Info

iiq-

(Helmuth et al. 1989)149

18r

(Cohen et al. 1972)

18p-

(Nitowkski et al. 1966; Faint and Lewis 1964)

noncolobomatous forms of microphthalmia; Table 3-2 describes the association with synophthalmia/cyclopia.

All forms of microscopically identifiable chromosomal deletions, duplications, or aneuploidies are associated with some element of mental retardation with the exception of some X-chromosomal anomalies. Chromosomal analysis may be appropriate for diagnostic purposes for patients with mental, developmental, or growth retardation and two or more congenital anomalies.

Prenatal diagnosis of chromosomal and some single gene disorders can be performed by either traditional amniocentesis or chorion villus sampling, a technique that can be performed as early as the eighth week after conception. The indications include "advanced" maternal age, a parent being a carrier of a balanced chromosomal rearrangement, a previously affected child or relative, or a fetal anomaly detected by ultrasonography. Although clinically significant structural ocular anomalies such as hypo- or hypertelorism and microphthalmia/anophthalmia have been detected prenatally, they are usually detected in association with other fetal anomalies. Some prenatally determined ocular anomalies, such as congenital cataracts, have rarely been detected before the third or late second trimester.

Mental retardation occurs in most of the genetic syndromes in this chapter so this chapter does not include mental retardation in the description of the chromosomal anomalies unless it is unique or not evident.

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