In addition to 18q-, other syndromes of the disorder include trisomy 18, where there are three copies of the chromosome rather than the usual two; 18p-, where a piece is missing from the " short arm " of the chromosome; Ring 18, in which one of the copies of the chromosome forms a ring; and tetrasomy 18p, where an extra chromosome is present.
22.
Other entities associated with an imperforate anus are trisomies 18 and 21, the cat-eye syndrome ( partial trisomy or tetrasomy of a maternally derived number 22 chromosome ), Baller-Gerold syndrome, Currarino syndrome, caudal regression syndrome, FG syndrome, Johanson-Blizzard syndrome, McKusick-Kaufman syndrome, Pallister-Hall syndrome, short rib-polydactyly syndrome type 1, Townes-Brocks syndrome, 13q deletion syndrome, urorectal septum malformation sequence, and the OEIS complex ( omphalocele, exstrophy of the cloaca, imperforate anus, spinal defects ).
