<unk>  is a chromosomal abnormality, a syndrome in which a patient has an additional chromosome 13 due to a non-disjunction of chromosomes during meiosis.  The extra chromosome 13 disrupts the normal course of development, causing the characteristic features of<unk> .
Patau syndrome
Sotos syndrome
Boyd-Stearns syndrome
Clark-Baraitser syndrome
Mungan syndrome
Fryns syndrome
Leopard syndrome
Pierson syndrome