Down's<unk>  (DS) is caused due to the presence of an extra 21st chromosome (triplication of chromosome 21). 95 percent of DS cases are due to meiotic non-disjunction during meiosis I. 4 percent of DS cases arise due to Robertsonian translocation and very rarely DS may be caused a post-fertilization mitotic error (mosaicism).
Down syndrome causes
Renal agenesis causes
Noonan syndrome causes
Tuberous sclerosis causes
Cystic fibrosis causes
Duodenal atresia causes
Omphalitis causes
Horseshoe kidney causes