Earlyonset Cataracts

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Approximately 1/250 infants are born with a cataract (Robinson and Linden, 1993). Worldwide, 10% of all blindness is attributed to congenital cataracts (Rabinowitz et al., 1997). Cataracts seem to be involved in the aging process, for all humans will develop cataracts that can impair vision if they live to an advanced age. The upper age limit that is considered "early" for the onset of cataracts is debatable (R. Kalina, personal communication).

Determining the significance of a family history of cataracts can be sorted by the age of presentation of the cataracts (congenital; infancy, <12 months; childhood, 1-15 years; and adult, >15 years). Approximately 70-75% of congenital cataracts

TABLE 4.8 The Medical-Family History Approach to Visual Loss

• What was the person's age at the onset of blindness or visual loss?

• Document with ophthalmologic records the area of visual pathology (some conditions will overlap in more than one area):

Retina (e.g., retinitis pigmentosa, macular degeneration, retinoblastoma)

Choroid (e.g., choroideremia)

Optic nerve or disc (e.g., atrophy, hypoplasia)

Lens (e.g., cataract, ectopia lentis)

Eyeball or globe (e.g., high myopia, glaucoma, structural defect such as microphthalmos or anophthalmos)

Iris (uvea) and uveal tract (e.g., aniridia or iris hypoplasia, coloboma, chorioretinitis) Nystagmus (common in disorders of hypopigmentation such as albinism)

• Is the visual disturbance bilateral or unilateral? (bilateral disease is more likely to have a genetic etiology)

• Did the mother of the person with visual impairment have any infections during the pregnancy?

• Are the parents of the person with visual impairment related as cousins (or more closely)? (suggestive of autosomal recessive inheritance)

• Does the person (or other family members) have other diseases or medical conditions? Focus on:

Dysmorphic features with or without other birth anomalies (see Section 4.2) Hearing loss (see Section 4.3). The various forms of the autosomal recessive Usher syndrome (retinitis pigmentosa with sensorineural hearing loss) account for 8% of profound deafness in children. Among the deaf-blind population, RP has a prevalence estimated at 50% (Gorlin et al., 1995) Mental retardation or learning disabilities (see Section 4.5) Neurological disease (see Section 4.7) Dementia (see Section 4.9) Pigmentary and skin abnormalities Short stature (see Section 4.14) Diabetes (see Section 4.15)

Reproductive anomalies including hypogonadism (see Section 4.16)

Source: Arnould and Hussels, 1997; Gorlin et al., 1995.

are nongenetic in etiology. Worldwide, maternal infections (e.g., rubella, varicella, toxoplasmosis) are an important cause of congenital cataracts. Diabetes mellitus is a frequent fundamental metabolic factor in the development of childhood cataracts. Presenile cataracts can be secondary to an underlying lens anomaly, which may or may not have a hereditary etiology (Rabinowitz et al., 1997) such as:

1. Ectopia lentis (dislocated lens). Ectopia lentis can occur as a result of a traumatic blow to the head, as an isolated hereditary condition (autosomal dominant or recessive), or as a feature of an inherited syndrome (such as Marfan syndrome or homocystinuria).

2. Iris coloboma (notching). Iris colobomas are associated with several chromosomal anomalies and CHARGE association. Colobomas may occur after an injury or surgery.

3. Multiple lenticonus (a bulge in the front or back of the lens).

4. Retinal degeneration associated with retinitis pigmentosa (usually develops after the age of 30 years).

Several chromosomal syndromes are associated with the development of cataracts at a young age (Rabinowitz et al., 1997). Early age at onset of cataracts is seen in several inborn errors of metabolism (see Table 4.9) in which the underlying defect is in cholesterol synthesis or metabolism (e.g., galactosemia, manosidosis, neuraminidase deficiency, Lowe syndrome, Wilson disease, untreated PKU, Smith-Lemli-Opitz syndrome, Zellweger syndrome, cerebrotendinous xanthomatosis, mevalonic aciduria) (Berry and Bennett, 1998; Rabinowitz et al., 1997).

TABLE 4.9 Examples of Hereditary and Environmental Syndromes Associated with Early-Onset Cataracts

Age at

Presentation Syndrome

Inheritance Patterna

Other Cardinal Featuresa

Birth

Lowe (oculocerebrorenal) XL syndrome

Zellweger syndrome AR

Rhizomelic chondrodysplasia AR

punctata Cockayne syndrome B AR

Warburg syndrome

Marshall syndrome

Oculomandibulofacial ?

syndrome (Hallerman-Streiff)

Newborn Galactosemia (1 wk-1 mo)

Fetal rubella

Maternal infection

Short stature, sebaceous cysts, MR, hypotonia, dysmorphic features, renal disease Seizures, dysmorphic features, joint contractures, hepatomegaly, hypotonia MR, proximal limb shortening, ichthyosis LD/MR (progressive), dysmorphic features, hearing loss, retinal degeneration, premature aging, short stature MR, severe brain malformations, other eye anomalies, congenital muscular dystrophy Hearing loss, dysmorphic features, skeletal anomalies, ectodermal dysplasia Dysmorphic features including characteristic beaked nose, variable LD/MR, dental anomalies, dermatologic findings Successful dietary intervention with lactose-free diet but may still have LD, growth delays, ovarian failure; identified by newborn screening in the United States

MR, deafness, chorioretinitis, glaucoma, patent ductus arteriosis, peripheral pulmonic stenosis, myocardial disease

(continued)

TABLE 4.9 (continued)

Age at

Inheritance

Presentation

Syndrome

Patterna

Other Cardinal Featuresa

Fetal varicella

Maternal infection

MR, seizures, chorioretinitis, limb/digit anomalies, growth deficiency

Infancy

Galactokinase deficiency

AR

Cataracts may be only

(1-12 mo)

manifestation

Lysosomal storage diseases

AR, XL

Coarsening facies, MR/LD, hepatosplenomegaly, bony changes (dysostosis multiplex)

Smith-Lemli-Opitz syndrome

AR

MR, short stature, dysmorphic features, genitourinary and limb anomalies

Childhood

Wilson disease

AR

Liver disease from copper

(1-5 y)

accumulation, psychiatric disease, neurological deterioration

Neurofibromatosis II

AD

Hearing loss, vestibular schwannomas, brain tumors (meningomas, gliomas)

Stickler syndrome

AD

LD, dysmorphic features, retinal detachment, myopia, hypotonia, hyperextensible joints, skeletal anomalies, cleft palate

Incontinentia pigmenti

XL (lethal in males)

MR/LD, neurological deficits, skin lesions which are replaced by hyper-pigmented/hypopigmented areas, dental anomalies

Pseudohypoparathyroidism

XL

LD, short stature, brachydactyly, hypocalcemia

Adulthood

Myotonic muscular dystrophy

AD

Myotonia, muscle weakness,

(>15 y)

ptosis

Cerebrotendinous

AR

Xanthomas, thickening

xanthomatosis

tendons, spasticity, dysarthria, dementia and neurological deterioration, cardiovascular disease

Alport syndrome

AD, XL

Sensorineural hearing loss, renal disease

Werner syndrome

AR

Characteristic dermatologic pathology and facies, short stature, hypogonadism, premature aging

"Abbreviations: LD = learning disabled; MR = mental retardation; AD = autosomal dominant; AR = autosomal recessive; XL = X-linked; ? = unknown etiology.

Sources: Clarke, 1996; Jones, 1997; Rabinowitz et al., 1997; Saudubray and Charpentier, 1995; Sybert, 1997.

"Abbreviations: LD = learning disabled; MR = mental retardation; AD = autosomal dominant; AR = autosomal recessive; XL = X-linked; ? = unknown etiology.

Sources: Clarke, 1996; Jones, 1997; Rabinowitz et al., 1997; Saudubray and Charpentier, 1995; Sybert, 1997.

TABLE 4.10 Medical-Family History Queries for Cataracts

• At what age were the cataracts diagnosed?

• Are the cataracts in both eyes?

• Does the person have other problems with his or her eyes? (obtain ophthalmologic records)

• Does the person with the cataracts have a history of diabetes?

• Does the person have any unusual facial or physical features?

• What is the height of the person?

• Is the person unusually tall or short compared to other family members? (record parental and sibling heights)

• Did the mother of the person with cataracts have any infections in pregnancy?

• Does the person with cataracts, or his or her family members, have:

Other medical problems? Explain

Any unusual skin findings? Describe

Mental retardation or learning disabilities? (see Section 4.5)

Hearing loss? (note severity and age at onset, see Section 4.3)

Heart disease? (see section 4.11)

Any muscle weakness?

Any neurological problems (such as slurred speech, unsteady gait, seizures)? (see Section 4.7)

• Psychiatric disease, dementia, or significant behavioral problems? (see Section 4.10)

Any kidney disease? (see Section 4.13)

• Do other people in the family have cataracts or other eye diseases?

Because multiple rare syndromes feature early-onset cataracts (see Table 4.9), referral to a medical geneticist is recommended. Table 4.10 reviews the family-medical history questions for cataracts.

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