The Types and Frequencies of X Chromosome Abnormalities in Women with Reproductive Problems

INTRODUCTION

X chromosome architecture and integrity are essential for normal ovarian function. Both numerical and structural X chromosome abnormalities play an important role in female infertility. This study aimed to determine the types and frequency of X chromosome aberrations detected in women referred for cytogenetic investigation due to reproductive problems.

METHODS

2,936 women (average age: 37.5 years) were enrolled in the present study. Peripheral blood karyotyping was performed by conventional cytogenetic techniques. For each woman, 20 G-banded metaphases were studied and in case of suspected mosaicism, analysis was extended to 100 metaphases.

RESULTS

2,588/2,936 (88.15%) of women had a normal karyotype (46,XX), while 348/2,936 (11.85%) had an abnormal one. Thirty-two women (1.09%) carried autosomal chromosome abnormalities and 316 (10.76%) had X chromosome rearrangements. In 311/2,936 women (10.59%), X chromosome numerical aberrations were detected (low-level mosaicism), and in 5/2,936 cases (0.17%), X structural abnormalities (two with pericentric inversion, one with Xq deletion and two 45,X mosaics, one with an Xp deletion cell line and the other with isochromosome Xq cell line). Low-level X mosaicism was a common finding in women >35 years as compared to younger ones (92.93% vs. 7.07%), a finding consistent with loss of chromosome X with aging. Other X chromosome abnormalities were detected in younger women (32.3 ± 4.13 vs. 41.04 ± 4.5 years). The mean age of women with Turner-like phenotype was 28.75 ± 6.6 years.

CONCLUSION

The study confirms that the incidence of X chromosome abnormalities is increased in women with fertility problems and that karyotype is the gold standard for their identification. Genetic counseling is recommended in these cases to provide information concerning available treatment and fertility options.

Female Reproductive Ageing and Chromosomal Abnormalities in a Large Series of Women Undergoing IVF

Chromosomal abnormalities are often detected in women with reproductive problems. This study aimed to investigate the presence and type of chromosomal aberrations in peripheral blood of women undergoing in vitro fertilization (IVF) and their possible association with advanced maternal age (AMA). A total of 1,837 women undergoing IVF between 2016 and 2019 were enrolled in the study. Women were further divided in AMA (≥35 years) and younger women (<35 years). Chromosomal abnormalities were detected by peripheral blood karyotyping using standard cytogenetic techniques. Chromosomal abnormalities were detected in 13.5% of the enrolled women; 1.1% had autosomal abnormalities including reciprocal translocations, inversions, Robertsonian translocations, and a supernumerary marker chromosome, while 12.4% had X chromosome abnormalities. The frequency of chromosomal abnormalities was significantly higher in AMA women than in younger ones (17.4% vs. 3.9%, p < 0.05). Women of AMA exhibited X chromosome mosaicism with a frequency of 16.1%, and mosaic karyotypes with 2 and 3 aneuploid cell lines were more frequently detected. X chromosome mosaicism is the most common karyotypic aberration in women undergoing IVF and has 6-fold increased incidence in AMA women compared to younger ones. The present study verifies previous observations that low-level peripheral blood X chromosome mosaicism and the number of aneuploid cell lines observed in women of AMA could be an indication of aneuploidy and poor quality of oocytes contributing to infertility.

Cytogenetic findings of ectopic endometriotic tissue in women with endometriosis and review of the literature

OBJECTIVE

To determine chromosome and gene alterations in ectopic endometrial (EM) tissue which may be implicated in the clinical course or the progression of endometriosis and to review the literature concerning the cytogenetic findings of women with endometriosis.

STUDY DESIGN

15 women who underwent laparoscopic endometriosis surgery at the Athens Genesis Clinic were enrolled in the study. Ectopic endometrial tissue was surgically removed and further analyzed by conventional and molecular cytogenetic techniques. Fluoresent in situ hibridization (FISH) with probes for p53, ATM, MYC, MLL1 and IGH genes, the centromeres of chromosomes 7 and 8 and 7q22/7q31 chromosomal regions was carried out.

RESULTS

Karyotypic analysis revealed no clonal chromosomal abnormalities. However, an increased frequency of polyploidy (55.6%) and sporadic chromosomal abnormalities (40.0%) concerning chromosomes 9, 11, 17 and X were noticed involving mainly deletions, trisomies or monosomies. FISH analysis showed IGH gene rearrangements in 54% of the EM cases and MLL gene rearrangements in 73% of the examined samples. Normal hybridization patterns were observed for p53, ATM and MYC. The increased frequency of polyploidy shown by conventional karyotyping was also confirmed by FISH.

CONCLUSION

Polyploidy, sporadic chromosomal abnormalities, as well as IGH and MLL gene rearrangements, may provoke genetic instability and play a potential role in the development of endometriosis. IGH and MLL gene rearrangements indicate a genetic relation between endometriosis and carcinogenesis. Confirmation of the above gene rearrangements in a large series of women may allow the determination of their possible involvement in the pathogenesis of this complex disease and their possible contribution in the early identification of women in danger for malignant transformation.

Detection of a novel unbalanced X;21 translocation in a girl with Turner syndrome phenotype

OBJECTIVE

To describe a novel unbalanced X;21 translocation resulting in a derivative pseudodicentric chromosome X;21 lacking the critical region for ovarian development and function, in a 16-year-old girl referred for cytogenetic analysis due to primary amenorrhea and Turner-like features.

METHODS

Cytogenetic analysis of the proband and her parents was performed on peripheral blood lymphocytes by GTG banding. Molecular cytogenetic FISH analysis was performed on metaphase preparations, using X chromosome centromeric probe and telomeric and pancentromeric peptide nucleic acid (PNA) analog probes. The HUMARA assay as well as methylation studies for PCSK1N and FMR-1 loci were performed.

RESULTS

Cytogenetic analysis revealed a de novo unbalanced X;21 translocation, described as 45,X,der(X)t(X;21)(q22.2;p11.2),-21. FISH analysis showed that the derivative X chromosome carried both the X and 21 centromeres, as well as, the Xp and 21q telomeres. The karyotype was thus reevaluated as 45,X,psu dic(21;X)(21qter→21p13::Xq22.2→Xpter),-21. X inactivation studies revealed that the derivative chromosome was of paternal origin and confirmed the selective inactivation of the derivative X segment of the pseudodicentric chromosome.

CONCLUSIONS

Primary amenorrhea and other Turner-like characteristics of the proband are apparently due to the loss of the Xq22.2→Xqter critical region which contains critical genes for the ovarian development and function. The chromosome X segment of the derivative pseudodicentric chromosome is selectively inactivated, but inactivation does not seem to spread onto the translocated chromosome 21, accounting probably for the lack of severe clinical consequences which would result from monosomy 21.

Low-level X Chromosome Mosaicism: A Common Finding in Women Undergoing IVF

BACKGROUND/AIM

To determine the incidence of X chromosome mosaicism in women undergoing in vitro fertilization (IVF) treatment and present preimplantation genetic testing for aneuploidy (PGT-A) outcome of this group.

PATIENTS AND METHODS

A total of 1,058 women undergoing IVF and 154 women with no fertility problems were enrolled in the study. Karyotyping from peripheral blood lymphocytes was performed by conventional cytogenetics. Twenty-nine women with X mosaicism underwent PGT-A by array-comparative genomic hybridization from embryos at the blastocyst stage.

RESULTS AND CONCLUSION

Out of 1,058 women undergoing IVF, 166 (15.7%) had an abnormal karyotype. The most common finding (14.6%) was X chromosome mosaicism. Its frequency was higher in women >35 years old and reached 46.1% in those >45 years of age. PGT-A results of 130 blastocysts tested showed that 29/117 (24.8%) were euploid; 17/29 (60%) were transferred and 10/17 (70%) were successfully implanted, indicating that PGT-A may be an option for women with low-level X chromosome mosaicism undergoing IVF in order to improve the likelihood of a successful pregnancy outcome.

Perinatal lipocalin-2 profile at the extremes of fetal growth

BACKGROUND

Lipocalin-2 (LCN-2) has been identified as an osteoblast-secreted hormone regulating immunity, inflammation and metabolic homeostasis and has emerged as a diagnostic and prognostic biomarker for acute kidney injury in neonates. We investigated the impact of fetal growth on antepartum maternal serum, cord serum and breast milk LCN-2 concentrations and the associations of the latter with perinatal parameters.

METHODS

Maternal serum, cord serum and breast milk LCN-2 concentrations were measured by ELISA in samples from 80 mothers who delivered 40 appropriate (AGA), 20 large for gestational age (LGA) and 20 intrauterine growth restricted (IUGR) neonates, classified by customized weight centiles. LCN-2 concentrations were associated with birth weight, customized centile, gender, maternal age and delivery mode.

RESULTS

Antepartum maternal serum LCN-2 concentrations were significantly higher in women delivering AGA infants compared to the other two groups. Cord blood LCN-2 concentrations were significantly higher compared to maternal ones; furthermore, they were significantly elevated in the IUGR group compared to the LGA one (p = .019). Lowest concentrations were detected in breast milk, which did not differ between the three growth groups. A negative correlation was documented between cord blood LCN-2 concentrations and customized centiles (r: -0.304, p = .007).

CONCLUSIONS

The higher cord serum LCN-2 concentrations, compared to maternal ones, may point to its fetal origin and potential role in intrauterine growth. The negative correlation of cord LCN-2 concentrations with customized centiles, possibly implies reduced nephron endowment/subclinical kidney damage in IUGR neonates. The extremely low LCN-2 breast milk concentrations could imply that the secretion of LCN-2 from maternal circulation to breast milk is not influenced by factors leading to intrauterine growth pathology.

Paraoxonase 1 (PON1) Q192R and L55M Polymorphisms as Potential Predisposition Factors for Chronic Lymphocytic Leukemia

BACKGROUND/AIM

PON1 gene has an executive role in antioxidant defense, protecting cells from genotoxic factors. Q192R and L55M PON1 polymorphisms reduce catalytic activity of the encoded protein. These polymorphisms were studied in 300 chronic lymphocytic leukemia (CLL) patients and 106 healthy donors. They were also associated with patients' cytogenetic findings, to investigate their possible implication in CLL pathogenesis.

MATERIALS AND METHODS

SNP genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. Karyotypic analysis was also performed by chromosome G-banding analysis and fluorescence in situ hybridization.

RESULTS

Genotypic and allelic distribution of Q192R polymorphism showed a statistically significant higher frequency of mutant genotypes and mutant alleles in patients compared to controls. The same observation was noted in patients with abnormal karyotypes and those carrying abn14q32 and del(6q). A statistically increased frequency for the mutant allele was also revealed in patients with del(11q). On the contrary, L55M polymorphism showed a similar distribution between patients and controls.

CONCLUSION

Q192R polymorphism plays a role in CLL predisposition and the formation of specific chromosomal aberrations.

Cohesin RAD21 Gene Promoter Methylation in Patients with Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults and is characterized by the presence of specific cytogenetic abnormalities. CLL research has been focused on epigenetic processes like gene promoter methylation of CpG islands. In the present study, the methylation status of the RAD21 gene is studied and associated with cytogenetic findings in CLL patients in order to investigate its possible implication in CLL pathogenesis and the formation of CLL chromosomal abnormalities.

GSTP1 and CYP2B6 Genetic Polymorphisms and the Risk of Bronchopulmonary Dysplasia in Preterm Neonates

Objectives Antioxidant response plays a key role in bronchopulmonary dysplasia (BPD) pathogenesis. The glutathione-S-tranferases pi 1 (GSTP1) and cytochrome P450 (CYP) detoxification enzymes protect cells from oxidative damage. The aim of the study was to investigate whether the A³¹³G GSTP1 and G⁵¹⁶T CYP2B6 inactivating polymorphisms could be associated with BPD susceptibility. Study Design To test this hypothesis, we conducted a case-control study enrolled 138 premature neonates ≤32 weeks of gestational age; of the 138, 46 developed BPD and 92 did not develop BPD. Genomic deoxyribonucleic acid was extracted from neonates' peripheral blood and was used as template for GSTP1 and CYP2B6 genotyping using the real-time polymerase chain reaction method. Results Our report provides evidence for a possible pathogenetic role of the G⁵¹⁶T CYP2B6 polymorphism in BPD susceptibility. Although no differences in the frequencies of the GSTP1 variant genotypes were noticed between premature neonates who developed BPD and neonates who did not develop BPD, a significantly higher frequency of the GSTP1 polymorphism was observed in extremely low birth weight infants. Despite the small sample size, it is very interesting the fact that all neonates ≤1,000 g carrying the homozygous mutant GSTP1 genotype developed BPD. Conclusion Our results underscore the significance of both CYP2B6 and GSTP1 polymorphisms in modulating the risk of BPD.

Possible Implication of GSTP1 and NQO1 Polymorphisms on Natalizumab Response in Multiple Sclerosis

Oxidative stress plays a pivotal role in the pathogenesis of multiple sclerosis (MS). Inactivating polymorphism of genes encoding detoxification enzymes, such as NQO1 and GSTP1 could influence susceptibility to MS. The monoclonal antibody natalizumab is an effective treatment in MS. Natalizumab's efficacy in MS patients with regard to NQO1 and GSTP1 genetic polymorphisms is investigated. 130 patients with definite MS according to the Mc Donald's criteria treated monthly with natalizumab were included in the study. MS patients were classified with regard to their clinical subtype, gender and clinical outcome after Natalizumab administration. GSTP1 and NQO1 genotyping was performed using Real-Time PCR and PCR-RFLP assays. Among our cohort of MS patients, 88.5% responded and 11.5% manifested clinical deterioration after natalizumab treatment. Statistical analysis revealed a significantly increased frequency of double NQO1 and GSTP1 mutant polymorphisms in non responders compared to the responders. Therefore, patients who carry the wild type genotype or only one polymorphism for either NQO1 or GSTP1 gene have possibly a better clinical outcome after the natalizumab therapy. Our findings indicate that antioxidant efficiency might reflect a better clinical outcome after natalizumab administration. Hence, oxidative stress reduction might be another mechanism through which natalizumab exerts its protective effect.

Association of C609T-Inborn Polymorphism of NAD(P)H: Quinone Oxidoreductase 1 with the Risk of Bronchopulmonary Dysplasia in Preterm Neonates

Objectives In bronchopulmonary dysplasia (BPD), direct exposure to oxygen therapy can damage the pulmonary epithelium via oxidative stress. The

NAD(P)H

quinone oxidoreductase 1 (NQO1) enzyme detoxifies genotoxic products of oxidative stress. The corresponding gene is subject to an inactivating single-nucleotide polymorphism (C(609)T), which reduces detoxifying ability. The aim of this study was to investigate whether the C(609)T NQO1 inborn gene polymorphism is associated with an increased risk of BPD. Study Design Peripheral blood samples from 119 premature neonates ≤ 32 weeks of gestational age (42 BPD and 77 non-BPD) were used for DNA extraction. NQO1 genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. Results A significantly higher frequency of the NQO1 polymorphism was observed in BPD neonates compared with neonates without BPD. All neonates with ≤ 1,000 g birth weight who carried the mutant allele in heterozygous or homozygous state developed BPD. None of the BPD nonaffected group neonates with ≤ 1,000 g birth weight carried the NQO1 polymorphism. Conclusion The higher incidence of NQO1 mutants among BPD neonates as well as the presence of the mutant allele in all neonates with ≤ 1,000 g who developed BPD provided the first evidence for a possible pathogenetic role of the C(609)T polymorphism in BPD susceptibility due to the reduction or loss of NQO1 enzymatic activity.

Effect of Infant Formula Containing a Low Dose of the Probiotic Bifidobacterium lactis CNCM I-3446 on Immune and Gut Functions in C-Section Delivered Babies: A Pilot Study

BACKGROUND

In the absence of breast-feeding and its immunomodulatory factors, supplementation of starter infant formula (IF) with probiotics is currently used to support immune functions and gut development.

AIM

To assess whether immune-related beneficial effects of regular dose (10⁷ CFU/g of powder) of the probiotic Bifidobacterium lactis CNCM I-3446 (hereafter named B. lactis) in starter IF supplementation can be maintained with starter IF containing a low dose (10⁴ CFU/g of powder) of B. lactis.

METHOD

This trial was designed as a pilot, prospective, double-blind, randomized, single-center clinical trial of two parallel groups (n = 77 infants/group) of C-section delivered infants receiving a starter IF containing either low dose or regular dose of the probiotic B. lactis from birth to six months of age. In addition, a reference group of infants breast-fed for a minimum of four months (n = 44 infants), also born by C-section, were included. All groups were then provided follow-up formula without B. lactis up to 12 months of age. Occurrence of diarrhea, immune and gut maturation, responses to vaccinations, and growth were assessed from birth to 12 months. The effect of low-dose B. lactis formula was compared to regular-dose B. lactis formula, considered as reference for IF with probiotics, and both were further compared to breast-feeding as a physiological reference.

RESULTS

Data showed that feeding low-dose B. lactis IF provides similar effects as feeding regular-dose B. lactis IF or breast milk. No consistent statistical differences regarding early life protection against gastrointestinal infections, immune and gut maturation, microbiota establishment, and growth were observed between randomized formula-fed groups as well as with the breast-fed reference group.

CONCLUSION

This pilot study suggests that supplementing C-section born neonates with low-dose B. lactis-containing starter formula may impact immune as well as gut maturation similarly to regular-dose B. lactis, close to the breast-feeding reference.

Comparison of Bacterial Community Composition of Primary and Persistent Endodontic Infections Using Pyrosequencing

INTRODUCTION

Elucidating the microbial ecology of endodontic infections (EIs) is a necessary step in developing effective intracanal antimicrobials. The aim of the present study was to investigate the bacterial composition of symptomatic and asymptomatic primary and persistent infections in a Greek population using high-throughput sequencing methods.

METHODS

16S amplicon pyrosequencing of 48 root canal bacterial samples was conducted, and sequencing data were analyzed using an oral microbiome-specific and a generic (Greengenes) database. Bacterial abundance and diversity were examined by EI type (primary or persistent), and statistical analysis was performed by using non-parametric and parametric tests accounting for clustered data.

RESULTS

Bacteroidetes was the most abundant phylum in both infection groups. Significant, albeit weak associations of bacterial diversity were found, as measured by UniFrac distances with infection type (analyses of similarity, R = 0.087, P = .005) and symptoms (analyses of similarity, R = 0.055, P = .047). Persistent infections were significantly enriched for Proteobacteria and Tenericutes compared with primary ones; at the genus level, significant differences were noted for 14 taxa, including increased enrichment of persistent infections for Lactobacillus, Streptococcus, and Sphingomonas. More but less abundant phyla were identified using the Greengenes database; among those, Cyanobacteria (0.018%) and Acidobacteria (0.007%) were significantly enriched among persistent infections. Persistent infections showed higher phylogenetic diversity (PD) (asymptomatic: PD = 9.2, standard error [SE] = 1.3; symptomatic: PD = 8.2, SE = 0.7) compared with primary infections (asymptomatic: PD = 5.9, SE = 0.8; symptomatic: PD = 7.4, SE = 1.0).

CONCLUSIONS

The present study revealed a high bacterial diversity of EI and suggests that persistent infections may have more diverse bacterial communities than primary infections.

The G⁵¹⁶T CYP2B6 germline polymorphism affects the risk of acute myeloid leukemia and is associated with specific chromosomal abnormalities

The etiology of acute myeloid leukemia (AML) underlies the influence of genetic variants in candidate genes. The CYP2B6 enzyme detoxifies many genotoxic xenobiotics, protecting cells from oxidative damage. The CYP2B6 gene is subjected to a single-nucleotide polymorphism (G⁵¹⁶T) with heterozygotes (GT) and homozygotes (TT) presenting decreased enzymatic activity. This case-control study aimed to investigate the association of CYP2B6 G⁵¹⁶T polymorphism with the susceptibility of AML and its cytogenetic and clinical characteristics. Genotyping was performed on 619 AML patients and 430 healthy individuals using RCR-RFLP and a novel LightSNip assay. The major finding was a statistically higher frequency of the variant genotypes (GT and TT) in patients compared to the controls (GT:38.8% vs 29.8% and TT:9.3% vs 5.3% respectively) (p<0.001). More specifically, a significantly higher frequency of GT+TT genotypes in de novo AML patients (46.6%) and an immensely high frequency of TT in secondary AML (s-AML) (20.5%) were observed. The statistical analysis showed that the variant T allele was approximately 1.5-fold and 2.4-fold higher in de novo and s-AML respectively than controls. Concerning FAB subtypes, the T allele presented an almost 2-fold increased in AML-M2. Interestingly, a higher incidence of the TT genotype was observed in patients with abnormal karyotypes. In particular, positive correlations of the mutant allele were found in patients carrying specific chromosomal aberrations [-7/del(7q), -5/del(5q), +8, +21 or t(8;21)], complex or monosomal karyotypes. Finally, a strikingly higher frequency of TT genotype was also observed in patients stratified to the poor risk group. In conclusion, our results provide evidence for the involvement of the CYP2B6 polymorphism in AML susceptibility and suggest a possible role of the CYP2B6 genetic background on the development of specific chromosomal aberrations.

High frequency of NAD(P)H:quinone oxidoreductase 1 (NQO1) C(609)T germline polymorphism in MDS/AML with trisomy 8

The NQO1 C(609)T germline polymorphism resulting in a lowering of enzyme activity may confer susceptibility to MDS. To assess this association, we performed a case-control study including 330 Greek patients with de novo MDS and 416 healthy donors, using a Real-Time PCR genotyping method. Focusing on cytogenetic aberrations most commonly found in MDS, we retrospectively genotyped 566 MDS/AML patients carrying -5/del(5q), -7/del(7q), +8, del(20q) and -Y. The case-control analysis revealed no differences in NQO1 genotype distribution. Interestingly, a 6-fold increased frequency of the homozygous variant genotype was observed among patients with isolated trisomy 8 (p<0.0001), suggesting that null NQO1 activity may influence the occurrence of +8 in MDS/AML.

Oral L-arginine supplementation and faecal calprotectin levels in very low birth weight neonates

OBJECTIVE

The objective of this study is to determine the potential effect of oral L-arginine supplementation on intestinal inflammation in very low birth weight (VLBW) neonates, as estimated by faecal calprotectin levels.

STUDY DESIGN

The study enrolled 83 VLBW neonates with birth weight ≤1500 g and gestational age ≤34 weeks. In this double-blind study, 40 neonates received daily oral L-arginine supplementation of 1.5 mmol kg(-1) per day between the 3rd and 28th day of life, and 43 neonates placebo. Stool samples were collected on days 3, 14 and 28, and calprotectin was measured by enzyme-linked immunosorbent assay.

RESULT

Calprotectin values significantly decreased over time in both groups (P=0.032). No difference in faecal calprotectin values was recorded between neonates receiving arginine supplementation and neonates receiving placebo at days 3, 14 and 28.

CONCLUSION

Faecal calprotectin values decrease with increasing postnatal age in VLBW infants, but this is not related to arginine supplementation.

Enteral L-arginine supplementation for prevention of necrotizing enterocolitis in very low birth weight neonates: a double-blind randomized pilot study of efficacy and safety

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common acquired gastrointestinal disease in premature infants and has high mortality and morbidity. Endothelial nitric oxide is an important regulator of vascular perfusion and is synthetized from the amino acid L-arginine. Hypoargininemia is frequently observed in preterm neonates and may predispose them to NEC. Our objective was to determine the effect of enteral L-arginine supplementation on the incidence and severity of NEC in very low birth weight (VLBW) neonates.

MATERIALS AND METHODS

We conducted a parallel blind randomized pilot study, comprising VLBW neonates with birth weight ≤1500 g and gestational age ≤34 weeks. VLBW neonates were randomly assigned to receive enteral L-arginine supplementation (1.5 mmol/kg/d bid) between the 3rd and 28th day of life or placebo. Diagnosis and classification of NEC were done according to modified Bell's criteria.

RESULTS

Eighty-three neonates were randomized to the arginine (n = 40) or placebo (n = 43) group. No adverse effects were observed in neonates receiving L-arginine supplementation. The incidence of NEC stage III was significantly lower in the arginine-supplemented group (2.5% vs 18.6%, P = .030).

CONCLUSIONS

Enteral L-arginine supplementation of 1.5 mmol/kg/d bid can be safely administered in VLBW neonates from the 3rd to the 28th day of life. Enteral L-arginine supplementation appears to reduce the incidence of stage III NEC in VLBW infants. Larger studies are needed to further evaluate the effect of L-arginine supplementation in preventing NEC in VLBW infants.

The C609T inborn polymorphism in NAD(P)H:quinone oxidoreductase 1 is associated with susceptibility to multiple sclerosis and affects the risk of development of the primary progressive form of the disease

Oxidative stress plays a pivotal role in the pathogenesis of multiple sclerosis (MS). Inactivating polymorphisms of genes encoding detoxification enzymes, such as NAD(P)H:quinone oxidoreductase 1 (NQO1), could influence susceptibility to MS. To test this hypothesis we performed a case-control study in which we compared the distribution of NQO1 genotypes between 231 MS patients and 380 controls, using both PCR-RFLP and real-time PCR assays. Correlations with MS clinical subtype classification and gender were also evaluated. A significantly higher frequency of the homozygous (T/T) and heterozygous (C/T) NQO1 C(609)T variant genotypes was observed among MS patients compared to controls (P=0.01), with MS patients showing a 1.5-fold increased risk of carrying at least one variant T allele (P=0.009). Interestingly, patients belonging to the primary progressive subgroup exhibited a significantly higher incidence of the heterozygous C/T variant genotype, compared to the other forms of MS (P=0.019). There was no correlation of the NQO1 polymorphism with gender. These results provide the first evidence for a pathogenetic role for the NQO1 C(609)T polymorphism in MS susceptibility and suggest a possible role for the NQO1 genetic background in the development of primary progressive MS.

Novel and known microsatellite markers within the β-globin cluster to support robust preimplantation genetic diagnosis of β-thalassemia and sickle cell syndromes

Preimplantation genetic diagnosis (PGD) for β hemoglobinopathies has become the most common application among monogenic disorders. We present the identification of microsatellite markers [short tandem repeats (STRs)] closely linked to the β-globin gene for incorporation within PGD protocols, with the aim of increasing the number of transferable embryos. Nine candidate STRs were identified in-silico, of which three were selected based on rate-of-heterozygosity, polymerase chain reaction (PCR) efficiency and size. The multiplex reaction (β-globin gene and selected STRs, all within <0.4 Mb from the β gene) was optimized in single lymphocytes, and subsequently applied in 38 PGD cycles in couples at-risk for transmitting β hemoglobinopathies. In conclusion, incorporation of closely linked polymorphic microsatellite markers <0.4 Mb from the β-globin gene, facilitates robust assignment of β hemoglobinopathy genotypes, increasing the number of transferrable embryos otherwise rejected due to allele-drop-out (ADO), at the mutation-specific locus, compared to results based on disease-mutation genotyping alone (p < 0.001).