Syndromes due to aneuploidy of gonosomes

Aneuploidy = loss (monosomy) or presence of 1 or more chromosomes in the genome of a cell.

Causes: division disorder ( nondisjunction ) of homologous chromosomes in the I. maturation division or chromatids in the II. I see division.

Overview of syndromes[edit | edit source]

For more information see Turner syndrome.

Karyotype 45,X ;
incidence of about 1/10,000 girls born;
diagnosis: already in the prenatal period ultrasound diagnosis is possible - the fetus is affected by extensive lymphedema mainly in the neck area, after their resorption the skin folds remain permanently visible - pterygia coli ;
signs: small height (100%) – up to 150 cm, wide chest (53%), low hairline on the neck, hypoplasia of nails (60%), pigmented nevi (63%), delayed sexual development, ovaries normally established, gradually however, it turns into fibrous bands , mostly sterility , absence of secondary sexual characteristics (genital dysgenesis – 100%), puberty disorder;
exceptionally congenital defects of internal organs;
frequent mosaics (46,XX/45,X; 45,X/46,XX/47,XXX).

More detailed information can be found on the XXX Syndrome page .

Karyotype 47,XXX ;
incidence of about 1/1,000 girls born;
signs: no typical phenotypic manifestations , non-constant psychomotor retardation, irregular puberty, more frequent spontaneous abortions, limited fertility;
there is no increased incidence of congenital malformations above the population risk.

For more information see Klinefelter syndrome.

Karyotype 47,XXY (other variants are also possible, e.g. 48,XXXY);
incidence of about 1/1,000 male births;
signs: affected boys usually without problems until adolescence, infertility (100%), eunuchoid features, small rigid testes, azoospermia , in all forms hypogenitalism (reduced genitals, 100%), gynecomastia (50%), male psychosexual orientation;
average intelligence, tall stature;
patients with three or more X chromosomes have more often associated congenital developmental defects of internal organs and more severe mental retardation.

For more information see XYY syndrome.

Karyotype 47,XYY ;
incidence of about 1/1,000 male births;
signs: body height over 180 cm , previously considered increased aggressiveness was not confirmed, sometimes mild mental retardation, slightly limited fertility.

ŠTEFÁNEK, Jiří. Medicína, nemoci, studium na 1. LF UK [online]. [cit. 11. 2. 2010]. <http://www.stefajir.cz>.