Complete absence or deletion of chromosome 22 causes pre- and postnatal growth retardation, microcephaly, hypotonia, and seizures. Additional features include a flat nasal bridge, bifid uvula, and large, low-set ears. Cardiac anomalies may be evident. Deletions including the pericentric region may result in the DiGeorge anomalad with absent or hypoplastic thymus, absent or hypoplastic parathyroids, and great and conotruncal cardiac malformations; skeletal and limb deformities may also be evident. Ophthalmic features include epicanthus, hyper-telorism, upward slanting of the palpebral fissures, and blepharoptosis.71,175,376
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