Selection and mutation in X-linked recessive diseases epidemiological model

To describe the epidemiology of X-linked recessive diseases we developed a discrete time, structured, non linear mathematical model. The model allows for de novo mutations (i.e. affected sibling born to unaffected parents) and selection (i.e., distinct fitness rates depending on individual's health conditions). Applying Lyapunov direct method we found the domain of attraction of model's equilibrium point and studied the convergence properties of the degenerate equilibrium where only affected individuals survive.

[Old phenotype and new genotypes. Pituitary adenomas]

Gigantism and acromegaly, usually caused by a pituitary adenoma linked inappropriate secretion of growth hormone (GH), are generally considered as very rare diseases, even if, according to some authors, their cumulative prevalence is about 1/5000. Starting from the historical case of a giant from Liège we shall describe the different types of GH pituitary adenomas and their pathophysiology. We shall particularly discuss rare forms of inherited GH secreting pituitary adenomas like the FIPA (familial inherited isolated pituitary adenomas) and the X-LAG (X linked acrogigantism), both described for the first time in Liège, in 2000 and 2014, respectively.

Mode of initial presentation and chromosomal abnormalities in Irish patients with Turner syndrome: a single-centre experience

BACKGROUND

Age at diagnosis of girls with Turner syndrome (TS) is an important indicator of successful management. We determined the age, initial clinical presentation, and chromosomal abnormalities in patients with TS.

METHODS

This was a retrospective evaluation of the clinical and laboratory records of patients with TS.

RESULTS

Sixty-five patients with TS were identified; 40 (62%) were diagnosed after age 5 years. The main presenting features were short stature, delayed puberty, dysmorphic features, and neonatal lymphoedema. Chromosomal analysis of this cohort showed that 31 patients demonstrated mosaicism, while a 45,X karyotype was observed in 19. The remaining patients had variable abnormalities including deletion, translocation, isochromosome, and ring chromosome. Y-chromosome material was found in four cases.

CONCLUSIONS

Most patients with TS were diagnosed after age 5 years, had a varied clinical presentation, and had a wide range of chromosomal abnormalities.

MicroRNA circulating in the early aftermath of motor vehicle collision predict persistent pain development and suggest a role for microRNA in sex-specific pain differences

BACKGROUND

Molecular mediators influencing the transition from acute to persistent musculoskeletal pain following common stress exposures such as motor vehicle collision (MVC) remain poorly understood. In this exploratory, proof of concept study, we compared circulating microRNA (miRNA) expression profiles in the early aftermath of MVC among individuals who did and did not subsequently develop persistent pain. Blood RNA samples were obtained from African American individuals (n = 53) who presented to the emergency department after MVC and were discharged to home after evaluation. The presence or absence of severe pain in the axial region, the most common and morbid region in which post-MVC pain occurs, was assessed 6 weeks following MVC via standardized questionnaire. miRNA expression was determined using miRNA-sequencing; nonparametric analyses were used to compare miRNA expression levels among individuals with and without persistent pain.

RESULTS

Thirty-two mature miRNA were differentially expressed (p < 0.05) in those with and without severe axial pain at 6 weeks. miR-135a-5p, a regulator of the serotonin receptor that is known to be stress-responsive, differed most significantly between groups (p = 3 × 10(-4)). This miRNA, and miR-3613-3p (p = 0.001) survived correction for multiple testing (FDR = 0.15) in this small sample. Interestingly, differentially expressed miRNA were enriched for X chromosome location. In secondary analyses, the eight X chromosome miRNA were (a) more significantly associated with axial pain in women than men, (b) expressed more highly in the peripheral blood of women than men, and (c) predicted in pathway analyses (DIANA miRPath v 2.0) to regulate neuronal and neuroendocrine pathways previously implicated in various pain pathologies.

CONCLUSIONS

These results show that circulating miRNA predict persistent severe axial pain after MVC and suggest that they may be involved in the pathogenesis of post-traumatic musculoskeletal pain. However, further studies are needed to determine if these miRNA play a direct causal role.

Klinefelter Syndrome and medical treatment: hypogonadism and beyond

Klinefelter syndrome (KS), though described more than 70 years ago, still imposes significant diagnostic challenges. Based on data from epidemiological studies, KS is associated with increased morbidity and mortality. Although the pathophysiology and etiology behind these observations are as yet not well understood, a significant contribution of hypogonadism, central to the syndrome, is traditionally suspected. However, other unknown effects inherent to the syndrome also seem to modify the disease pattern. Herein we show that KS is under-diagnosed since only roughly 25% of patients are diagnosed and the mean age of diagnosis is during adult life. KS is associated with increased morbidity resulting in loss of 2-5 years in lifespan with increased mortality from different diseases and a poor socioeconomic profile. Small testes, hypergonadothrophic hypogonadism and cognitive impairment are usually found. The accompanying hypogonadism can lead to altered body composition and a risk of developing metabolic syndrome, type 2 diabetes and cardiovascular disease. Cancer risk is generally not different from that observed in the background population, although specific cancers like breast cancer and extragonadal germ cell tumors are seen more frequently in KS. The mainstay of medical treatment is testosterone replacement therapy to both attenuate acute and long-term consequences of hypogonadism and possibly prevent the frequent comorbidity. We believe that the diagnostic challenges should be tackled more efficiently, while there is also a pressing need to generate better evidence for timing and the proper dose of testosterone replacement. We advocate for a multidisciplinary setup with the inclusion of pediatricians, speech therapists, general practitioners, psychologists, infertility specialists, urologists and endocrinologists.

Meiotic behaviour and sperm aneuploidy in an infertile man with a mosaic 45,X/46,XY karyotype

The meiotic behaviour of the germ cells in 45,X/46,XY men has not been extensively studied. This study investigated the meiotic events and sperm aneuploidy in an azoospermic man with a 45,X/46,XY (50/50) mosaic karyotype to better understand the fate of the 45,X cells and the production of chromosomally abnormal spermatozoa. Combining immunofluorescence techniques and fluorescence in-situ hybridization, meiotic recombination, synapsis, meiotic sex chromosome inactivation (MSCI) and configuration were analysed, as well as sperm aneuploidy in the patient and 10 normal, fertile men. Despite the 50:50 somatic mosaicism in the patient, 25% of pachytene cells analysed were 45,X. Furthermore, 63% of pachytene cells were 46,XY with paired sex chromosomes, and 12% were 46,XY with unpaired sex chromosomes, which displayed abnormal MCSI patterns. Although the patient's testicular spermatozoa showed increased aneuploidy, the majority were of normal constitution. The X:Y sperm ratio was significantly increased compared with the controls (P < 0.001), which may indicate that some 45,X cells gave rise to X-bearing spermatozoa. The findings provide insight into the fate of 45,X/46,XY cells in meiosis, supporting the hypothesis that stringent checkpoints ensure the favourable production of spermatozoa with normal chromosomal constitution despite an individual's abnormal karyotype.

Elucidating X chromosome influences on Attention Deficit Hyperactivity Disorder and executive function

OBJECTIVE

To identify distinct behavioral and cognitive profiles associated with ADHD in Turner syndrome (TS), relative to idiopathic ADHD and neurotypical controls, in order to elucidate X-linked influences contributing to ADHD.

METHODS

We used a multilevel-model approach to compare 49 girls with TS to 37 neurotypical females, aged 5-12, on established measures of behavior (BASC-2) and neurocognitive function (NEPSY). We further compared girls with TS to BASC-2 and NEPSY age-matched reference data obtained from children with idiopathic ADHD.

RESULTS

Within the TS group, 51% scored at or above the "at-risk" range for ADHD-associated behaviors on the BASC-2 (TS/+ADHD). The BASC-2 behavioral profile in this TS/+ADHD-subgroup was comparable to a reference group of boys with ADHD with respect to attentional problems and hyperactivity. However, the TS/+ADHD-subgroup had significantly higher hyperactivity scores relative to a reference sample of girls with ADHD (p = 0.016). The behavioral profile in TS was associated with significantly lower attention and executive function scores on the NEPSY relative to neurotypical controls (p = 0.015); but was comparable to scores from a reference sample of children with idiopathic ADHD. Deficits in attention and executive function were not observed in girls with TS having low levels of ADHD-associated behavior (TS/-ADHD).

CONCLUSIONS

ADHD-associated behavioral and cognitive problems in TS are prevalent and comparable in severity to those found in children with idiopathic ADHD. The ADHD phenotype in TS also appears relatively independent of cognitive features typically associated with TS, like visuospatial weaknesses. These findings suggest that X-linked haploinsufficiency and downstream biological effects contribute to increased risk for ADHD.

Lack of Evidence That Male Fetal Microchimerism is Present in Endometriosis

INTRODUCTION

Fetal microchimerism has been implicated in the etiology of autoimmune diseases. This study was done to test the hypothesis that male fetal microchimerism is present in eutopic and ectopic endometrium (EM) obtained from women with endometriosis but not in eutopic EM from women without endometriosis.

METHODS

A total of 31 patients were selected, including women with endometriosis (paired eutopic and ectopic EM; n = 19) and women without endometriosis (eutopic EM; n = 12). Tricolor interphase fluorescence in situ hybridization analysis was performed by cohybridization of CEP Y SpectrumAqua and CEP X SpectrumGreen (SG)/CEP Y SpectrumOrange probes.

RESULTS

Ectopic EM from women with endometriosis had 75% XX chromosomes (double SG signals) and 25% X chromosomes (single SG signal). Y chromosomes were not observed in any of the eutopic/ectopic endometrial tissues from cases or controls.

CONCLUSIONS

We were unable to confirm our hypothesis that male fetal microchimerism is present in eutopic and/or ectopic EM obtained from women with endometriosis.

X-linked acrogigantism syndrome: clinical profile and therapeutic responses

X-linked acrogigantism (X-LAG) is a new syndrome of pituitary gigantism, caused by microduplications on chromosome Xq26.3, encompassing the gene GPR101, which is highly upregulated in pituitary tumors. We conducted this study to explore the clinical, radiological, and hormonal phenotype and responses to therapy in patients with X-LAG syndrome. The study included 18 patients (13 sporadic) with X-LAG and microduplication of chromosome Xq26.3. All sporadic cases had unique duplications and the inheritance pattern in two families was dominant, with all Xq26.3 duplication carriers being affected. Patients began to grow rapidly as early as 2-3 months of age (median 12 months). At diagnosis (median delay 27 months), patients had a median height and weight standard deviation scores (SDS) of >+3.9 SDS. Apart from the increased overall body size, the children had acromegalic symptoms including acral enlargement and facial coarsening. More than a third of cases had increased appetite. Patients had marked hypersecretion of GH/IGF1 and usually prolactin, due to a pituitary macroadenoma or hyperplasia. Primary neurosurgical control was achieved with extensive anterior pituitary resection, but postoperative hypopituitarism was frequent. Control with somatostatin analogs was not readily achieved despite moderate to high levels of expression of somatostatin receptor subtype-2 in tumor tissue. Postoperative use of adjuvant pegvisomant resulted in control of IGF1 in all five cases where it was employed. X-LAG is a new infant-onset gigantism syndrome that has a severe clinical phenotype leading to challenging disease management.

Low-level 45,X/46,XX mosaicism is not associated with congenital heart disease and thoracic aorta dilatation:prospective magnetic resonance imaging and ultrasound study

OBJECTIVE

To establish the prevalence of risk factors for aortic dissection, such as bicuspid aortic valve, aortic coarctation and ascending aorta dilatation, in women with low-level 45,X/46,XX mosaicism undergoing an in-vitro fertilization (IVF) procedure.

METHODS

The study group comprised 25 women with low-level 45,X/46,XX mosaicism (ranging from 3.3% to 10.0%) who were referred to two reproductive medicine units between 2009 and 2013 because of infertility and who underwent subsequent karyotyping. In accordance with the recommendation of the Practice Committee of the American Society for Reproductive Medicine for patients with Turner syndrome (TS), prior to the IVF procedure, all women underwent careful cardiovascular screening for congenital heart disease and thoracic aorta dilatation, including standard cardiac examination, echocardiography and non-contrast cardiac magnetic resonance imaging. Aortic size index (ASI, diameter of the ascending aorta normalized to body surface area) and the prevalence of coarctation of the aorta and of bicuspid aortic valve were compared with findings previously reported in women with TS and the general population.

RESULTS

Bicuspid aortic valve without any stenosis or regurgitation was found in one woman in the study group with low-level 45,X/46,XX mosaicism, a statistically significantly lower prevalence of bicuspid aortic valve than that reported in women with TS. Aortic coarctation was not identified in any individual. The ASI was below the  95th percentile in all cases and the mean value was significantly lower than the mean reference values for both the general population and women with TS.

CONCLUSION

Compared with the general population, the prevalence of risk factors for aortic dissection was not found to be higher in women with low-level 45,X/46,XX mosaicism without any noticeable features except infertility.

Non-clear cell renal cell carcinoma, part 1: histology

Non-clear cell renal cell carcinomas (RCCs) represent up to 20% of all RCCs. Despite often being clustered as a single entity, these tumors represent a heterogeneous group of diseases with distinct molecular drivers, histologies, and clinical outcomes. Their low incidence and heterogeneity have resulted in a lack of studies that address the optimal strategies for each subtype. This article (the first in a 2-part series) reviews the histology of RCC, whereas the second article reviews current targeted therapies approved for RCC, such as the vascular endothelial growth factor receptor tyrosine kinase inhibitors and the mammalian target of rapamycin inhibitors. Ongoing studies will provide more information regarding the role of these agents in non-clear cell RCC.

Pseudocapsule of renal cell carcinoma associated with Xp11.2 translocation/TFE3 gene fusion: a clue for tumor enucleation?

OBJECTIVES

To evaluate the feasibility and efficacy of tumor enucleation (TE) for patients with small renal cell carcinoma (RCC) associated with Xp11.2 translocation/TFE3 gene fusion (Xp11.2 RCC) by analyzing the pseudocapsule characteristics of Xp11.2 RCCs comparing with that of clear cell renal cell carcinoma (ccRCC).

METHODS

From June 2007 to February 2014, 22 patients with Xp11.2 RCC who were diagnosed by fluorescence in-situ hybridization polyclonal (FISH) assay and 32 patients with ccRCC treated in our institution were comparatively studied. 12 patients with ccRCC underwent radical nephrectomy (RN) and 20 received TE. Among 22 patients with Xp11.2 RCC, 19 were treated by RN and 3 by TE (1 by radiofrequency ablation assisted TE). Pseudocapsule and other clinicopathological characteristics of the two subtypes of RCC were compared. Survival of patients treated with different surgical methods was evaluated and compared.

RESULTS

Pseudocapsule incidence of Xp11.2 RCC (14/22, 63.6%) was lower than that of ccRCC (32/32, 100%, P<0.001). However, pseudocapsule integrity rate of Xp11.2 RCC (10/14, 71.4%) was comparable with that of ccRCC (23/32, 71.9%, P=1.000). The 5-year overall survival of patients with ccRCC treated with RN and TE was 86% and 81%, respectively (P=0.845). Three patients with small Xp11.2 RCC performed well after TE.

CONCLUSIONS

Over half Xp11.2 RCC had pseudocapsules, whose integrity rate was comparable to that of ccRCC. Treatment effectives of TE and RN were comparable in ccRCC. A preliminary attempt to treat small Xp11.2 RCC with intact pseudocapsule by using TE produced a favorable treatment outcome.

X chromosome exome sequencing reveals a novel ALG13 mutation in a nonsyndromic intellectual disability family with multiple affected male siblings

X-linked intellectual disability (XLID) is a heterogeneous condition associated with mutations in >100 genes, accounting for over 10% of all cases of intellectual impairment. The majority of XLID cases show nonsyndromic forms (NSXLID), in which intellectual disability is the sole clinically consistent manifestation. Here we performed X chromosome exome (X-exome) sequencing to identify the causative mutation in an NSXLID family with four affected male siblings and five unaffected female siblings. The X-exome sequencing at 88× coverage in one affected male sibling revealed a novel missense mutation (p.Tyr1074Cys) in the asparagine-linked glycosylation 13 homolog (ALG13) gene. Segregation analysis by Sanger sequencing showed that the all affected siblings were hemizygous and the mother was heterozygous for the mutation. Recently, a de novo missense mutation in ALG13 has been reported in a patient with X-linked congenital disorders of glycosylation type I. Our study reports the first case of NSXLID caused by a mutation in ALG13 involved in protein N-glycosylation.

[Sexual dimorphism in developmental genetics]

We review the current knowledge about the molecular mechanism of sex determination and differentiation. The first sex-specific differentiation starts at the gonad, which in turns influences the development of sexual duct systems and the external genitalia. The secondary sexual characteristics in puberty complete sexual dimorphism. Recent studies have provided compelling evidence for the presence of an alternative "backdoor pathway" to produce dihydrotestosterone(DHT: the most potent androgen) directly without testosterone intermediary. This pathway primarily is operated in the normal fetal testis to produce a sufficient amount of DHT for male sex development. As for ovary development, which had formerly been regarded as a static "default" pathway, recent studies have unequivocally demonstrated that RSPO1, WNT4, and FOXL2 have important roles.

Phenotype-genotype correlations in hemophilia A carriers are consistent with the binary role of the phase between F8 and X-chromosome inactivation

BACKGROUND

The recessive X-linked disorder hemophilia A (HA) is rarely expressed in female carriers, most of whom express about half of normal factor VIII activity (

FVIII

C).

OBJECTIVE

To propose an integrative assessment model for the binary role of the phase between the mutated F8 and the active X-chromosome (Xa) in

FVIII

C in HA carriers.

METHODS

We studied 67 females at risk of severe HA, comprising five symptomatic females (

FVIII

C < 1.5 IU dL(-1) ) and 14 controls. A correlation study between

FVIII

C (observed vs. expected) and X-chromosome inactivation (XCI) patterns (XIPs; androgen receptor gene [AR] system) in blood leukocyte DNA was performed in carriers, by comparison of a model correlating

FVIII

C and XIP with arbitrary models devoid of biological significance, and with

FVIII

C levels in non-carriers (mean model) as a proxy from background data dispersion not influenced by XIP.

RESULTS

We provide proof-of-concept example from a family presenting with extremely skewed XIPs in which the severe HA phenotype appeared in a heterozygous carrier of a crossover between AR and F8 loci that phased the mutated F8 with the maternally inherited Xa. Furthermore, four cases of severe HA affected women who had a combination of a heterozygous F8 mutation and extremely skewed XIPs in leukocytes or oral mucosa are presented. Correlation analyses between

FVIII

C levels and XIPs in carriers (n = 38) but not in non-carriers (n = 20) showed highly significant differences between the proposed correlation model and models without biological significance. The data support a binary influence of XCI, either increasing or decreasing the

FVIII

C, subject to the underlying phase set between the F8 mutation and XCI.

CONCLUSIONS

Our evidence suggests that the phase between XCI and mutated F8 acts as a molecular switch conditioning

FVIII

C levels and HA expression in carriers.

Thyroid disorders in women

Thyroid disorders include autoimmune thyroid diseases (AITD), thyroid goiter, nodule and cancer. AITD mainly consist of autoimmune thyroiditis and Graves disease. The common characteristic of thyroid disorders is female preponderance in their prevalence. The female-to-male rate ratio is reported at 4~6:1 for AITD and about 3~4:1 for thyroid nodule. For PTC, it is greatest during reproductive age and drops from five and more in patients aged 20-24, to 3.4 in patients aged 35-44 to one in patients over 80. The effects of female gonadal hormones and X chromosome inactivation on thyroid gland and immune system greatly contribute to the female predilection of AITD. The former mainly include prolactin and estrogen. The direct actions of estrogen on the thyroid tissue contribute to the development of thyroid goiter, nodule and cancer in women.

Genetic mechanisms leading to primary amenorrhea in balanced X-autosome translocations

OBJECTIVE

To map the X-chromosome and autosome breakpoints in women with balanced X-autosome translocations and primary amenorrhea, searching candidate genomic loci for female infertility.

DESIGN

Retrospective and case-control study.

SETTING

University-based research laboratory.

PATIENT(S)

Three women with balanced X-autosome translocation and primary amenorrhea.

INTERVENTION(S)

Conventional cytogenetic methods, genomic array, array painting, fluorescence in situ hybridization, and quantitative reverse transcription-polymerase chain reaction.

MAIN OUTCOME MEASURE(S)

Karyotype, copy number variation, breakpoint mapping, and gene expression levels.

RESULT(S)

All patients presented with breakpoints in the Xq13q21 region. In two patients, the X-chromosome breakpoint disrupted coding sequences (KIAA2022 and ZDHHC15 genes). Although both gene disruptions caused absence of transcription in peripheral blood, there is no evidence that supports the involvement of these genes with ovarian function. The ZDHHC15 gene belongs to a conserved syntenic region that encompasses the FGF16 gene, which plays a role in female germ line development. The break in the FGF16 syntenic block may have disrupted the interaction between the FGF16 promoter and its cis-regulatory element. In the third patient, although both breakpoints are intergenic, a gene that plays a role in the DAX1 pathway (FHL2 gene) flanks distally the autosome breakpoint. The FHL2 gene may be subject to position effect due to the attachment of an autosome segment in Xq21 region.

CONCLUSION(S)

The etiology of primary amenorrhea in balanced X-autosome translocation patients may underlie more complex mechanisms than interruption of specific X-linked candidate genes, such as position effect. The fine mapping of the rearrangement breakpoints may be a tool for identifying genetic pathogenic mechanisms for primary amenorrhea.

Analysis of cell-free DNA in maternal blood in screening for fetal aneuploidies: updated meta-analysis

OBJECTIVE

To review clinical validation or implementation studies of maternal blood cell-free (cf) DNA analysis and define the performance of screening for fetal trisomies 21, 18 and 13 and sex chromosome aneuploidies.

METHODS

Searches of PubMed, EMBASE and The Cochrane Library were performed to identify all peer-reviewed articles on cfDNA testing in screening for aneuploidies between January 2011, when the first such study was published, and 4 January 2015.

RESULTS

In total, 37 relevant studies were identified and these were used for the meta-analysis on the performance of cfDNA testing in screening for aneuploidies. These studies reported cfDNA results in relation to fetal karyotype from invasive testing or clinical outcome. Weighted pooled detection rates (DR) and false-positive rates (FPR) in singleton pregnancies were 99.2% (95% CI, 98.5-99.6%) and 0.09% (95% CI, 0.05-0.14%), respectively, for trisomy 21, 96.3% (95% CI, 94.3-97.9%) and 0.13% (95% CI, 0.07-0.20) for trisomy 18, 91.0% (95% CI, 85.0-95.6%) and 0.13% (95% CI, 0.05-0.26%) for trisomy 13, 90.3% (95% CI, 85.7-94.2%) and 0.23% (95% CI, 0.14-0.34%) for monosomy X and 93.0% (95% CI, 85.8-97.8%) and 0.14% (95% CI, 0.06-0.24%) for sex chromosome aneuploidies other than monosomy X. For twin pregnancies, the DR for trisomy 21 was 93.7% (95% CI, 83.6-99.2%) and the FPR was 0.23% (95% CI, 0.00-0.92%).

CONCLUSION

Screening for trisomy 21 by analysis of cfDNA in maternal blood is superior to that of all other traditional methods of screening, with higher DR and lower FPR. The performance of screening for trisomies 18 and 13 and sex chromosome aneuploidies is considerably worse than that for trisomy 21.

TMED6-COG8 is a novel molecular marker of TFE3 translocation renal cell carcinoma

TFE3 translocation renal cell carcinoma is a highly aggressive malignancy which often occurs primarily in children and young adults. The pathognomonic molecular lesion in this subtype is a translocation event involving the TFE3 transcription factor at chromosome Xp11.2. Hence, the pathological diagnosis of an Xp11.2 translocation RCC is based upon morphology, TFE3 immunohistochemistry, or genetic analyses. However, due to the false-positive immunoreactivity for TFE3 IHC and expensive for TFE3 break-apart FISH assay, additional molecular markers are necessary to help provide early diagnose and individualization treatment. Owing to recent advances in microarray and RNA-Seq, Pflueger et al. have discovered that TMED6-COG8 is dramatically increased in TFE3 translocation RCCs, compared with clear cell RCCs and papillary RCCs, implying that TMED6-COG8 might be a new molecular tumor marker of TFE3 translocation RCCs. To extend this observation, we firstly validated the TMED6-COG8 expression level by qRT-PCR in RCCs including Xp11.2 translocation RCCs (n=5), clear cell RCCs (n=7) and papillary RCCs (n=5). Then, we also examined the expression level of TMED6-COG8 chimera in Xp11.2 translocation alveolar soft part sarcoma. We found that TMED6-COG8 chimera expression level was higher in Xp11.2 translocation RCCs than in ASPS (P<0.05). What's more, the expression levels of TMED6-COG8 chimera in esophagus cancers (n=32), gastric cancers (n=11), colorectal cancers (n=12), hepatocellular carcinomas (n=10) and non-small-cell lung cancers (n=12) were assessed. Unexpectedly, TMED6-COG8 chimera was decreased in these five human types. Therefore, our observations from this study indicated that TMED6-COG8 chimera might act as a novel diagnostic marker in Xp11.2 translocation RCCs.

African glucose-6-phosphate dehydrogenase alleles associated with protection from severe malaria in heterozygous females in Tanzania

X-linked Glucose-6-phosphate dehydrogenase (G6PD) A- deficiency is prevalent in sub-Saharan Africa populations, and has been associated with protection from severe malaria. Whether females and/or males are protected by G6PD deficiency is uncertain, due in part to G6PD and malaria phenotypic complexity and misclassification. Almost all large association studies have genotyped a limited number of G6PD SNPs (e.g. G6PD202 / G6PD376), and this approach has been too blunt to capture the complete epidemiological picture. Here we have identified 68 G6PD polymorphisms and analysed 29 of these (i.e. those with a minor allele frequency greater than 1%) in 983 severe malaria cases and controls in Tanzania. We establish, across a number of SNPs including G6PD376, that only female heterozygotes are protected from severe malaria. Haplotype analysis reveals the G6PD locus to be under balancing selection, suggesting a mechanism of protection relying on alleles at modest frequency and avoiding fixation, where protection provided by G6PD deficiency against severe malaria is offset by increased risk of life-threatening complications. Our study also demonstrates that the much-needed large-scale studies of severe malaria and G6PD enzymatic function across African populations require the identification and analysis of the full repertoire of G6PD genetic markers.

Glucose-6-phosphate dehydrogenase (G6PD) is an essential enzyme that protects red blood cells from oxidative damage. Numerous genetic variants of G6PD, residing in the X chromosome, are found among African populations: mutations causing A- deficiency can lead to serious clinical outcomes (including hemolytic anemia) but also confer protection against severe malaria. Epidemiological studies have used some of the genetic markers that cause A- deficiency to establish who is protected from severe malaria, with differing results. Whether females, with one or two copies of mutant genes, males with one copy, or both genders are protected is uncertain. This uncertainty is due to G6PD and malaria phenotypic complexity and misclassification, and to genetic differences between populations and the limited numbers of genetic markers (usually 2) considered. In this study we analysed more than 30 G6PD genetic markers in 506 Tanzanian children with severe malaria and 477 without malaria. We found that only females with one normal and one mutant copy of the gene (heterozygotes) were protected from severe malaria. Further, we established that the G6PD gene is under evolutionary pressure with the likely mechanism being selection by malaria. Our work demonstrates that studies of severe malaria and G6PD enzymatic function across African populations require, in addition to complete and accurate G6PD phenotypic classification, the identification and analysis of the full repertoire of G6PD genetic markers.

Stable X chromosome reactivation in female human induced pluripotent stem cells

In placental mammals, balanced expression of X-linked genes is accomplished by X chromosome inactivation (XCI) in female cells. In humans, random XCI is initiated early during embryonic development. To investigate whether reprogramming of female human fibroblasts into induced pluripotent stem cells (iPSCs) leads to reactivation of the inactive X chromosome (Xi), we have generated iPSC lines from fibroblasts heterozygous for large X-chromosomal deletions. These fibroblasts show completely skewed XCI of the mutated X chromosome, enabling monitoring of X chromosome reactivation (XCR) and XCI using allele-specific single-cell expression analysis. This approach revealed that XCR is robust under standard culture conditions, but does not prevent reinitiation of XCI, resulting in a mixed population of cells with either two active X chromosomes (Xas) or one Xa and one Xi. This mixed population of XaXa and XaXi cells is stabilized in naive human stem cell medium, allowing expansion of clones with two Xas.

•

Robust X chromosome reactivation in human iPSCs with large X-chromosomal deletions

•

Female human iPSCs with two active X chromosomes

•

Expansion of human iPSCs with two active X chromosomes in naive human stem cell medium

Ochratoxin A as possible factor trigging autism and its male prevalence via epigenetic mechanism

The role of dysbiosis causing leaky gut with xenobiotic production and absorption is increasingly demonstrated in autism spectrum disorder (ASD) pathogenesis. Among xenobiotics, we focused on ochratoxin A (one of the major food contaminating mycotoxin), that in vitro and in vivo exerts a male-specific neurotoxicity probably via microRNA modulation of a specific target gene. Among possible targets, we focused on neuroligin4X. Interestingly, this gene carries some single nucleotide polymorphisms (SNPs) already correlated with the disease and with illegitimate microRNA binding sites and, being located on X-chromosome, could explain the male prevalence. In conclusion, we propose a possible gene-environment interaction triggering ASD explaining the epigenetic neurotoxic mechanism activated by ochratoxin A in genetically predisposed children. This mechanism offers a clue for male prevalence of the disease and may have an important impact on prevention and cure of ASD.

[Acute promyelocytic leukaemia with translocations of t(15;17)(q22;q21) and rob(13;21): a case report and literatures review]

OBJECTIVE

To report an acute promyelocytic leukaemia (APL) case with translocation of rob (13;21) t(15;17) (q22;q21) and review its clinical and laboratory characteristics.

METHODS

Based on routine karyotype analysis and bone marrow morphology, we further used double color double fluorescent in situ hybridization (DCDF-FISH) and reverse transcriptase PCR (RT-PCR) to examine the patient's abnormities on cytogenetic and molecular biology, and reveal the clinical characteristics of this rare translocation also from the related literatures.

RESULTS

The clinical manifestation and bone marrow morphology examination of this patient were in accordance with pathologic feature of APL. On first visit, immunophenotyping analysis showed positive myeloid markers. Through R-banding, the patient's karyotype was confirmed as 45, XX, rob(13;21) t(15;17) (q22;q21) [6]/45, XX, rob(13;21) [14]. FISH results showed that 68.9% cells were typical t(15;17) pattern. The positive rates of fusion gene of PML-RARα detected by RT-PCR was 25.8%. Patient was treated by induction and consolidation therapy, the karyotype was 45, XX, rob(13;21 )[20] after complete remission. The positive rate of fusion gene of PML-RARα by FISH and its level were 2.5% and 0.003% respectively.

CONCLUSION

APL with rob (13;21) t(15;17) (q22;q21) was very rare, which was accorded with clinical and laboratory characteristics of APL. The value of chromosome abnormality as a prognostic marker in APL needs to be further observed..