IMPG2

Macular Dystrophy, Vitelliform 5

Clinical Characteristics

Ocular Features:

This is a late onset form of vitelliform macular dystrophy with symptoms noted by the 5^th decade or later. Only central vision seems to be impacted and a central scotoma may be demonstrable. The ERG, EOG and color vision responses may be normal. Mild autofluorescence has been reported. The vitelliform lesions are small and may be multiple. No drusen-like lesions have been seen. Visual acuity is variable, ranging from normal to a mild decrease.

Systemic Features:

No systemic abnormalities have been reported.

Genetics

This form of vitelliform dystrophy results from heterozygous mutations in the IMPG2 gene (3q12). Patients with homozygous mutations have also been reported.

Genotyping has identified at least 5 forms of vitelliform macular dystrophy. In addition to the iconic Best disease (VMD2, 153700) apparently first described by Friedreich Best in 1905 and now attributed to mutations in the Best1 gene, we know of at least 4 more and specific mutations have been identified in three. No mutation or locus has yet been identified in VMD1 (153840) but it is likely a unique condition since mutations in other genes known to cause vitelliform dystrophy have been ruled out. Other forms are VMD3 (608161) due to mutations in the PRPH2 gene, VMD4 (616151) resulting from mutations in the IMPG1 gene, and VMD5 described here.

Pedigree:

Autosomal dominant

Autosomal recessive

Treatment

Treatment Options:

No treatment is known for the macular dystrophy. Low vision devices might be helpful for selected individuals.

References

Article Title:

Frequency and Clinical Pattern of Vitelliform Macular Dystrophy Caused by Mutations of Interphotoreceptor Matrix IMPG1 and IMPG2 Genes

Meunier I, Manes G, Bocquet B, Marquette V, Baudoin C, Puech B, Defoort-Dhellemmes S, Audo I, Verdet R, Arndt C, Zanlonghi X, Le Meur G, Dhaenens CM, Hamel CP. Frequency and Clinical Pattern of Vitelliform Macular Dystrophy Caused by Mutations of Interphotoreceptor Matrix IMPG1 and IMPG2 Genes. Ophthalmology. 2014 Dec;121(12):2406-14.

PubMed ID:

25085631

Mutations in IMPG2, encoding interphotoreceptor matrix proteoglycan 2, cause autosomal-recessive retinitis pigmentosa

Bandah-Rozenfeld D, Collin RW, Banin E, van den Born LI, Coene KL, Siemiatkowska AM, Zelinger L, Khan MI, Lefeber DJ, Erdinest I, Testa F, Simonelli F, Voesenek K, Blokland EA, Strom TM, Klaver CC, Qamar R, Banfi S, Cremers FP, Sharon D, den Hollander AI. Mutations in IMPG2, encoding interphotoreceptor matrix proteoglycan 2, cause autosomal-recessive retinitis pigmentosa. Am J Hum Genet. 2010 Aug 13;87(2):199-208.

PubMed ID:

20673862

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