Frequency of somatic MEN1 gene mutations in monoclonal parathyroid tumours of patients with primary hyperparathyroidism

OBJECTIVES: Investigation of small numbers of parathyroid tumours by X-chromosome inactivation analysis suggests that the majority of them are monoclonal lesions most likely caused by a somatic mutation. Somatic mutations in the MEN1 gene located on chromosome 11q13 have recently been identified in 12-17% of solitary parathyroid tumours in patients with sporadic primary hyperparathyroidism, and they may be the precipitating genetic defect leading to monoclonal cell proliferation in these tumours. DESIGN: To determine the prevalence of MEN1 gene mutations in monoclonal parathyroid neoplasias we investigated 33 parathyroid tumours of patients with primary hyperparathyroidism for clonality and mutations in the MEN1 gene. METHODS: X-chromosome inactivation analysis was used to assess the clonal status of the tumours, direct sequencing of the complete coding region was applied to identify mutations in the MEN1 gene. RESULTS: Twenty-eight female patients (26 patients with solitary adenoma, 2 patients with hyperplasia) were informative for the polymorphism of the androgen receptor on the X-chromosome and could be tested for inactivation pattern. Nineteen of twenty-six (73%) solitary adenomas were monoclonal. Somatic mutations in the MEN1 gene were identified in nine cases. Six of them were found in the relatively large second exon of the MEN1 gene (A49D, 193del36, 402delC, 482del22, 547delT, W126X). One was found in exon 5 (904del9), one in exon 7 (Y327X) and one in exon 9 (R415X). Of the monoclonal tumours, 5 out of 19 (26%) harboured a somatic MEN1 gene mutation. CONCLUSIONS: In summary, 73% of the solitary parathyroid adenomas were monoclonal. In 26% of the monoclonal tumours a somatic MEN1 gene mutation has been identified. However, for 74% of monoclonal tumours of the parathyroids the underlying genetic defects are still not known.

Download Full-text

Influence of MECP2 Gene Mutation and X-Chromosome Inactivation on the Rett Syndrome Phenotype

Journal of Child Neurology ◽

10.1177/08830738040190070501 ◽

2004 ◽

Vol 19 (7) ◽

pp. 503-508 ◽

Cited By ~ 14

Author(s):

Jong Hee Chae ◽

Hee Hwang ◽

Yong Seung Hwang ◽

Hee Jung Cheong ◽

Ki Joong Kim

Keyword(s):

Gene Mutation ◽

Rett Syndrome ◽

X Chromosome ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Mecp2 Gene

Download Full-text

Molecular Mechanisms of Skewed X-Chromosome Inactivation in Female Hemophilia Patients—Lessons from Wide Genome Analyses

International Journal of Molecular Sciences ◽

10.3390/ijms22169074 ◽

2021 ◽

Vol 22 (16) ◽

pp. 9074

Author(s):

Rima Dardik ◽

Einat Avishai ◽

Shadan Lalezari ◽

Assaf A. Barg ◽

Sarina Levy-Mendelovich ◽

...

Keyword(s):

X Chromosome ◽

Molecular Mechanisms ◽

Gene Mutations ◽

Bioinformatic Analysis ◽

Pathogenic Mutation ◽

X Chromosome Inactivation ◽

Cag Repeat ◽

Chromosome Inactivation ◽

Pcr Analysis ◽

Two Generations

Introduction: Hemophilia A (HA) is an X-linked bleeding disorder caused by factor VIII (FVIII) deficiency or dysfunction due to F8 gene mutations. HA carriers are usually asymptomatic because their FVIII levels correspond to approximately half of the concentration found in healthy individuals. However, in rare cases, a carrier may exhibit symptoms of moderate to severe HA primarily due to skewed inactivation of her non-hemophilic X chromosome. Aim: The aim of the study was to investigate X-chromosome inactivation (XCI) patterns in HA carriers, with special emphasis on three karyotypically normal HA carriers presenting with moderate to severe HA phenotype due to skewed XCI, in an attempt to elucidate the molecular mechanism underlying skewed XCI in these symptomatic HA carriers. The study was based on the hypothesis that the presence of a pathogenic mutation on the non-hemophilic X chromosome is the cause of extreme inactivation of that X chromosome. Methods: XCI patterns were studied by PCR analysis of the CAG repeat region in the HUMARA gene. HA carriers that demonstrated skewed XCI were further studied by whole-exome sequencing (WES) followed by X chromosome-targeted bioinformatic analysis. Results: All three HA carriers presenting with the moderate to severe HA phenotype due to skewed XCI were found to carry pathogenic mutations on their non-hemophilic X chromosomes. Patient 1 was diagnosed with a frameshift mutation in the PGK1 gene that was associated with familial XCI skewing in three generations. Patient 2 was diagnosed with a missense mutation in the SYTL4 gene that was associated with familial XCI skewing in two generations. Patient 3 was diagnosed with a nonsense mutation in the NKAP gene that was associated with familial XCI skewing in two generations. Conclusion: Our results indicate that the main reason for skewed XCI in our female HA patients was negative selection against cells with a disadvantage caused by an additional deleterious mutation on the silenced X chromosome, thus complicating the phenotype of a monogenic X-linked disease. Based on our study, we are currently offering the X inactivation test to symptomatic hemophilia carriers and plan to expand this approach to symptomatic carriers of other X-linked diseases, which can be further used in pregnancy planning.

Download Full-text

X chromosome inactivation pattern in BRCA gene mutation carriers

European Journal of Cancer ◽

10.1016/j.ejca.2012.10.013 ◽

2013 ◽

Vol 49 (5) ◽

pp. 1136-1141 ◽

Cited By ~ 7

Author(s):

Siranoush Manoukian ◽

Paolo Verderio ◽

Silvia Tabano ◽

Patrizia Colapietro ◽

Sara Pizzamiglio ◽

...

Keyword(s):

Gene Mutation ◽

X Chromosome ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Brca Gene ◽

Mutation Carriers ◽

Inactivation Pattern ◽

Brca Gene Mutation

Download Full-text

Clonal Origin of Toxic Thyroid Nodules with Constitutively Activating Thyrotropin Receptor Mutations1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.83.1.4477 ◽

1998 ◽

Vol 83 (1) ◽

pp. 130-134

Author(s):

Knut Krohn ◽

Dagmar Führer ◽

Hans-Peter Holzapfel ◽

Ralf Paschke

Keyword(s):

Somatic Mutation ◽

X Chromosome ◽

Somatic Mutations ◽

Receptor Gene ◽

Clonal Expansion ◽

X Chromosome Inactivation ◽

X Inactivation ◽

Chromosome Inactivation ◽

Tsh Receptor ◽

Clonal Origin

Constitutively activating TSH receptor mutations have recently been detected in toxic nodules. In vitro studies suggest that mutated receptor signaling constitutively elevates cAMP, which causes hyperfunction and proliferation of thyrocytes. Therefore, toxic nodules with constitutively activating somatic TSH receptor mutations should result from clonal expansion of a single mutated cell. To test this hypothesis, we studied the clonal origin of 27 toxic nodules. In 13 of 27 nodules, a somatic mutation in the TSH receptor was identified. A PCR-based clonality assay that analyzes X-chromosome inactivation was used. The assay amplifies a polymorphism located in the androgen receptor gene. Of 27 toxic nodules studied, 23 (85%) were informative for the polymorphism. In the group that contains a somatic mutation in the TSH receptor, 10 of 11 cases showed nonrandom X inactivation, indicating clonal expansion. In only one toxic nodule with a TSH receptor mutation was random X inactivation detected. In the group without detectable mutations in exons 9 and 10 of the TSH receptor and exons 7–10 of the Gsα protein, only 6 of 12 toxic nodules show nonrandom X-chromosome inactivation. Therefore, the majority of toxic nodules with constitutively activating TSH receptor mutations are of clonal origin. This finding supports the hypothesis that toxic nodules arise from aberrant growth of a single cell. It is widely accepted that somatic mutations might initiate monoclonal growth. The TSH receptor mutations in these toxic nodules together with Gsα mutations in others are the most likely candidates for the initiation of this thyroid tumor. The clonal origin of toxic nodules in the group without detected mutations in the TSH receptor or the Gsα protein suggests somatic mutations in genes that are unknown to date.

Download Full-text

X-linked CNV and skewed X-chromosome inactivation

Nauchno-prakticheskii zhurnal «Medicinskaia genetika» ◽

10.25557/2073-7998.2020.03.19-21 ◽

2020 ◽

pp. 19-21

Author(s):

Е.А. Фонова ◽

Е.Н. Толмачева ◽

А.А. Кашеварова ◽

М.Е. Лопаткина ◽

К.А. Павлова ◽

...

Keyword(s):

Cell Proliferation ◽

Intellectual Disability ◽

X Chromosome ◽

Copy Number ◽

Copy Number Variations ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Chromosome X ◽

Skewed X Chromosome Inactivation

Смещение инактивации Х-хромосомы может быть следствием и маркером нарушения клеточной пролиферации при вариациях числа копий ДНК на Х-хромосоме. Х-сцепленные CNV выявляются как у женщин с невынашиванием беременности и смещением инактивации Х-хромосомы (с частотой 33,3%), так и у пациентов с умственной отсталостью и смещением инактивацией у их матерей (с частотой 40%). A skewed X-chromosome inactivation can be a consequence and a marker of impaired cell proliferation in the presence of copy number variations (CNV) on the X chromosome. X-linked CNVs are detected in women with miscarriages and a skewed X-chromosome inactivation (with a frequency of 33.3%), as well as in patients with intellectual disability and skewed X-chromosome inactivation in their mothers (with a frequency of 40%).

Download Full-text

Faculty of 1000 evaluation for Cellular resolution maps of x chromosome inactivation: implications for neural development, function, and disease.

F1000 - Post-publication peer review of the biomedical literature ◽

10.3410/f.718235579.793490044 ◽

2014 ◽

Author(s):

Franck Polleux ◽

Julien Courchet

Keyword(s):

X Chromosome ◽

Neural Development ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Cellular Resolution

Download Full-text

X-Linked Emery–Dreifuss Muscular Dystrophy: Study Of X-Chromosome Inactivation and Its Relation with Clinical Phenotypes in Female Carriers

Genes ◽

10.3390/genes10110919 ◽

2019 ◽

Vol 10 (11) ◽

pp. 919 ◽

Cited By ~ 1

Author(s):

Viggiano ◽

Madej-Pilarczyk ◽

Carboni ◽

Picillo ◽

Ergoli ◽

...

Keyword(s):

Muscular Dystrophy ◽

X Chromosome ◽

Clinical Symptoms ◽

Fibrous Tissue ◽

X Chromosome Inactivation ◽

Chromosome Inactivation ◽

Cardiac Conduction ◽

Asymptomatic Carriers ◽

Cardiac Symptoms ◽

Female Carriers

X-linked Emery–Dreifuss muscular dystrophy (EDMD1) affects approximately 1:100,000 male births. Female carriers are usually asymptomatic but, in some cases, they may present clinical symptoms after age 50 at cardiac level, especially in the form of conduction tissue anomalies. The aim of this study was to evaluate the relation between heart involvement in symptomatic EDMD1 carriers and the X-chromosome inactivation (XCI) pattern. The XCI pattern was determined on the lymphocytes of 30 symptomatic and asymptomatic EDMD1 female carriers—25 familial and 5 sporadic cases—seeking genetic advice using the androgen receptor (AR) methylation-based assay. Carriers were subdivided according to whether they were above or below 50 years of age. A variance analysis was performed to compare the XCI pattern between symptomatic and asymptomatic carriers. The results show that 20% of EDMD1 carriers had cardiac symptoms, and that 50% of these were ≥50 years of age. The XCI pattern was similar in both symptomatic and asymptomatic carriers. Conclusions: Arrhythmias in EDMD1 carriers poorly correlate on lymphocytes to a skewed XCI, probably due to (a) the different embryological origin of cardiac conduction tissue compared to lymphocytes or (b) the preferential loss of atrial cells replaced by fibrous tissue.

Download Full-text