Down's Syndrome

Mechanisms:  94% non-dysjunction at anaphase I or II 3-4% translocation 2-3% Mosaicism (germline or gonadal)

Typically a spontaneous event, unless caused by a translocation. To calculate recurrence risk must take into account: Maternal age Previous history (more likely if previously had children with T21) Karyotype of previously affected child Parental karyotype

Nuchal Translucency ScanCan be carried out during the dating scan (ultrasound) 11-14 weeksIn combination with a blood test and maternal age can work out whether pregnancy is high riskQuadruple Blood Test14-20 weeks gestation. 82% accuracy. If shown to be high risk on either of these tests can have CVS (11-14 weeks) or amniocentesis (15-20 weeks)

Characteristic appearance - facial, short stature Personality - friendly, no sense of danger LD/DD Hypotonia Higher risk of infections Heart defects Leukaemia Mental Health Problems - Autism Epilepsy Alzheimer's Eye problems - cataracts, eyes don't move together Hearing problems Low thyroid Constipation

Clinical Features

inheritance

Genetics

tests