Childhood Cataract

Infantile cataract is a significant cause of childhood blindness. The prevalence of congenital cataract is reported between 1 and 3 per 10,000 children. Early detection and prompt treatment are necessary to avoid severe visual loss. Depending on the severity of the cataract, treatment may include pharmacologic pupil dilatation, occlusion therapy, correction of refractive errors, and/or cataract surgery. Visual rehabilitation is required after the cataract surgery in young children. Recognizing the genetic etiology of a childhood cataract may be facilitated by careful attention to the cataract morphology such as anterior lenticonus in Alport syndrome, anterior pyramidal cataract in PAX6 mutations, embryonal or fetal nuclear, cerulean, Coppock cataract, sutural, posterior subcapsular, and others. A unilateral cataract due to persistent fetal vasculature (PFV) is usually not due to a known germline genetic cause. Excellent reviews have been published on the systemic associations with cataract, which may also guide the genetic evaluation. One must also consider the nongenetic causes of cataract including intrauterine infection, trauma, steroids, uveitis, and radiation.


10.2 Molecular Genetics


Approximately 50% of congenital cataract cases have genetic causes. Autosomal dominant (AD), autosomal recessive (AR), and X-linked inheritance patterns have been described, with AD being the most frequent. Mutations in transcription factor genes, developmental genes, genes required in lens development, and lens crystallin genes can cause cataract. ▶ Table 10.1 illustrates examples from these categories. To date, for nonsyndromic cataract, at least 45 loci have been mapped and 38 genes identified.






















































































































































































































































































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Apr 7, 2019 | Posted by in OPHTHALMOLOGY | Comments Off on Childhood Cataract

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Table 10.1 Summary of genes/loci associated with isolated cataract

Cataract description and morphology

Phenotype name (MIM number)

Gene/locus (MIM number)

Chromosome

Inheritance

Other association

Volkmann type (progressive, central, or zonular, with opacities in the embryonic, fetal, and juvenile nucleus and around the anterior and posterior Y-suture)

Cataract 8, multiple types; CTRCT8 (115665)

CTRCT8 (–)

1pter-p36.13

AD


Posterior polar, congenital total, complete, age-related cortical

Cataract 6, multiple types; CTRCT6 (116600)

EPHA2D (176946)

1p36.13

AD

Myopia


Membranous and posterior capsular

Cataract 34, multiple types; CTRCT34 (612968)

CTRCT34 (–)

1p34.3-p32.2

AR

Corneal opacity, microcornea


Congenital, zonular pulverulent, nuclear, nuclear pulverulent, stellate nuclear, nuclear total, total, and posterior subcapsular

Cataract 1, multiple types; CTRCT1 (116200)

CX50, GJA8G (600897)

1q21.2

AD

Cataract-microcornea syndrome


Crystalline coralliform (multiple coral-like white opacities)

Cataract 29; CTRCT29 (115800)

CTRCT29 (–)

2pter-p24

AD


Aculeiform, crystalline aculeiform, crystalline, crystal, frosted, needle-shaped, fasciculiform, congenital cerulean, nonnuclear polymorphic congenital, central nuclear, lamellar, and punctate

Cataract 4, multiple types; CTRCT4 (115700)

CRYGDC (123690)

2q33.3

AD


Coppock-like; embryonic, fetal, infantile nuclear; zonular pulverulent; and lamellar

Cataract 2, multiple types; CTRCT2 (604307)

GRYGC (123680)

2q33.3

AD

Microcornea


Congenital lamellar, anterior polar, and complete

Cataract 39, multiple types; CTRCT39 (615188)

CRYGBC (123670)

2q33.3

AD


Multifocal congenital

Cataract 42; CTRCT42 (115900)

CRYBA2C (600836)

2q35

AD

Eccentric pupil, myopia


Congenital and congenital nuclear

Cataract 18; CTRCT 18 (610019)

FYCO1G (607182)

3p21.31

AR


Congenital nuclear, sutural, stellate cortical; Juvenile-onset lamellar, cortical, nuclear embryonic, or Y-sutural; and adult-onset punctate cortical

Cataract 12, multiple types; CTRCT12 (611597)

BFSP2G (603212)

3q22.1

AD


Progressive polymorphic anterior, posterior, or peripheral cortical, membranous

Cataract 20, multiple types; CTRCT20 (116100)

CRYGSC (123730)

3q27.3

AD


Congenital nuclear

Cataract 41 (116400)

WFS1G (606201)

4p16.1

AD


Congenital, total

Cataract 13 with adult i phenotype (116700)

GCNT2G (600429)

6p24.3-p24.2

AD

i-negative and i-positive red blood type


Cortical, age related

Cataract 28, age related, cortical, susceptibility to; CTRCT28 (609026)

ARCC1G (–)

6p12-q12

–


Congenital

Cataract 38; CTRCT38 (614691)

AGKG (610345)

7q34

AR

Sengers syndrome


Cortical, pulverulent, nuclear, and posterior subcapsular

Cataract 26, multiple types; CTRCT26 (605749)

CAAR (–)

9q13-q22

AR


Congenital, or juvenile cataract

Cataract 36; CTRCT36 (613887)

TDRD7D (611258)

9q22.33

AR


Pulverulent, nuclear

Cataract 30, pulverulent; CTRCT30 (116300)

VIMG (193060)

10p13

AD


Congenital total and posterior polar

Cataract 11, multiple types; cataract 11, syndromic; CTRCT11 (610623)

PITX3T (602669)

10q24.32

AD

Microphthalmia, neurodevelopmental abnormalities


Congenital posterior polar, congenital lamellar, nuclear, complete, and juvenile

Cataract 16, multiple types; CTRCT16 (613763)

CRYABC (123590)

11q23.1

AR, AD

Myofibrillar myopathy, dilated cardiomyopathy


Polymorphic, progressive punctate lamellar, cortical, anterior and posterior polar, nonprogressive lamellar with sutural opacities, embryonic nuclear, and pulverulent cortical

Cataract 15, multiple types; CTRCT15 (615274)

MIPG (154050)

12q13.3

AD


Cerulean, cuneiform

Cataract 37; CTRCT37 (614422)

CCA5 (–)

12q24.2-q24.3

AD


Zonular pulverulent, posterior polar, nuclear coralliform, embryonal nuclear, and Coppock-like

Cataract 14, multiple types; CTRCT14 (601885)

GJA3G (121015)

13q12.11

AD


Anterior polar, or posterior polar

Cataract 32, multiple types; CTRCT32 (115650)

CTAA1 (–)

14q22-q23

AD


Central pouchlike cataract with sutural opacities

Cataract 25; CTRCT25 (605728)

CCSSO (–)

15q21-q22

AD


Infantile, lamellar, zonular, nuclear, anterior polar, stellate, pulverulent and Marner type

Cataract 5, multiple types; CTRCT5 (116800)

HSF4T (602438)

16q22.1

AD


Juvenile cortical pulverulent and later progression of posterior subcapsular, congenital cerulean, lamellar, anterior polar, nuclear, poster polar, anterior subcapsular and stellate

Cataract 21, multiple types; CTRCT21 (610202)

MAFT (177075)

16q23.2

AD

Microcornea, iris coloboma, macular hypoplasia (rare)


Anterior polar

Cataract 24, anterior polar; CTRCT24 (601202)

CTAA2 (–)

17p13

AD


Congenital zonular with sutural opacities, congenital nuclear progressive, and progressive lamellar; Y-shaped sutural

Cataract 10, multiple types; CTRCT10 (600881)

CRYBA1C (123610)

17q11.2

AD


Posterior subcapsular and central

Cataract 43; CTRCT43 (616279)

UNC45B (611220)

17q12

AD


Cerulean cataract

Cataract 7; CTRCT7 (115660)

CCA1 (–)

17q24

AD


Congenital nuclear cataract

Cataract 35, congenital nuclear; CTRCT35 (609376)

CATCN1 (–)

19q13

AR


Congenital dense white

Cataract 45; CTRCT45 (616851)

SIPA1L3 (616655)

19q13.1-q13.2

AR


Late-onset cortical pulverulent; congenital total

Cataract 19, multiple types; CTRCT19 (615277)

LIM2G (154045)

19q13.41

AR


Fluffy, cottonlike cortical; grapelike cysts in the anterior cortex

Cataract 33; CTRCT33 (611391)

BFSP1G (603307)

20p12.1

AR


Posterior polar, progressive posterior subcapsular, nuclear, and anterior subcapsular

Cataract 31, multiple types; CTRCT31 (605387)

CHMP4BG (–)

20q11.22

AD