X Chromosome Inactivation Pattern and Pregnancy Outcome of Female Carriers of Pathogenic Heterozygous X-Linked Deletions

Prenatal risk assessment of carriers of heterozygous X-linked deletion is a big challenge due to the phenotypic modification induced by X chromosome inactivation (XCI). Herein, we described four Chinese pedigrees with maternal-inherited X-deletions above 1 Mb. The pathogenic evaluation revealed that all X-deletions are harmful to heterozygous carriers; however, the asymptomatic pregnant female carriers in these families tremendously complicate the prognostic assessment of the unborn heterozygous embryos. In this study, we detected the XCI pattern of 11 female carriers of heterozygous X-linked deletions and 4 non-carrier females in these families and performed the first prenatal XCI pattern analysis in a fetal female carrier of heterozygous PCDH19-deletion to make risk prediction. In an adult female who lost one copy of the terminal of X chromosome short arm (Xp), a region enriching a large number of XCI escapees, the expression level of representative XCI escape genes was also detected. Pregnancy outcomes of all families were followed up or retrospected. Our research provides clinical evidence that X-deletions above 1 Mb are indeed associated with extremely skewed XCI. The favorable skewed XCI in combination with potential compensatory upregulation of XCI escapees would protect some but not all female carriers with pathogenic X-deletion from severe clinical consequences, mainly depending on the specific genetic contents involved in the deletion region. For PCDH19-disorder, the XCI pattern is considered as the decisive factor of phenotype expression, of which prenatal XCI assay using uncultured amniocytes could be a practicable way for risk prediction of this disease. These results provide valuable information about the usage of XCI assay in the prenatal risk assessment of heterozygous X-linked deletions.

Determining common variants in patients with haemophilia A in South Vietnam and screening female carriers in their family members

AimsThe aim of this study was to determine common variants in F8, including intron 22 inversion (Inv22), intron 1 inversion (Inv1) and point mutations, the transmission of these variants between patients with haemophilia A (HA) and their family members.MethodsGenetic analysis was conducted in 71 patients who were clinically diagnosed with HA and 152 related female members in South Vietnam by a combination of inversion PCR (I-PCR), multiplex PCR and direct sequencing.ResultsVariants in F8, including Inv22, point mutations (with 37 genotypes) and two novel variants, occupied 60 patients with HA. Among severe patients, the rate of Inv22 was 44%. Missense was the common point mutation of over 50% in patients with moderate HA and mild HA. Inv1 was absent in all patients. F8 variants were also found in 119 female carriers (FCs) (78.3%) from families related to patients with HA. There were 56 mothers (93.3%) carrying F8 variants and passing the same variants to their sons.ConclusionsThese findings were the first to provide important information about the presence of Inv22 and point mutation in Vietnamese patients with HA, the mothers and their female family members. It demonstrated that genetic diagnosis and counselling for HA carriers were essential factors for future improvements in comprehensive and equitable healthcare polices for patients with HA and FCs in Vietnam.

Identification of a novel RPGR mutation associated with X-linked cone-rod dystrophy in a Chinese family

Background Cone-rod dystrophy (CORD) is a group of inherited retinal dystrophies, characterized by decreased visual acuity, color vision defects, photophobia, and decreased sensitivity in the central visual field. Our study has identified a novel pathogenic variant associated with X-linked cone-rod dystrophy (XLCORD) in a Chinese family. Methods All six family members, including the proband, affected siblings, cousins and female carriers, have underwent thorough ophthalmic examinations. The whole exome sequencing was performed for the proband, followed by Sanger sequencing for spilt-sample validation. A mammalian expression vector (AAV-MCS) with mutated retinitis pigmentosa GTPase regulator (RPGR) sequence was expressed in HEK293 T cells. The mutated protein was verified by Western blotting and immunohistochemistry. Results A novel mutation in the RPGR gene (c.2383G > T, p.E795X) is identified to be responsible for CORD pathogenesis. Conclusions Our findings have expanded the spectrum of CORD-associated mutations in RPGR gene and serve as a basis for genetic diagnosis for X-linked CORD.

Germline PALB2 Variants and PARP Inhibitors in Endometrial Cancer

PARP inhibitors are orally administered antineoplastic agents that affect the homologous recombination (HR) repair pathway, and are approved by the FDA for the treatment of ovarian, breast, pancreatic, and prostate cancers. This report presents a case of recurrent endometrial carcinoma occurring in a woman with a germline pathogenic PALB2 whole-exon deletion. This uncommon finding in a patient with endometrial carcinoma provided the opportunity to use a management strategy of PARP inhibition with olaparib, resulting in a prolonged response to treatment; however, disease progression eventually occurred. Further studies are required to elucidate the mechanisms underlying resistance to PARP inhibition, and the potential future treatment options in this setting. Current recommendations for risk management of female carriers of PALB2 variants focus on breast and ovarian cancer risk. This case raises the additional question of a potential role for risk-reducing hysterectomy in female carriers of PALB2 variants.

A maternally inherited Interstitial Xq21 deletion associated with deafness and mental retardation syndrome in a male patient

Клиническое значение делеции района q21 хромосомы X у мужчин все еще плохо изучено. Было показано, что делеция Xq21, включающая гены POU3F4, CHM и ZNF711, может приводить к глухоте, умственной отсталости и хороидеремии. Несмотря на тяжелые симптомы, наблюдаемые у пробандов-мужчин, большинство носителей женского пола бессимптомны или имеют незначительные фенотипические проявления. Представлена клиническая и молекулярно-цитогенетическая характеристика случая делеции района q21.1-q21.31 хромосомы X, выявленной при проведении хромосомного микроматричного анализа у пациента с задержкой психоречевого развития, лицевыми дизморфиями и тугоухостью. Такая же делеция была выявлена у практически здоровой матери. Наши данные способствуют дальнейшему пониманию корреляции между делецией Xq21 и аномальным фенотипом. Deletions on the X chromosome can lead to serious birth defects. Deletions in Xq21 cause various congenital defects in males including choroideremia, deafness and mental retardation, depending on their size and gene content. Only a limited number of patients with Xq21 deletions has been reported. It has been shown that deletions of the adjacent Xq21 genes, including the POU3F4, CHM and ZNF711 genes, can lead to deafness and mental retardation syndrome and choroideremia. Despite the severe symptoms exhibited by male probands, most female carriers are asymptomatic or exhibit only a mild phenotype. The article presents the clinical and molecular-cytogenetic characteristics of a case of deletion of the Xq21.1-q21.31 region of chromosome X, revealed during chromosomal microarray analysis in a patient with delayed psycho-speech development, facial dysmorphisms and hearing loss. The same deletion was found in an apparently healthy mother. Our study confirms the causative effect between the Xq21 deletion in males and choroideremia, deafness and mental retardation.

Rare Co-Occurrence of Visual Snow in a Female Carrier With RPGRORF15-Associated Retinal Disorder

X-linked retinitis pigmentosa (XLRP), a rare form of retinitis pigmentosa (RP), is predominantly caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. Affected males often present with severe phenotypes and early disease onset. In contrast, female carriers are usually asymptomatic or show stationary phenotypes. Herein, we reported an 8-year-old female carrier, a daughter of a confirmed RP father with RPGR mutation, with an early onset of progressive cone-rod pattern retinal dystrophy. Additionally, the carrier experienced visual snow-like symptom as long as she recalled. Ophthalmological examination showed the reduction of visual acuity and attenuation of photoreceptor functions since the age of 5 years. Further analysis revealed a heterozygous pathogenic variant of the RPGR gene and a random X-inactivation pattern. Although she harboured an identical RPGR variant as the father, there were phenotypic intrafamilial variations. The information on the variety of genotypic and phenotypic presentations in XLRP carriers is essential for further diagnosis, management, and monitoring of these cases, including the design of future gene therapy trials.

Survival analysis in hypertrophic cardiomyopathy caused by the three most common pathogenic TPM1 variants

Purpose To evaluate survival free of cardiovascular events in carriers of the three most frequent TPM1 pathogenic hypertrophic cardiomyopathy (HCM) variants. Methods Clinical and genetic data on families carrying TPM1 variants in the literature and identified in our center were systematically revised and collected in a database. Classification of variant's pathogenicity was in accordance with ACMG criteria. We evaluated available follow-up data and constructed Kaplan-Meier survival curves to cardiovascular death (sudden death, appropriate cardiodefibrillator shock, heart failure death, and stroke-related death) or heart transplant. Long-rank test was used to compare event-free survival time. Results 562 carriers (343 HCM-probands and 219 relatives; 51.3% male carriers) were identified carrying 73 missense variants considered disease causing. TPM1 p.Asp175Asn (87 probands, 109 relatives, 6 unaffected), p.Arg21Leu (52 probands, 25 relatives, 16 unaffected), and p.Met281Val (37 probands, 8 relatives, 9 unaffected) were the most prevalent HCM-variants. Among these three variants, survival data was reported for 508 individuals. Eight-nine carriers had suffered events: 74 sudden deaths (55% males), nine heart failure deaths (44% males), two transplants (50% males), and five stroke-related death (25% males). Incidence of cardiovascular death or transplant was similar between TPM1 p.Arg21Leu and p.Met281Val (p=0.75) and different than p.Asp175Asn (p=0.03 and p=0.06, respectively) and all TPM1 variants (p=0.004 and p=0.04). Analysis by sex showed TPM1 p.Arg21Leu female carriers had better prognosis than p.Asp175Asn male carriers (p=0.048) and all TPM1 male and female carriers (p=0.02 and p=0.04) (curves not showed in the graph). Conclusion TPM1 p.Arg21Leu and p.Met281Val could have a better prognosis than p.Asn175Asn and all other TPM1 missense variants in HCM. No marked difference was observed between male and female carriers. More than 80% of the events were arrhythmic deaths. FUNDunding Acknowledgement Type of funding sources: Private company. Main funding source(s): HEALTH IN CODE SL

What is the threshold of mature oocytes to obtain at least one healthy transferable cleavage-stage embryo after preimplantation genetic testing for fragile X syndrome?

STUDY QUESTION What are the chances of obtaining a healthy transferable cleavage-stage embryo according to the number of mature oocytes in fragile X mental retardation 1 (FMR1)-mutated or premutated females undergoing preimplantation genetic testing (PGT)? SUMMARY ANSWER In our population, a cycle with seven or more mature oocytes has an 83% chance of obtaining one or more healthy embryos. WHAT IS KNOWN ALREADY PGT may be an option to achieve a pregnancy with a healthy baby for FMR1 mutation carriers. In addition, FMR1 premutation is associated with a higher risk of diminished ovarian reserve and premature ovarian failure. The number of metaphase II (MII) oocytes needed to allow the transfer of a healthy embryo following PGT has never been investigated. STUDY DESIGN, SIZE, DURATION The study is a monocentric retrospective observational study carried out from January 2006 to January 2020 that is associated with a case-control study and that analyzes 38 FMR1 mutation female carriers who are candidates for PGT; 16 carried the FMR1 premutation and 22 had the full FMR1 mutation. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 95 controlled ovarian stimulation (COS) cycles for PGT for fragile X syndrome were analyzed, 49 in premutated patients and 46 in fully mutated women. Only patients aged ≤38 years with anti-Müllerian hormone (AMH) >1 ng/ml and antral follicle count (AFC) >10 follicles were eligible for the PGT procedure. Each COS cycle of the FMR1-PGT group was matched with the COS cycles of partners of males carrying any type of translocation (ratio 1:3). Conditional logistic regression was performed to compare the COS outcomes. We then estimated the number of mature oocytes needed to obtain at least one healthy embryo after PGT using receiver operating characteristic curve analysis. MAIN RESULTS AND THE ROLE OF CHANCE Overall, in the FMR1-PGT group, the median number of retrieved and mature oocytes per cycle was 11 (interquartile range 7–15) and 9 (6–12), respectively. The COS outcomes of FMR1 premutation or full mutation female carriers were not altered compared with the matched COS cycles in partners of males carrying a balanced translocation in their karyotype. Among the 6 (4–10) Day 3 embryos obtained in the FMR1-PGT group, a median number of 3 (1–6) embryos were morphologically eligible for biopsy, leading to 1 (1–3) healthy embryo. A cutoff value of seven MII oocytes yielded a sensitivity of 82% and a specificity of 61% of having at least one healthy embryo, whereas a cutoff value of 10 MII oocytes led to a specificity of 85% and improved positive predictive value. LIMITATIONS, REASONS FOR CAUTION This study is retrospective, analyzing a limited number of cycles. Moreover, the patients who were included in a fresh PGT cycle were selected on ovarian reserve parameters and show high values in ovarian reserve tests. This information could influence our conclusion. WIDER IMPLICATIONS OF THE FINDINGS The results relate only to the target population of this study, with a correct ovarian reserve of AMH >1 and AFC >10. However, the information provided herein extends knowledge about the current state of COS for FMR1 mutation carriers in order to provide patients with proper counseling regarding the optimal number of oocytes needed to have a chance of transferring an unaffected embryo following PGT. STUDY FUNDING/COMPETING INTEREST(S) None. TRIAL REGISTRATION NUMBER N/A.

Functional Analysis of Ectodysplasin-A Mutations in X-Linked Nonsyndromic Hypodontia and Possible Involvement of X-Chromosome Inactivation

Background. Mutations of the Ectodysplasin-A (EDA) gene are generally associated with syndrome hypohidrotic ectodermal dysplasia or nonsyndromic tooth agenesis. The influence of EDA mutations on dentinogenesis and odontoblast differentiation has not been reported. The aim of this study was to identify genetic clues for the causes of familial nonsyndromic oligodontia and explore the underlying mechanisms involved, while focusing on the role of human dental pulp stem cells (hDPSCs). Materials and Methods. Candidate gene sequences were obtained by PCR amplification and Sanger sequencing. Functional analysis was conducted, and the pathogenesis associated with EDA mutations in hDPSCs was investigated to explore the impact of the identified mutation on the phenotype. Capillary electrophoresis (CE) was used to detect X-chromosome inactivation (XCI) in the blood of female carriers. Results. In this study, we identified an EDA mutation in a Chinese family: the missense mutation c.1013C>T (Thr338Met). Transfection of hDPSCs with a mutant EDA lentivirus decreased the expression of EDA and dentin sialophosphoprotein (DSPP) compared with transfection of control EDA lentivirus. Mechanistically, mutant EDA inhibited the activation of the NF-κB pathway. The CE results showed that symptomatic female carriers had a skewed XCI with a preferential inactivation of the X chromosome that carried the normal allele. Conclusions. In summary, we demonstrated that EDA mutations result in nonsyndromic tooth agenesis in heterozygous females and that, mechanistically, EDA regulates odontogenesis through the NF-κB signalling pathway in hDPSCs. Due to the large heterogeneity of tooth agenesis, this study provided a genetic basis for individuals who exhibit similar clinical phenotypes.

The Influence of Sex on Embryo Development and Pregnancy Outcome in Preimplantation Genetic Testing for Chromosomal Translocation

Background To investigate the embryonic development and clinical pregnancy outcome of reciprocal translocation carriers and Robertsonian translocation carriers with different sex in preimplantation genetic testing (PGT). Methods A retrospective analysis of 1369 cycles of preimplantation genetic testing for structural rearrangements (PGT-SR) was performed in the Reproductive Medicine Center of the First Affiliated Hospital of Zhengzhou University from 2015 to 2019. All the patients were divided into reciprocal translocation and Robertsonian translocation according to the type of chromosomal translocation and divided into female carriers and male carriers according to the sex of the carriers. SPSS21.0 was used for data statistics and P < 0.05 indicated that the difference was statistically significant. Results The fertilization rate of female carriers(81.5%) with chromosomal structural abnormalities (including reciprocal translocation and Robertsonian translocation) was higher than that of male carriers(80.0%)(P=0.032), and the blastocyst formation rate of female carriers(50.0%) was lower than that of male carriers(54.8%)(P=0.016) in the same parental age. But there was no statistical difference in cleavage rate, high quality embryo rate, normal rate of biopsy, clinical pregnancy rate, abortion rate and live birth rate between female and male carriers. In the reciprocal translocation group, the blastocyst formation rate of male carriers (54.8%) was higher than that of female carriers (50.0%) (P=0.022) with the same parental age and there was no difference in pregnancy outcome. In the Robertsonian translocation group, the fertilization rate of male carriers (75.0%) was lower than that of female carriers (81.8%) (P=0.005) and the normal rate of biopsy (33.3%) was higher than that of female carriers (25.0%) (P=0.022) with the same parental age and there was no difference in pregnancy outcome. Conclusions In reciprocal translocation, male carriers have a higher rate of blastocyst formation rate than female carriers. In Robertsonianian translocation, male carriers have a higher noamal rate of biopsy than female carriers. However, there was no significant difference in pregnancy outcome between male carriers and female carriers with abnormal chromosome structure.