Role of Skewed X-Chromosome Inactivation in Common Variable Immunodeficiency.

The term common variable immunodeficiency (CVID) encompasses a clinically diverse group of disorders, mainly characterized by hypogammaglobulinemia, insufficient specific antibody production, and recurrent infections. The genetics of CVID is complex, and monogenic defects account for only a portion of cases, typically <30%. Other proposed mechanisms include digenic, oligogenic, or polygenic inheritance and epigenetic dysregulation. In this study, we aimed to assess the role of skewed X-chromosome inactivation (XCI) in CVID. Within our cohort of 131 genetically analyzed CVID patients, we selected female patients with rare variants in CVID-associated genes located on the X-chromosome. Four patients harboring heterozygous variants in BTK (n = 2), CD40LG (n = 1), and IKBKG (n = 1) were included in the study. We assessed XCI status using the HUMARA assay and an NGS-based method to quantify the expression of the 2 alleles in mRNA. Three of the 4 patients (75%) exhibited skewed XCI, and the mutated allele was predominantly expressed in all cases. Patient 1 harbored a hypomorphic variant in BTK (p.Tyr418His), patient 3 had a pathogenic variant in CD40LG (c.288+1G>A), and patient 4 had a hypomorphic variant in IKBKG (p.Glu57Lys) and a heterozygous splice variant in TNFRSF13B (TACI) (c.61+2T>A). Overall, the analysis of our cohort suggests that CVID in a small proportion of females (1.6% in our cohort) is caused by skewed XCI and highly penetrant gene variants on the X-chromosome. Additionally, skewed XCI may contribute to polygenic effects (3.3% in our cohort). These results indicate that skewed XCI may represent another piece in the complex puzzle of CVID genetics.

Preferential X Chromosome Inactivation as a Mechanism to Explain Female Preponderance in Myasthenia Gravis.

Myasthenia gravis (MG) is a neuromuscular autoimmune disease characterized by prevalence in young women (3:1). Several mechanisms proposed as explanations for gender bias, including skewed X chromosome inactivation (XCI) and dosage or sex hormones, are often involved in the development of autoimmunity. The skewed XCI pattern can lead to an unbalanced expression of some X-linked genes, as observed in several autoimmune disorders characterized by female predominance. No data are yet available regarding XCI and MG. We hypothesize that the preferential XCI pattern may contribute to the female bias observed in the onset of MG, especially among younger women. XCI analysis was performed on blood samples of 284 women between the ages of 20 and 82. XCI was tested using the Human Androgen Receptor Assay (HUMARA). XCI patterns were classified as random (XCI < 75%) and preferential (XCI ≥ 75%). In 121 informative patients, the frequency of skewed XCI patterns was 47%, significantly higher than in healthy controls (17%; p ≤ 0.00001). Interestingly, the phenomenon was observed mainly in younger patients (<45 years; p ≤ 0.00001). Furthermore, considering the XCI pattern and the other clinical characteristics of patients, no significant differences were found. In conclusion, we observed preferential XCI in MG female patients, suggesting its potential role in the aetiology of MG, as observed in other autoimmune diseases in women.

Improved HUMARA for the Detection of X-Linked Agammaglobulinemia Carriers.

Background: Fragment analysis of exon 1 of the human androgen receptor, known as HUMARA, is a polymerase chain reaction (PCR)-based method for detecting X-linked agammaglobulinemia (XLA) carriers. This method takes advantage of X-chromosome inactivation (XCI) in female cells. XLA is caused by mutations in the Bruton tyrosine kinase (BTK) gene, located in Xq22.1. In this study, XCI is nonrandom or skewed in B-cells. B-cells with an active X-chromosome carrying a BTK mutation do not mature. Peripheral B-cells in XLA carriers inactivate the mutated X-chromosome. Methods: HUMARA was performed using DNA from purified B-cells and total leukocytes. DNA was digested using methylation-sensitive HhaI. The PCR of the HUMARA polymorphic marker was performed with the HhaI digested samples. The lengths of the PCR products were determined. If a suspected carrier showed skewed XCI in their B-cells, the marker length that corresponded with the length determined in the index patient indicated their carrier status. Results: HUMARA was conducted on purified B-cells; this allowed easier identification of the mutated or inactive allele, as the active allele was enzymatically digested. Analysis of 30 possible carriers using modified HUMARA corroborated that the carrier status in all samples that were heterozygous for the marker using XCI calculation for leukocytes showed a Gaussian distribution, while the carrier B-cell DNA showed a skewed XCI. Conclusion: Carrier status was successfully determined for most of the analyzed samples. B-cell enrichment resulted in precise carrier determination data, reduced the sample size, and facilitated inactive and active allele identification.

Use of the FMR1 Gene Methylation Status to Assess the X-Chromosome Inactivation Pattern: A Stepwise Analysis.

X-chromosome inactivation (XCI) is a developmental process to compensate the imbalance in the dosage of X-chromosomal genes in females. A skewing of the XCI pattern may suggest a carrier status for an X-linked disease or explain the presence of a severe phenotype. In these cases, it is important to determine the XCI pattern, conventionally using the gold standard Human Androgen-Receptor Assay (HUMARA), based on the analysis of the methylation status at a polymorphic CAG region in the first exon of the human androgen receptor gene (AR). The aim of this study was to evaluate whether the methylation status of the fragile mental retardation protein translational regulator gene (FMR1) can provide an XCI pattern similar to that obtained by HUMARA. A set of 48 female carriers of FMR1 gene normal-sized alleles was examined using two assays: HUMARA and a FMR1 methylation PCR (mPCR). Ranges were defined to establish the XCI pattern using the methylation pattern of the FMR1 gene by mPCR. Overall, a 77% concordance of the XCI patterns was obtained between the two assays, which led us to propose a set of key points and a stepwise analysis towards obtaining an accurate result for the XCI pattern and to minimize the underlying pitfalls.

Papel de la activación adicional del gen RA en el desarrollo del fenotipo resistente a la castración en el cáncer de próstata / Additional activation of the AR gene may be involved in the development of the castration resistance phenotype in prostate cancer

Introducción Diversos estudios han demostrado que los cambios en el gen RA pueden estar asociados a un fenotipo de enfermedad más agresivo e incluso al cáncer de próstata resistente a la castración. Por este motivo, hemos investigado las alteraciones citogénicas y moleculares asociadas al RA.Materiales y métodos Para evaluar la metilación del RA, realizamos un análisis citogenético-molecular mediante hibridación fluorescente in situ que utiliza sondas específicas para el gen del RA (Xq11.12) y el centrómero del cromosoma X. Respecto a la actividad del RA, realizamos un análisis cualitativo de la actividad del receptor de andrógenos humano. Para analizar la expresión del RA en las líneas celulares PC3 y LNCaP, utilizamos ensayos de qPCR.ResultadosEn el ensayo qPCR, encontramos una regulación a la baja del RA en la línea celular PC3 en comparación con la LNCaP. Hallamos la presencia de polisomía del cromosoma X en las líneas celulares PC-3 y LNCaP mediante el ensayo FISH. En el ensayo HUMARA-Q encontramos la presencia de dos cromosomas X/célula y actividad en ambos RA de la línea celular PC-3. En las células LNCaP hallamos la presencia de dos cromosomas X/célula y la metilación de solo un RA.Conclusión El fenotipo del cáncer de próstata resistente a la castración representa un gran desafio en el tratamiento urológico. Estos cromosomas X y las alteraciones ligadas al RA pueden contribuir a una mejor comprensión de la enfermedad; sin embargo, deben realizarse más estudios para arrojar más luz sobre el papel del RA en el fenotipo del cáncer de próstata resistente a la castración (AU)

Introduction Several studies have already shown that changes in the AR gene may be associated with a more aggressive disease phenotype and even castration-resistant prostate cancer. Thus, we investigated cytogenetic and molecular alterations linked to AR.Materials and methods To evaluate AR methylation, we performed a cytogenetic-molecular analysis using fluorescence in situ hybridization that uses specific probes for the AR gene (Xq11.12) and the X chromosome centromere. For AR activity, we performed a qualitative analysis of human androgen receptor activity. To analyze the expression of AR in PC3 and LNCaP cell lines, we used qPCR assays.ResultsIn the qPCR assay, we found downregulation of AR in the PC3 cell line compared with the LNCaP. We found the presence of X chromosome polysomy in PC-3 and LNCaP cell lines by FISH assay. In the HUMARA-Q assay, we found two X chromosomes/cell and the activity of both AR in the PC-3 cell line. In LNCaP cells, we found two X chromosomes/cell and methylation of only one AR.Conclusion Castration-resistant prostate cancer phenotype represents a significant challenge in the setting of urological management. The X chromosomes and AR-linked alterations may contribute to a better understanding of the disease. However, further studies should be performed in an attempt to elucidate as much as possible the role of AR in the castration-resistant prostate cancer phenotype (AU)

Additional activation of the AR gene may be involved in the development of the castration resistance phenotype in prostate cancer.

INTRODUCTION: Several studies have already shown that changes in the AR gene may be associated with a more aggressive disease phenotype and even castration-resistant prostate cancer. Thus, we investigated cytogenetic and molecular alterations linked to AR. MATERIALS AND METHODS: To evaluate AR methylation, we performed a cytogenetic-molecular analysis using fluorescence in situ hybridization that uses specific probes for the AR gene (Xq11.12) and the X chromosome centromere. For AR activity, we performed a qualitative analysis of human androgen receptor activity. To analyze the expression of AR in PC3 and LNCaP cell lines, we used qPCR assays. RESULTS: In the qPCR assay, we found downregulation of AR in the PC3 cell line compared with the LNCaP. We found the presence of X chromosome polysomy in PC-3 and LNCaP cell lines by FISH assay. In the HUMARA-Q assay, we found two X chromosomes/cell and the activity of both AR in the PC-3 cell line. In LNCaP cells, we found two X chromosomes/cell and methylation of only one AR. CONCLUSION: Castration-resistant prostate cancer phenotype represents a significant challenge in the setting of urological management. The X chromosomes and AR-linked alterations may contribute to a better understanding of the disease. However, further studies should be performed in an attempt to elucidate as much as possible the role of AR in the castration-resistant prostate cancer phenotype.

X-chromosome inactivation patterns in females with Fabry disease examined by both ultra-deep RNA sequencing and methylation-dependent assay.

BACKGROUND: Fabry disease is an X-linked inherited lysosomal storage disorder caused by mutations in the gene encoding α-galactosidase A. Males are usually severely affected, while females have a wide range of disease severity. This variability has been assumed to be derived from organ-dependent skewed X-chromosome inactivation (XCI) patterns in each female patient. Previous studies examined this correlation using the classical methylation-dependent method; however, conflicting results were obtained. This study was established to ascertain the existence of skewed XCI in nine females with heterozygous pathogenic variants in the GLA gene and its relationship to the phenotypes. METHODS: We present five female patients from one family and four individual female patients with Fabry disease. In all cases, heterozygous pathogenic variants in the GLA gene were detected. The X-chromosome inactivation patterns in peripheral blood leukocytes and cells of urine sediment were determined by both classical methylation-dependent HUMARA assay and ultra-deep RNA sequencing. Fabry Stabilization Index was used to determine the clinical severity. RESULTS: Skewed XCI resulting in predominant inactivation of the normal allele was observed only in one individual case with low ⍺-galactosidase A activity. In the remaining cases, no skewing was observed, even in the case with the highest total severity score (99.2%). CONCLUSION: We conclude that skewed XCI could not explain the severity of female Fabry disease and is not the main factor in the onset of various clinical symptoms in females with Fabry disease.

Genetic analysis for carrier diagnosis in hemophilia A and B in the Mexican population: 25 years of experience.

Our 25 years of experience in carrier diagnosis of hemophilia A (HA) and B (HB) in Mexican population comprises linkage analysis of intragenic F8/F9 neutral variants along with, in severe HA (SHA), detection of F8 int22h and int1h inversions. In symptomatic carriers (SCs) we explored Lyonization to explain their symtomatology. From a DNA-Bank of 3,000 samples, intragenic restriction fragment length (RFLPs) and short tandem repeats (STRs) of F8/F9 genes were assessed by PCR-PAGE and GeneScan. In SHA patients, F8 inversions were detected by inverse shifting-PCR/diagnostic and complementary tests. In SCs, we evaluated hemorrhagic symptoms, clotting FVIII/FIX and X-chromosome inactivation (XCI) patterns were assessed by HUMARA assay and the search of XIST promoter pathogenic variants. Informativeness of linkage analysis for HA carrier diagnosis with RFLP's/STR's increased to 74% and reached 80% with five RFLPs for HB. Combined Inv22/Inv1 diagnosed 113 possible carriers, three de novo Inv22-1, and confirmed 45 mothers as obligate or sporadic carriers. Among 21 SCs, four showed extreme skewed XCI pattern (~80:20) but had normal karyotype and no C43G pathogenic variant in XIST promoter. Clotting FVIII/FIX correlated with the active X in leukocytes. Our data integrate the largest comprehensive research worldwide on the molecular diagnosis of HA and HB carriers in terms of the number of studied and diagnosed cases, in addition to the genetic analysis in SCs. Intragenic RFLPs and STRs of F8/F9 genes along with F8 int22h/int1h inversions in SHA emerge as optimal variants for molecular diagnosis in Mexican population. In counseling SCs, inheritance of skewed X-inactivation should be considered.

Heterozygous Deletion of the SHOX Gene Enhancer in two Females With Clinical Heterogeneity Associating With Skewed XCI and Escaping XCI.

Skewed X-chromosome inactivation (XCI) plays an important role in the phenotypic heterogeneity of X-linked disorders. However, the role of skewed XCI in XCI-escaping gene SHOX regulation is unclear. Here, we focused on a heterozygous deletion of SHOX gene enhancer with clinical heterogeneity. Using SNP array, we detected that the female proband with Leri-Weill dyschondrosteosis (LWD) carried an 857 kb deletion on Xp22.3 (encompassing SHOX enhancer) and a 5,707 kb large-fragment deletion on Xq25q26. XCI analysis revealed that the X-chromosome with the Xq25q26 large-fragment deletion was completely inactivated, which forced the complete activation of the other X-chromosome carrying SHOX enhancer deletion. While the Xp22.3 deletion locates on the escaping XCI region, under the combined action of skewed XCI and escaping XCI, transcription of SHOX gene was mainly from the activated X-chromosome with SHOX enhancer defect, involving in the formation of LWD phenotype. Interestingly, this SHOX enhancer deletion was inherited from her healthy mother, who also demonstrated completely skewed XCI. However, the X-chromosome with SHOX enhancer deletion was inactivated, and the normal X-chromosome was activated. Combing with escaping XCI, her phenotype was almost normal. In summary, this study was a rare report of SHOX gene enhancer deletion in a family with clinical heterogeneity due to skewed inactivation of different X-chromosomes, which can help in the genetic counseling and prenatal diagnosis of disorders in females with SHOX defect.

Clonality analysis of multifocal ipsilateral breast carcinomas using X-chromosome inactivation patterns.

The definition of multifocal breast cancer is ambiguous, and its incidence varies depending on the definition and detection methods. Multifocal breast cancers either have the same clonal origin or arise from completely distinct progenitor cells. The current American Joint Committee on Cancer Staging system and College of American Pathologists breast tumor guidelines state that only the largest tumor needs to be staged and studied immunohistochemically, on the assumption that they are of the same origin. However, some multifocal tumors have been proved to have arisen from different clones. In the present study, 71 cases of surgically resected multifocal breast cancers were selected. To detect and characterize the tumors of each clonal origin, a human androgen receptor gene (HUMARA) assay to compare the X-chromosome inactivation patterns of multiple tumors was conducted. Twenty-nine of 71 (40.8%) patients were revealed to be heterozygous for HUMARA. Sixty-four (90.1%) patients had the same X chromosome inactivated in different tumors. Seven (9.9%) cases had different inactivated X chromosomes between multifocal tumors, indicating that those tumors were from separate progenitor cells. Five (7.0%) cases showed identical histologic features but had different inactivated HUMARA alleles. According to these results, 2 separate tumors might be synchronous primary tumors, although their histopathologic characteristics are similar. Furthermore, multifocal tumors can be of different origins despite being closely located to each other. These findings suggest that separate grouping of multiple breast tumors based on their clonal origin is needed for future studies.

Molecular analysis of ovarian mucinous carcinoma reveals different cell of origins.

It is believed that a subset of primary ovarian mucinous tumors is derived from mature teratomas [1-5]. To confirm this, we performed microsatellite genotyping using a variety of short tandem repeat makers and analyzed allelotypes of 8 mucinous tumors (4 mucinous carcinomas, 3 atypical proliferative mucinous tumors and 1 mucinous cystadenoma) associated with a teratoma to determine whether they were clonally related. 7 of the 8 mucinous tumors showed complete or a high degree of homozygosity. Among the 6 pairs of tumors with teratoma tissue available for comparison, 5 of 6 showed a high or complete degree of allelotypes matching, which differed from the somatic allelotypes of the normal control tissue. A discrepancy was detected between carcinoma and teratoma in one pair at several loci, with different X-chromosome inactivation patterns revealed by the HUMARA clonality assay. We also investigated the allelotypes of 16 ovarian mucinous carcinomas without a teratoma in young patients (range 13-30) and in 6 older patients (range 40-67) using the same method. None of these tumors showed pure homozygosity. The number of homozygous loci in this cohort was significantly lower than that in the first. Our results suggest first, that most mucinous tumors associated with a teratoma are derived from the teratoma but occasionally they could be collision tumors and second that the majority of pure mucinous tumors in young women in whom a teratoma is not present are not derived from a teratoma.

Clonality analysis of combined Brenner and mucinous tumours of the ovary reveals their monoclonal origin.

The derivation of ovarian intestinal-type mucinous tumours is not well established. Some are derived from teratomas but the origin of the majority is not clear. It has been recently proposed that the non-germ cell group may be derived from Brenner tumours, as the association of a mucinous tumour with a Brenner tumour is frequently observed. In order to explore the histogenesis of these neoplasms, we undertook a clonality analysis of the two components of ten combined Brenner and mucinous tumours using a human androgen receptor gene (HUMARA) assay. All eight informative cases of ten showed a concordant X-chromosome inactivation pattern between the two tumour components, indicative of a shared clonal origin (p = 0.0039). Microsatellite genotyping in five of the combined tumours displayed an identical heterozygous pattern with paired Fallopian tube tissue, indicative of a somatic cell origin. In addition, paired box protein 8, a highly sensitive Müllerian epithelial marker, was not detected by immunohistochemistry in either tumour component in any of the ten tumours, suggesting that this subset of mucinous tumours does not originate from Müllerian-derived epithelium. In conclusion, this study demonstrates that in combined mucinous and Brenner tumours, there is a shared clonal relationship between the two different tumour components and suggests that some pure mucinous tumours may develop from a Brenner tumour in which the Brenner tumour component becomes compressed and obliterated by an expanding mucinous neoplasm.

Multicentric occurrence of multiple papillary thyroid carcinomas--HUMARA and BRAF mutation analysis.

Papillary thyroid carcinomas (PTCs) occasionally form multiple tumor foci in different sites of the same thyroid gland. However, it is controversial whether discrete nodules of PTC arise independently (multicentric occurrence) or are seeded from a single tumor via lymphatic channels (intraglandular metastasis). In order to determine the clonal origin of multiple PTCs, we examined X-chromosome inactivation patterns using a human androgen receptor gene-based assay (HUMARA) and the BRAF mutation using allele-specific PCR (AS-PCR) in 32 microdissected cancerous tissues from 14 Japanese women with multifocal PTC. All tumor foci were greater than 3 mm in size and met the criteria for microscopic classical PTC. Samples from 13 of the 14 patients were informative based on HUMARA. Tumor foci from two cases (15.4%) displayed a discordant X-chromosome inactivation pattern. Foci from the other 11 cases (84.6%) showed a concordant inactivation pattern of the X-chromosome. AS-PCR indicated that BRAF mutational status between the tumor foci was discordant in three (25%) and concordant in nine (75%) of 12 available cases. When the results of these two molecular analyses were combined, 28.6% of the cases were discordant in X-chromosome inactivation pattern and/or BRAF mutation, suggesting multicentric origin. Some of the remaining concordant cases also may be of multicentric origin. These results support a hypothesis that multicentric occurrence in multiple PTCs may be common, possibly greater than 30%. Although the exact mechanism of multicentric occurrence is still unclear, our findings contribute to the understanding the histogenesis of papillary thyroid carcinoma.

Distinctive renal cell tumor simulating atrophic kidney with 2 types of microcalcifications. Report of 3 cases.

We report 3 cases of primary renal cell tumor simulating atrophic kidney with distinct gross, morphologic, immunohistochemical, and molecular genetic features. The tumors were retrieved out of more than 17 000 renal tumors from the Plzen Tumor Registry. Tissues for light microscopy had been fixed, embedded, and stained with hematoxylin and eosin using routine procedures. The tumors were further analyzed using immunohistochemistry, array comparative genomic hybridization, and human androgen receptor. Analyses of VHL gene and loss of heterozygosity (LOH) 3p were also performed. The patients were 2 women and 1 man, with ages ranging from 29 to 35 years (mean, 31.3 years). Grossly, the neoplasms were encapsulated and round with largest diameter of 3.5 cm (mean, 3.2 cm). Follow-up available for all patients ranged from 2 to 14 years (mean, 8 years). No aggressive behavior was noted. Histologically, akin to atrophic (postpyelonephritic) kidney parenchyma, the tumors were composed of follicles of varying sizes that were filled by eosinophilic secretion. Rare areas contained collapsed follicles. Each follicle was endowed with a small capillary. The stroma was loose, inconspicuous, and focally fibrotic. Two types of calcifications were noted: typical psammoma bodies and amorphous dark-blue stained calcified deposits. Immunohistochemically, tumors were strongly positive for cytokeratins (OSCAR), CD10, and vimentin, with weak immunopositivity for CAM5.2 and AE1-AE3. WT1 and cathepsin K were weakly to moderately focally to diffusely positive. Tumors were negative for cytokeratin 20, carbonic anhydrase IX, parvalbumin, HMB45, TTF1, TFE3, chromogranin A, thyroglobulin, PAX8, and ALK. Only 1 case was suitable for molecular genetic analyses. No mutations were found in the VHL gene; no methylation of VHL promoter was noted. No numerical aberrations were found by array comparative genomic hybridization analysis. LOH for chromosome 3p was not detected. Analysis of clonality (human androgen receptor) revealed the monoclonal nature of the tumor. We describe an unknown tumor of the kidney that (1) resembles renal atrophic kidney or nodular goiter of thyroidal gland; (2) contains a leiomyomatous capsule and 2 types of calcifications; (3) lacks mitoses, atypias, necroses, and hemorrhages and nearly lack Ki-67 positivity; and (4) so far showed benign biological behavior.

Clonality analysis of giant cell lesions of the jaws

Despite the importance of clonality to understand the pathogenesis and progression of tumors, it has not been investigated yet in giant cell lesions of the jaws. The aim of this study was to analyze the clonality of peripheral giant cell lesions (PGCL) and central giant cell lesions (CGCL) of the jaws. Six samples of PGCL and 5 samples of CGCL were analyzed in this study using the polymorphic human androgen receptor locus (HUMARA) assay. Three out of the 5 samples of the CGCL and 3 out of 6 samples of PGCL exhibited a monoclonal pattern. Our findings demonstrate that some giant cell lesions of the jaws are clonal, which indicate that these lesions may have a common genetic mechanism of development. Further studies are necessary to better elucidate the molecular mechanisms involved in the pathogenesis of such lesions.

Apesar da importância que a clonalidade das lesões tem para o entendimento da patogênese e progressão dos tumores, ainda não foi feita essa investigação em lesões de células gigantes dos maxilares. O objetivo desse trabalho foi analisar a natureza clonal de lesões periféricas de células gigantes (LPCG) e de lesões centrais de células gigantes (LCCG). Foram analisadas nesse estudo 6 amostras de LPCG e 5 amostras de LCCG, sendo todas elas provenientes de pacientes do sexo feminino. Para essa investigação foi utilizado o método baseado na região polimórfica do exon um do gene humano para oreceptor de andrógeno (HUMARA). Três das 5 amostras de LCCG e 3 das 6 amostras de LPCG exibiram um padrão monoclonal. Nossos resultados demonstram que algumas lesões de células gigantes dos maxilares apresentam uma natureza monoclonal indicando que essas lesões podem ter um mecanismo genético comum de desenvolvimento. Outros estudos são necessários para uma maior compreensão dos mecanismos moleculares envolvidos na patogênese dessas lesões.

Cryptic mosaicism involving a second chromosome X in patients with Turner syndrome

The high abortion rate of 45,X embryos indicates that patients with Turner syndrome and 45,X karyotype could be mosaics, in at least one phase of embryo development or cellular lineage, due to the need for the other sex chromosome presence for conceptus to be compatible with life. In cases of structural chromosomal aberrations or hidden mosaicism, conventional cytogenetic techniques can be ineffective and molecular investigation is indicated. Two hundred and fifty patients with Turner syndrome stigmata were studied and 36 who had female genitalia and had been cytogenetically diagnosed as having "pure" 45,X karyotype were selected after 100 metaphases were analyzed in order to exclude mosaicism and the presence of genomic Y-specific sequences (SRY, TSPY, and DAZ) was excluded by PCR. Genomic DNA was extracted from peripheral blood and screened by the human androgen receptor (HUMARA) assay. The HUMARA gene has a polymorphic CAG repeat and, in the presence of a second chromosome with a different HUMARA allele, a second band will be amplified by PCR. Additionally, the CAG repeats contain two methylation-sensitive HpaII enzyme restriction sites, which can be used to verify skewed inactivation. Twenty-five percent (9/36) of the cases showed a cryptic mosaicism involving a second X and approximately 14 percent (5/36), or 55 percent (5/9) of the patients with cryptic mosaicism, also presented skewed inactivation. The laboratory identification of the second X chromosome and its inactivation pattern are important for the clinical management (hormone replacement therapy, and inclusion in an oocyte donation program) and prognostic counseling of patients with Turner syndrome.

Polymorphism and forensic efficiency of 5X-STR loci in Korean / 대한법의학회지

This study intends to examine the polymorphism of 5 STR loci inX-chromosome (GATA172D05, HPRTB, DXS8377, DXS101, HumARA) and to evaluate usefulness of them in forensic identification. 100 unrelated Korean men and women were selected. DNA was extracted from these sample and PCR was performed to amplify it. And using automated DNA sequencer and computer program, the genotype and allele frequency of them were investigated and analyzed. The following results were obtained: 1. The genetic analysis of 5 STR loci inX-chromosome was performed with quadruplex PCR for GATA172D05, HPRTB, DXS8377, HumARA and monoplex PCR for DXS101. 2. Polymorphism information content of 5 loci is higher than 0.5, the high information content is observed. The heterozygosity is higher in DXS8377, DXS101, HumARA than others. 3. The power of discrimination is revealed high in all 5 loci in women, but in men DXS8377 and HumARA is higher than others. 4. The mean exclusion chance is revealed high in DXS8377 and HumARA which have more alleles than others in trio case and motherless case. 5. The difference of allele frequency is observed with other population group in DXS8377, DXS101, HumARA of Korean population group. Based on the results of this study, the allele frequency and population data of 5 STR loci inX-chromosome may be useful in forensic investigation.

Clonal Analysis of Neurofibroma by PCR Amplification of HUMARA Gene

BACKGROUND: While neurofibromas have generally been regarded as polyclonal hyperplastic lesions, it remains unclear whether the tumor is a true neoplasm or a hyperplastic lesion. METHODS: Determination of clonality by X chromosome inactivation pattern was investigated in twenty-one cases of neurofibroma employing enzyme digestion and PCR of the HUMARA gene. The histological, immunohistochemical, and ultrastructural characteristics of the tumors were also examined. RESULTS: Immunohistochemically, most of the tumor cells showed vimentin and S-100 protein positivity. Axons were demonstrated by neurofilament protein positivity and were seen mainly at the periphery and rarely in the central portion of the tumor. Ultrastructurally, the tumors were composed of a variety of cell types: perineurial cells, Schwann cells, fibroblasts, and axons. X chromosome inactivation analysis was completed on thirteen out of fifteen cases in which DNA was successfully extracted. Of thirteen neurofibromas that were heterozygous at the HUMARA loci, eleven showed a polyclonal pattern. The remaining two cases were considered as indeterminate for clonality because of unequal band intensity and failure to obtain the normal control DNA. CONCLUSION: The results from this study suggest that neurofibromas are polyclonal in origin and might be a neoplastic lesion comprising non-neoplastic cells among constituent components.

Study on the application of differentially methylated X-linked HUMARA in forensic medicine / 中国法医学杂志

Objective To study the Application of X-linked differentially methylated polymorphism site in forensic medicine.Methods X-STR HUMARA was chosen as a model locus.PCR procedures were performed after digestion using methylation-sensitive restriction endonucleases.STR polymorphism of HUMARA was analyzed and compared in samples collected from male and female individuals.Result After digestion with methylation-sensitive restriction enzyme HpaⅡ,no PCR products were obtained from male samples,whereas PCR products from the female samples were normally typed.In monoclonal tumor cell samples from females,only one allele was detected.Conclusion The differentially methylated X-STR HUMARA locus is a novel marker for mixture analysis of mixed stains,sex determination and discrimination of tumor tissues.

Clonality Assay of Dysplastic Epithelial Lesions of the Stomach

PURPOSE: Dysplasia or flat adenoma of the stomach is regarded as a precancerous lesion. However, the frequency and the evolutionary process of malignant transformation of gastric dysplasia are still debated. In order to see whether the lesion was a monoclonal or a polyclonal proliferation, clonality was assayed by X-linked HUMARA polymorphism. MATENRIALS AND METHODS: DNA was extracted from the paraffin-embedded tissue of 16 consecutive cases of endoscopic biopsy, eight of which supplied both dysplastic and nondysplastic tissue for comparison. HUMARA was amplified by PCR with or without pretreatment with methylation- sensitive restriction enzyme, HpaII. The amplification products were electrophoresed on polyacrylamide gel and silver-stained. RESULTS: Among the 16 cases, 13 cases were informative and 3 cases noninformative. Of the 13 cases, one case showed skewed lyonization, rendering 12 cases to be analyzed further. A monoclonal band pattern was noted in 2 cases, and a polyclonal band pattern in 10 cases. A review of the histopathologies of the monoclonal and the polyclonal cases did not reveal features discriminating the two groups. CONCLUSION: These results suggest that gastric dysplasia is a disease entity heterogeneous in the genetic level, and many cases may be non-neoplastic.