@article {192, title = {Whole Exome Sequencing Identifies an Adult-Onset Case of Methylmalonic Aciduria and Homocystinuria Type C (cblC) with Non-Syndromic Bull{\textquoteright}s Eye Maculopathy.}, journal = {Ophthalmic Genet}, volume = {36}, year = {2015}, month = {2015}, pages = {270-5}, abstract = {

BACKGROUND: Methylmalonic aciduria and homocystinuria type C (cblC), a disorder of vitamin B12 (cobalamin) metabolism caused by mutations in the MMACHC gene, presents with many systemic symptoms, including neurological, cognitive, psychiatric, and thromboembolic events. Retinal phenotypes, including maculopathy, pigmentary retinopathy, and optic atrophy are common in early onset form of the disease but are rare in adult onset forms.

MATERIALS AND METHODS: An adult Hispanic female presented with decreased central vision, bilateral pericentral ring scotomas and bull{\textquoteright}s eye-appearing macular lesions at 28 years of age. Her medical history was otherwise unremarkable except for iron deficiency anemia and both urinary tract and kidney infections. Screening of the ABCA4 gene, mutations in which frequently cause bull{\textquoteright}s eye maculopathy, was negative. Subsequently, analysis with whole exome sequencing was performed.

RESULTS: Whole exome sequencing discovered compound heterozygous mutations in MMACHC, c.G482A:p.Arg161Gln and c.270_271insA:p.Arg91Lysfs*14, which segregated with the disease in the family. The genetic diagnosis was confirmed by biochemical laboratory testing, showing highly elevated urine methylmalonic acid/creatinine and homocysteine levels, and suggesting disease management with hydroxycobalamin injections and carnitine supplementation.

CONCLUSIONS: In summary, a unique case of an adult patient with bull{\textquoteright}s eye macular lesions and no clinically relevant systemic symptoms was diagnosed with cblC by genetic screening and follow-up biochemical laboratory tests.

}, keywords = {Adult, Carrier Proteins, Electroretinography, Exome, Female, Genetic Testing, Heterozygote, Homocystinuria, Humans, Macular Degeneration, Mutation, Pedigree, Scotoma, Sequence Analysis, DNA, Tomography, Optical Coherence, Visual Acuity, Visual Fields, Vitamin B 12, Vitamin B 12 Deficiency, Vitamin B Complex}, issn = {1744-5094}, doi = {10.3109/13816810.2015.1010736}, author = {Collison, Frederick T and Xie, Yajing Angela and Gambin, Tomasz and Jhangiani, Shalini and Muzny, Donna and Gibbs, Richard and Lupski, James R and Fishman, Gerald A and Allikmets, Rando} } @article {242, title = {New syndrome with retinitis pigmentosa is caused by nonsense mutations in retinol dehydrogenase RDH11.}, journal = {Hum Mol Genet}, volume = {23}, year = {2014}, month = {2014 Nov 01}, pages = {5774-80}, abstract = {

Retinitis pigmentosa (RP), a genetically heterogeneous group of retinopathies that occur in both non-syndromic and syndromic forms, is caused by mutations in \~{}100 genes. Although recent advances in next-generation sequencing have aided in the discovery of novel RP genes, a number of the underlying contributing genes and loci remain to be identified. We investigated three siblings, born to asymptomatic parents of Italian-American descent, who each presented with atypical RP with systemic features, including facial dysmorphologies, psychomotor developmental delays recognized since early childhood, learning disabilities and short stature. RP-associated ophthalmological findings included salt-and-pepper retinopathy, attenuation of the arterioles and generalized rod-cone dysfunction as determined by almost extinguished electroretinogram in 2 of 3 siblings. Atypical for RP features included mottled macula at an early age and peripapillary sparing of the retinal pigment epithelium. Whole-exome sequencing data, queried under a recessive model of inheritance, identified compound heterozygous stop mutations, c.C199T:p.R67* and c.C322T:p.R108*, in the retinol dehydrogenase 11 (RDH11) gene, resulting in a non-functional protein, in all affected children. In summary, deleterious mutations in RDH11, an important enzyme for vision-related and systemic retinoic acid metabolism, cause a new syndrome with RP.

}, keywords = {Adolescent, Child, Codon, Nonsense, Female, Humans, Male, Oxidoreductases, Pedigree, Phenotype, Retinitis Pigmentosa, Syndrome, Vision Tests, Visual Acuity, Young Adult}, issn = {1460-2083}, doi = {10.1093/hmg/ddu291}, author = {Xie, Yajing Angela and Lee, Winston and Cai, Carolyn and Gambin, Tomasz and N{\~o}upuu, Kalev and Sujirakul, Tharikarn and Ayuso, Carmen and Jhangiani, Shalini and Muzny, Donna and Boerwinkle, Eric and Gibbs, Richard and Greenstein, Vivienne C and Lupski, James R and Tsang, Stephen H and Allikmets, Rando} }