B3GALNT2 gene

• Overview
• Microphthalmia, anophthalmia, coloboma (MAC)
• Congenital cataracts
• Anterior segment dysgenesis
• Congenital glaucoma
• References

Overview

Gene (OMIM No.)	B3GALNT2 (#610194)
Function of gene/protein	Protein: beta-1,3-N-acetylgalactosaminyltransferase 2 An enzyme involved in the glycosylation (converting carbohydrates to glycoproteins) of alpha-dystroglycan DAG1
Clinical phenotype (OMIM phenotype no.)	Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 11 (#615181) Also known as Walker-Warburg syndrome (WWS)/Muscle Eye Brain Disease (MEB) Defects in the glycosylation of alpha-dystroglycans cause 3 overlapping syndromes/dystroglycanopathies: WWS, MEB and Fukuyama type Congenital Muscular Dystrophy (FCMD; #253800) WWS—most severe phenotype; MEB—intermediate phenotype; FCMD—mildest phenotype Phenotype severity is determined by the extent which the mutation affects DAG1 glycosylation
Inheritance	Autosomal recessive
Ocular features	Microphthalmia, anophthalmia, coloboma (MAC) spectrum Congenital cataracts Anterior segment dysgenesis Congenital glaucoma Persistent foetal vasculature Retinal dysplasia Retinal detachment Optic atrophy High myopia
Systemic features	Congenital muscular dystrophy Brain anomalies (cobblestone lissencephaly, hydrocephalus, hypoplastic cerebellar vermis, macrocephaly, microcephaly or anencephaly) Severe hypotonia Occasional seizures Intellectual disability Developmental delays Patients with WWS have a severely limited lifespan with significant CNS and ocular anomalies
Key investigations	B-scan USS to measure axial length to document microphthalmia Electrophysiology to determine visual potential Gonioscopy (if tolerated/EUA) or anterior segment OCT to identify angle abnormalities and any associated anterior segment dysgenesis MRI brain and orbit Systemic assessment with a paediatrician and other relevant specialists Bloods (elevated creatinine kinase) Skeletal muscle biopsy
Molecular diagnosis	Next generation sequencing Targeted gene panels Whole genome sequencing
Management	Ocular Management of MAC Management of congenital cataract Management of anterior segment dysgenesis Management of congenital glaucoma Surgery for dysplastic retina does not confer any visual benefit Rhegmatogenous retinal detachment associated with MEB may be amenable to scleral buckling or vitrectomies Systemic Multidisciplinary approach
Therapies under research	None at present
Further information	OMIM

Jump to top

---

References

Jump to top