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Fulltext Female chromosome X mosaicism is age-related and preferentially affects the inactivated X chromosome

Machiela MJ, Zhou W, Karlins E, Sampson JN, Freedman ND, Yang Q, et al.

Nat Commun, 2016 06 13;7:11843.
PMID: 27291797 DOI: 10.1038/ncomms11843

To investigate large structural clonal mosaicism of chromosome X, we analysed the SNP microarray intensity data of 38,303 women from cancer genome-wide association studies (20,878 cases and 17,425 controls) and detected 124 mosaic X events >2 Mb in 97 (0.25%) women. Here we show rates for X-chromosome mosaicism are four times higher than mean autosomal rates; X mosaic events more often include the entire chromosome and participants with X events more likely harbour autosomal mosaic events. X mosaicism frequency increases with age (0.11% in 50-year olds; 0.45% in 75-year olds), as reported for Y and autosomes. Methylation array analyses of 33 women with X mosaicism indicate events preferentially involve the inactive X chromosome. Our results provide further evidence that the sex chromosomes undergo mosaic events more frequently than autosomes, which could have implications for understanding the underlying mechanisms of mosaic events and their possible contribution to risk for chronic diseases.

Matched MeSH terms: Chromosomes, Human, X/genetics*
Fulltext A rare case of ambiguous genitalia

Ng SF, Boo NY, Wu LL, Shuib S

Singapore Med J, 2007 Sep;48(9):858-61.
PMID: 17728969

Genes on the Y chromosome are essential for normal sex determination and sex differentiation of male genitalia. However, genes on the X chromosome and other autosomes have been shown to be anti-testes and have a detrimental effect on this process. Addition of X chromosomes to the 46,XY karyotype results in seminiferous tubules dysgenesis, hypogonadism and malformed genitalia. We report a term male newborn with 49,XXXXY syndrome presenting with ambiguous genitalia, multiple extra-gonadal anomalies, facial dysmorphism, and radioulnar synostosis.

Matched MeSH terms: Chromosomes, Human, X/genetics*
Amelogenesis imperfecta: enamel ultra structure and molecular studies

Gopinath VK, Al-Salihi KA, Yean CY, Ann MC, Ravichandran M

J Clin Pediatr Dent, 2004;28(4):319-22.
PMID: 15366620

Amelogenesis imperfecta (AI) is a hereditary disorder resulting in generalized defects in the enamel. The case reported here is of a seven-year-old male child with yellow color of all his teeth. Two of his primary molars were extracted due to dental abscess with advanced root resorption. Histologically hypoplastic enamel layer, positively birefringent, generalized pitting, roughness with irregular general cracked borders were observed. Scanning electron microscope, revealed extensive irregular, disorganized rough superficial enamel layer. The enamel was irregularly decussate with filamentous prisms accompanied by small rounded formations. The morphological and histological examination of the tooth revealed that this patient has the features of AI. For genetic study blood sample were collected from the patient and PCR analysis revealed that there is no mutation in exons 1-7 of AMELX gene on the X chromosome of the patient. Hence, it is probable that the AI of this patient is not X-linked. It is more likely to be an autosomal mutation.

Matched MeSH terms: Chromosomes, Human, X/genetics
A mother with variant Turner syndrome and two daughters with trisomy X: a case report

Ramachandram S, Keng WT, Ariffin R, Ganesan V

J Genet, 2013;92(2):313-6.
PMID: 23970090
Matched MeSH terms: Chromosomes, Human, X/genetics
Fulltext Identification of Potential Genes for Benign Prostatic Hyperplasia and Prostate Cancer Susceptibility in Four X-chromosome Regions with High Frequency of Microvariant Alleles

Albujja MH, Messaudi SA, Vasudevan R, Al Ghamdi S, Chong PP, Ghani KA, et al.

Asian Pac J Cancer Prev, 2020 08 01;21(8):2271-2280.
PMID: 32856855 DOI: 10.31557/APJCP.2020.21.8.2271

BACKGROUND: The X-chromosome has been suggested to play a role in prostate cancer (PrCa) since epidemiological studies have provided evidence for an X-linked mode of inheritance for PrCa based on the higher relative risk among men who report an affected brother(s) as compared to those reporting an affected father. The aim of this study was to examine the potential association between the forensic STR markers located at four regions Xp22.31, Xq11.2-12, Xq26.2, and Xq28 and the risk of BPH and PrCa to confirm the impact of ChrX in the PrCa incidence. This may be helpful in the incorporation of STRs genetic variation in the early detection of men population at risk of developing PrCa.
METHODS: DNA samples from 92 patients and 156 healthy controls collected from two medical centers in Riyadh, Saudi Arabia were analyzed for four regions located at X-chromosome using the Investigator® Argus X-12 QS Kit.
RESULTS: The results demonstrated that microvariant alleles of (DXS7132, DXS10146, HPRTB, DXS10134, and DXS10135) are overrepresented in the BPH group (p < 0.00001). Allele 28 of DXS10135 and allele 15 of DXS7423 could have a protective effect, OR 0.229 (95%CI, 0.066-0.79); and OR 0.439 (95%CI, 0.208-0.925). On the other hand, patients carrying allele 23 of DXS10079 and allele 26 of DXS10148 presented an increased risk to PrCa OR 4.714 (95%CI, 3.604-6.166).
CONCLUSION: The results are in concordance with the involvement of the X chromosome in PrCa and BPH development. STR allele studies may add further information from the definition of a genetic profile of PrCa resistance or susceptibility. As TBL1, AR, LDOC1, and RPL10 genes are located at regions Xp22.31, Xq11.2-12, Xq26.2, and Xq28, respectively, these genes could play an essential role in PrCa or BPH.

Matched MeSH terms: Chromosomes, Human, X/genetics*
Fulltext Turner syndrome in diverse populations

Kruszka P, Addissie YA, Tekendo-Ngongang C, Jones KL, Savage SK, Gupta N, et al.

Am J Med Genet A, 2020 Feb;182(2):303-313.
PMID: 31854143 DOI: 10.1002/ajmg.a.61461

Turner syndrome (TS) is a common multiple congenital anomaly syndrome resulting from complete or partial absence of the second X chromosome. In this study, we explore the phenotype of TS in diverse populations using clinical examination and facial analysis technology. Clinical data from 78 individuals and images from 108 individuals with TS from 19 different countries were analyzed. Individuals were grouped into categories of African descent (African), Asian, Latin American, Caucasian (European descent), and Middle Eastern. The most common phenotype features across all population groups were short stature (86%), cubitus valgus (76%), and low posterior hairline 70%. Two facial analysis technology experiments were conducted: TS versus general population and TS versus Noonan syndrome. Across all ethnicities, facial analysis was accurate in diagnosing TS from frontal facial images as measured by the area under the curve (AUC). An AUC of 0.903 (p < .001) was found for TS versus general population controls and 0.925 (p < .001) for TS versus individuals with Noonan syndrome. In summary, we present consistent clinical findings from global populations with TS and additionally demonstrate that facial analysis technology can accurately distinguish TS from the general population and Noonan syndrome.

Matched MeSH terms: Chromosomes, Human, X/genetics