Chromosome Location: 22q11
Genetic changes associated with the phenotype:
(1) quadruplicte copies of the affected segment with formation of an extra (supernumary) chromosome (22pter-q11 formed from the inverted duplication of the proximal 22q11 region)
(2) triplicate copies from interstitial duplication without the extra chromosome
Clinical findings may include:
(1) ocular colobomata
(2) anal stensosis atresia
(3) pre-auricular skin tags or pits
(4) downward slanting of the palpebral fissures
(5) variable intelligence (from normal to mild mental retardation)
(6) mild hypertelorism
(7) variable micrognathia
(8) variable congenital heart disease (total anomalous pulmonary venous return, others)
(9) variable genitourinary anomalies (hypospadias, renal agenesis, vesiculourethral reflux, etc)
(10) variable microphthalmia
(11) variable cleft palate
Few patients show all of the "classic" findings so a high index of suspicion is required to make the diagnosis.
FISH and other molecular methods are essential for making the correct diagnosis. Staining with FISH can quickly demonstrate the number of extra copies present.
