. RESULTS: The frequencies of the different types of chromosomal abnormalities were determined, and the relative frequencies were calculated in each group. Among these patients, 83.3% had normal karyotypes with no aberrations. The overall incidences of chromosomal abnormalities were 16.7% including sex and autosomal chromosomal anomalies. Of those, 75.1 % showed autosomal chromosomal aberrations. Down syndrome (DS) was the most prevalent autosomal aberration in the patients (77.1%). Pericentric inversion of chromosome 9 was seen in 5% of patients. This inversion was prevalent in patients with recurrent spontaneous abortion (RSA). Sex chromosomal aberrations were observed in 24.9% of abnormal patients of which 61% had Turner's syndrome and 33.5% had Klinefelter's syndrome. CONCLUSION: According to the current study, the pattern of chromosomal aberrations in North East of Iran demonstrates the importance of cytogenetic evaluation in patients who show clinical abnormalities. These findings provide a reason for preparing a local cytogenetic data bank to enhance genetic counseling of families who require this service.

Two novel mutations in CYP11B1 and modeling the consequent alterations of the translated protein in classic congenital adrenal hyperplasia patients.

Mutations in the 11ß-hydroxylase (CYP11B1) gene are the second leading cause of congenital adrenal hyperplasia (CAH), an autosomal recessive disorder characterized by adrenal insufficiency, virilization of female external genitalia, and hypertension with or without hypokalemic alkalosis. Molecular analysis of CYP11B1 gene in CAH patients with 11ß-hydroxylase deficiency was performed in this study. Cycle sequencing of 9 exons in CYP11B1 was performed in 5 unrelated families with 11ß-hydroxylase deficient children. Three-dimensional models for the normal and mutant proteins and their affinity to their known substrates were examined. Analysis of the CYP11B1 gene revealed two novel mutations, a small insertion in exon 7 (InsAG393) and a small deletion in exon 2 (DelG766), and three previously known missense mutations (T318M, Q356X, and R427H). According to docking results, the affinity of the protein to its substrates is highly reduced by these novel mutations. DelG766 has more negative impact on the protein in comparison to InsAG393. The novel mutations, InsAG393 and DelG766, change the folding of the protein and disrupt the enzyme's active site as it was measured in the protein modeling and substrate binding analysis. Molecular modeling and sequence conservation were predictive of clinical severity of the disease and correlated with the clinical diagnosis of the patients.

Gene dosage analysis of proximal spinal muscular atrophy carriers using real-time PCR.

BACKGROUND: Autosomal recessive spinal muscular atrophy is a disease resulting from homozygous absence of SMN1 gene in approximately 94% of SMA patients. To identify patients who retained a single SMN1 copy, SMN1 dosage analysis was performed by quantitative Real-time PCR using SYBR green dye. SMN1 dosage analysis results were utilized to identify carriers before offering prenatal diagnosis. METHOD: Carrier testing was performed for 150 individuals. Copy number of the SMN1 gene was determined by the comparative threshold cycle (Ct) method and human serum albumin gene was used as a reference. RESULT: Analysis of 150 DNA samples with quantitative PCR determined the number of SMN1 gene copies. Of these, 50 (33.33%) cases had one SMN1 gene copy, 87 (58%) had two copies and 13 (8.66%) did not have any copies of SMN1. The homozygous SMN1 deletion ratio was 0.00 and deletion of one copy of SMN1 gene ratio ranged from 0.3 to 0.58. CONCLUSION: This report demonstrates modification of risk estimation for the diagnosis and detection of SMA carriers by accurate determination of SMN1 copy number. SMN1 copy number analysis is an important parameter for identification of couples at risk of having children affected with SMA. It also reduces unwarranted prenatal diagnosis for SMA. Furthermore, the dosage analysis might be useful for the counseling of clinically suspected SMA patients with negative diagnostic SMA tests.