CRYBB2 gene

• Overview
• Congenital cataracts
• Additional information
• References

Overview

Gene (OMIM No.)	CRYBB2 (#123620)
Function of gene/protein	Protein: crystallin beta B2 Lens-specific protein with structural and functional components Involved in lens development Functions as a molecular chaperone in its oxidised form
Clinical phenotype (OMIM phenotype no.)	Cataract 3, multiple types (#601547)
Inheritance	Autosomal dominant
Ocular features	Congenital cataracts (Coppock-like, cerulean)
Systemic features	No extraocular features have been reported
Key investigations	B-scan USS to measure axial length to document microphthalmia and detect any posterior segment abnormalities Electrophysiology TORCH screen MRI brain and orbit Assessment with a paediatrician if suspicious of systemic involvement
Molecular diagnosis	Next generation sequencing Targeted gene panels (cataract) Whole exome sequencing Whole genome sequencing
Management	Ocular Management of congenital cataract
Therapies under research	None at present
Further information	OMIM

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Additional information

In the first pedigree of autosomal dominant congenital cerulean cataract reported by Bodker et al and subsequently by Kramer et al, a female (individual #102) who was product of a consanguineous marriage between two affected cousins, displayed congenital cataract, microphthalmia and microcornea.^[3,4] All other affected family members only had isolated cataract with mild visual symptoms in their childhood and early adolescence. Individual #102 required cataract extraction at age 5 years and loss her vision later in adulthood due to bilateral band keratopathy and corneal neovascularisation. Litt et al later identified that she harboured a homozygous truncating p.Gln155Ter mutation while the other affected family members were heterozygous, thus representing a rare example of homozygosity for a dominant mutation.^[5]

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References

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