A deletion involving the long arm of chromosome 18 may be associated with a number of phenotypic findings. In general, the larger the deletion the more severe the disorder. A patient with a small deletion may appear normal.


Clinical features:

(1) postnatal growth retardation and short stature

(2) mental retardation

(3) behavioral problems

(4) hypotonia

(5) poor coordination


Facial features:

(1) midfacial hypoplasia with deep set eyes

(2) ocular abnormalities (retinal defect, optic atrophy, iris hypoplasia, nystagmus, microphthalmia, other)

(3) inner epicanthal folds

(4) slanted palpebral fissures

(5) carp-shaped mouth

(6) cleft palate and/or cleft lip

(7) prominent antihelix and/or antitragus

(8) other ear abnormalities (low set ears, conduction deafness, defect external canal, middle ear defects)


Changes in the extremities:

(1) short legs

(2) foot abnormalities (small, talipes equinovarus, other)

(3) hand abnormalities (high frequency whorl digital pattern, simian crease, fifth finger clinodactyly, long hand, other)


Other findings:

(1) males: hypospadias, cryptorchidism

(2) females: hypoplastic labia minora

(3) urethral reflux with recurrent urinary tract infection

(4) seizures


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