Venkata Padmalatha

Mutational screening of the coding region of growth differentiation factor 9 gene in Indian women with ovarian failure

Objective:To establish the risk associated with mutations in the coding region of GDF9 gene in Indian women with ovarian failure. Design:This case-control study was designed for mutational analysis of the GDF9 coding region in a cohort of women with premature ovarian failure (n = 127), primary amenorrhea (n = 58), and secondary amenorrhea (n = 10) compared with controls (n = 220). Results:This case-control study revealed eight mutations in the GDF9 gene, including five novel mutations: c.1-8C>T, c.199A>C (p.Lys67Glu), c. 205C>T, c.646G>A (p.Val216Mat), and c.1353C>T, and three documented mutations: c.398-39C>G, c.447C>T, and c.546G>A. Missense mutation c.199A>C was present in 4 of 127 premature ovarian failure (POF) cases and 1 of 10 secondary amenorrhea cases. The c.646G>A mutation was present in two POF cases. Both missense mutations were absent in controls. Genotype distribution of c.447C>T was significantly different in POF cases than controls (χ2 = 5.93, P = 0.05). We chose two frequent single-nucleotide polymorphisms (c.398-39C>G, c.447C>T) for haplotyping and found that the C-T haplotype was significantly higher in patients (P = 0.03), whereas the C-C haplotype was representative of the control group. Conclusions:We report two rare missense mutations, c.199A>C and c.646G>A, which are associated with ovarian failure. The presence of the c.447>T mutation might indicate a higher risk for POF. Haplotype C-T was significantly associated with ovarian failure, whereas the C-C haplotype was representative of the control group.

Genes governing premature ovarian failure

Premature ovarian failure (POF) is unexplained amenorrhoea (>6 months), increased FSH (>20 IU/l) and LH occurring before 40 years. Several genes are reported as having significance in POF, including genes governing regulation of the hypothalamic-pituitary-ovarian axis, but their role in ovarian physiology is not known. Deletions or translocations in Xq arm have been found to be associated with POF, assuming presence of ovarian-related genes but ovary-related function of these genes is unclear. Several researchers have suggested specific loci on Xq critical region, POF1 and POF2 and genes DIA, FMR1 and FMR2. The understanding of ovarian physiology, its regulation and genes involved is important to explain the causes of POF. Some genes coordinate development of germ cell to primordial stage, e.g. GDF9, BMP15 and NGF, while others regulate development of further stages, such as FSH and LH. Mutation in these genes may lead to female infertility and are likely to be candidate genes for POF. Recently, association between blepharophimosis-ptosis-epicanthus inversus syndrome type 1 and POF has emerged as a possibility. Galactosaemia is also shown to be important in POF due to toxic effects of accumulated galactose or downstream products. Thus, understanding the role of several genes can be used for the appropriate genetic diagnosis, research and in the clinical practice of POF.

Association Between Novel HLA-G Genotypes and Risk of Recurrent Miscarriages: A Case-Control Study in a South Indian Population:

HLA-G is a nonclassical histocompatibility complex member associated with fetal tolerance of the mother observed during pregnancy. Despite its being a less polymorphic gene, a number of studies have evaluated the role of HLA-G gene polymorphisms on the risk of pregnancy-related complications. A 14-bp deletion polymorphism in exon 8 (3′UTR) was known to influence the levels of soluble HLA-G, differential splicing of the transcript, and also the induction of interleukin-10 secretion. The present study is aimed at evaluating the variations in exon 2 and exon 8 of the HLA-G gene for the risk of recurrent miscarriages in South Indian women. A total of 169 cases and 92 controls are included in the study. Six novel polymorphisms were identified, 2 of which are in intron 2 near the exon-intron junction and 4 of which are present downstream to the 14-bp deletion in 3′UTR. The exon 2 and intron polymorphisms failed to show any association. The T1570C and C1594A polymorphisms showed a significant association (P = .002 and .021) with the risk of miscarriage after categorization based on the 14-bp deletion. Linkage disequilibrium analysis showed that the T allele of T1570C is in linkage disequilibrium with the 14-bp deletion in cases but not in controls. In silico RNA folding studies indicate that the T allele forms a more stable secondary structure than the C allele, giving rise to a more stable transcript.The authors demonstrate a significant relation between the two 3′UTR polymorphisms and recurrent miscarriages.

Germline study of AR gene of Indian women with ovarian failure

Objective. Present study was designed for carrying out the mutational analysis of the entire Androgen receptor (AR) gene including two microsatellite (CAG)n, (GGN)n, promoter region in cases of premature ovarian failure (POF) and primary amenorrhea (PA). Design. Previous reports of AR knockout mice model showed POF phenotype, this draws an attention on the role of AR gene in the aetiology of POF for the case–control association studies in POF samples (n = 133), PA samples (n = 63) and control samples (n = 200). Results. We identified six mutations including four novel mutations, i.e. c.636G > A, c.1885 + 9C > A, c.1948A > G, c.1972C > A, and two previously reported mutations, i.e. c.639G > A, c.2319−78T > G. Repeat length variation was noted in the two microsatellite regions CAG and GGN, located in the coding region of exon 1 at the N-terminal region of the AR gene. The CAG repeat length was homogenously distributed with the same frequency and no association among all cases and controls. The GGN repeat showed a significant association among the SS and SL allele with p = 0.0231 and p = 0.0476, respectively, among the POF/control samples. Conclusions. Thus, AR gene mutations may play a role in the genetic cause of POF. Identification of the underlying genetic alteration of the AR gene is important for a proper diagnosis of POF subjects.

Novel X‐chromosomal defect associated with abnormal ovarian function

Premature ovarian failure (POF) may be idiopathic or may be associated with genetic or autoimmune disorders. It is well known that chromosomal defects can impair ovarian development and its function. It is estimated that X‐chromosome abnormalities occur in 10–25% of women with abnormal ovarian function. Of these, the common chromosome defects reported are either true Turners karyotype or its variants. We describe a novel X‐chromosome aberration in a woman with primary amenorrhea. Cytogenetic and florescence in situ hybridization analysis revealed a short‐arm deletion of X‐chromosome as a Turners variant [mos,45,XO/46,Xdel(X)(p11.1–p22.3)]. This interesting and rare case with unique X‐chromosome defect reveals an additional mechanism for the cause of POF.

Unique case reports associated with ovarian failure: necessity of two intact x chromosomes.

Premature ovarian failure is defined as the loss of functional follicles below the age of 40 years and the incidence of this abnormality is 0.1% among the 30–40 years age group. Unexplained POF is clinically recognized as amenorrhoea (>6 months) with low level of oestrogen and raised level of Luteinizing Hormone (LH) and Follicle Stimulating Hormone (FSH > 20 IU/l) occurring before the age of 40. It has been studied earlier that chromosomal defects can impair ovarian development and its function. Since there is paucity of data on chromosomal defects in Indian women, an attempt is made to carry out cytogenetic evaluation in patients with ovarian failure. Cytogenetic analysis of women with ovarian defects revealed the chromosome abnormalities to be associated with 14% of the cases analyzed. Interestingly, majority of the abnormalities involved the X-chromosome and we report two unique abnormalities, (46,XXdel(Xq21-22) and q28) and (mos,45XO/46,X+ringX) involving X chromosome in association with ovarian failure. This study revealed novel X chromosome abnormalities associated with ovarian defects and these observations would be helpful in genetic counseling and apart from, infertility clinics using the information to decide suitable strategies to help such patients.

De novo 7p partial trisomy characterized by subtelomeric FISH and whole-genome array in a girl with mental retardation

Chromosome rearrangements involving telomeres have been established as one of the major causes of idiopathic mental retardation/developmental delay. This case of 7p partial trisomy syndrome in a 3-year-old female child presenting with developmental delay emphasizes the clinical relevance of cytogenetic diagnosis in the better management of genetic disorders. Application of subtelomeric FISH technique revealed the presence of interstitial telomeres and led to the ascertainment of partial trisomy for the distal 7p segment localized on the telomeric end of the short arm of chromosome 19. Whole-genome cytogenetic microarray-based analysis showed a mosaic 3.5 Mb gain at Xq21.1 besides the approximately 24.5 Mb gain corresponding to 7p15.3- > pter. The possible mechanisms of origin of the chromosomal rearrangement and the clinical relevance of trisomy for the genes lying in the critical regions are discussed.

Paternally derived translocation t(8;18)(q22.1;q22)pat associated in a patient with developmental delay: Case report and review

The common cause of mental impairment and the wide range of physical abnormalities is balanced chromosome rearrangement. As such, it is difficult to interpret, posing as a diagnostic challenge in human development. We present a unique familial case report with the paternally inherited autosomal-balanced reciprocal translocation involving chromosomal regions 8q and 18q. The etiology of the translocation, i.e. 46,XX,t(8;18)(q22.1;q22) was detected by conventional high-resolution Giemsa–Trypsin–Giemsa-banding and fluorescence in situ hybridization techniques. The father was found to be the carrier of the chromosome defect and also the same was observed in the first female child referred with a history of delayed milestone development. However, the second female child showed normal 46, XX karyotype. This is the first report of reciprocal translocation involving 8q and 18q associated with the delayed milestone development. The reason likely may be due to the rearrangement of genetic material at these breakpoints having a crucial relationship and thus manifesting developmental delay in the progeny. Accordingly, this paper also shows genetic counseling discussion for the cause.

Y chromosome microchimerism in female peripheral blood

Male DNA of recognized fetal origin can be detected in the maternal circulation many years after delivery. It is referred to as fetal microchimerism, and is thus a possible explanation for the existence of low-level Y chromosome mosaicisms. Employing the nested polymerase chain reaction (PCR) technique, Y-specific markers were investigated in 13 cases with abnormal sex chromosome and 31 normal women. Sex-determining region Y (SRY) sequences were detected in normal women with a male child, which reflects the existence of fetal progenitor cells in the maternal circulation. This was completely absent in normal women with a female child. Individuals with the Y chromosome showed amplification for Y-specific markers. Microchimerism of Y was noted in Turner phenotype cytogenetically investigated with marker chromosome, and in an individual with XX karyotype. False positive amplifications are possible in nested PCR reactions, but the same could also be true for routine PCR. However, in the absence of any identifiable factor that could contribute to the recurrence of spurious PCR amplifications, cases of therapeutic importance must be tested at least five times. In such situations, DNA from an additional tissue should also be used for nested PCR.