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Nonpenetrance of the Most Frequent Autosomal Recessive Leber Congenital Amaurosis Mutation in NMNAT1

Publicatie van: Siemiatkowska AM(1), Schuurs-Hoeijmakers JH(1), Bosch DG(2), Boonstra FN(3), Riemslag FC(4), Ruiter M(5), de Vries BB(6), den Hollander AI(7), Collin RW(1), Cremers FP(1).

Importance

The NMNAT1 gene was recently found to be mutated in a subset of patients with Leber congenital amaurosis and macular atrophy. The most prevalent NMNAT1 variant was p.Glu257Lys, which was observed in 38 of 106 alleles (35.8%). On the basis of functional assays, it was deemed a severe variant.

Observations

The p.Glu257Lys variant was 80-fold less frequent in a homozygous state in patients with Leber congenital amaurosis than predicted based on its heterozygosity frequency in the European American population. Moreover, we identified this variant in a homozygous state in a patient with no ocular abnormalities.

Conclusions and relevance

On the basis of these results, the p.Glu257Lys variant is considered not fully penetrant. Homozygotes of the p.Glu257Lys variant in most persons are therefore not associated with ocular disease. Consequently, genetic counselors should exercise great caution in the interpretation of this variant.

In: JAMA Ophthalmol. 2014 Aug 1;132(8):1002-4. doi: 10.1001/jamaophthalmol.2014.983.