Biomaterial Database

An atypical Turner syndrome patient with ring X chromosome mosaicism. 1995

E S Cantú, and D F Jacobs, and G S Pai

Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston 29425, USA.

Small marker chromosomes (SMC) associated with severe Turner syndrome (TS) variants often represent reduced X chromosomes lacking the X inactivation center (XIC), perturbed dosage compensation, and unbalanced gene expression. A TS patient with mental retardation (MR), unusually short stature, facial and limb malformations, and karyotypic mosaicism involving SMCs is described. Cytogenetic and fluorescence in situ hybridization (FISH) studies of blood and lymphoblastoid cells showed that the SMC was X-chromosome derived, contained a functional centromere, and had ring formation. Karyotypes of 45/46,X,r(X) in blood cells and 45,X/46,-XX/46,X,r(X)/47,X,r(X), + r(X) in fibroblasts were found. Late-replication of the SMC was inconclusive, but the X inactivation specific transcript (XIST) locus within XIC was demonstrated by fluorescent in situ hybridization (FISH). Mechanisms are reviewed that can account for our patient's unusual TS phenotype.

UI	MeSH Term	Description	Entries
D007621	Karyotyping	Mapping of the KARYOTYPE of a cell.	Karyotype Analysis Methods,Analysis Method, Karyotype,Analysis Methods, Karyotype,Karyotype Analysis Method,Karyotypings,Method, Karyotype Analysis,Methods, Karyotype Analysis
D009030	Mosaicism	The occurrence in an individual of two or more cell populations of different chromosomal constitutions, derived from a single ZYGOTE, as opposed to CHIMERISM in which the different cell populations are derived from more than one zygote.
D002478	Cells, Cultured	Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.	Cultured Cells,Cell, Cultured,Cultured Cell
D004303	Dosage Compensation, Genetic	Genetic mechanisms that allow GENES to be expressed at a similar level irrespective of their GENE DOSAGE. This term is usually used in discussing genes that lie on the SEX CHROMOSOMES. Because the sex chromosomes are only partially homologous, there is a different copy number, i.e., dosage, of these genes in males vs. females. In DROSOPHILA, dosage compensation is accomplished by hypertranscription of genes located on the X CHROMOSOME. In mammals, dosage compensation of X chromosome genes is accomplished by random X CHROMOSOME INACTIVATION of one of the two X chromosomes in the female.	Dosage Compensation (Genetics),Gene Dosage Compensation,Hypertranscription, X-Chromosome,X-Chromosome Hypertranscription,Compensation, Dosage (Genetics),Compensation, Gene Dosage,Compensation, Genetic Dosage,Dosage Compensation, Gene,Gene Dosage Compensations,Genetic Dosage Compensation,Genetic Dosage Compensations,Hypertranscription, X Chromosome,X Chromosome Hypertranscription
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D012303	Ring Chromosomes	Aberrant chromosomes with no ends, i.e., circular.	Chromosomes, Ring,Chromosome, Ring,Ring Chromosome
D014424	Turner Syndrome	A syndrome of defective gonadal development in phenotypic females associated with the karyotype 45,X (or 45,XO). Patients generally are of short stature with undifferentiated GONADS (streak gonads), SEXUAL INFANTILISM, HYPOGONADISM, webbing of the neck, cubitus valgus, elevated GONADOTROPINS, decreased ESTRADIOL level in blood, and CONGENITAL HEART DEFECTS. NOONAN SYNDROME (also called Pseudo-Turner Syndrome and Male Turner Syndrome) resembles this disorder; however, it occurs in males and females with a normal karyotype and is inherited as an autosomal dominant.	Bonnevie-Ullrich Syndrome,Gonadal Dysgenesis, 45,X,Gonadal Dysgenesis, XO,Monosomy X,Status Bonnevie-Ullrich,Turner's Syndrome,Ullrich-Turner Syndrome,Bonnevie Ullrich Syndrome,Status Bonnevie Ullrich,Syndrome, Ullrich-Turner,Turners Syndrome,Ullrich Turner Syndrome,XO Gonadal Dysgenesis
D014960	X Chromosome	The female sex chromosome, being the differential sex chromosome carried by half the male gametes and all female gametes in human and other male-heterogametic species.	Chromosome, X,Chromosomes, X,X Chromosomes