title: Retinal Structure in Cobalamin C Disease: Mechanistic and Therapeutic Implications.
abstract: OBJECTIVE
  To describe the retinal structure in a patient with cobalamin C (cblC) disease.
  
  
  METHODS
  A 13-year-old male patient diagnosed with cblC disease during a perinatal metabolic screening prompted by jaundice and hypotony underwent ophthalmic examinations, electroretinography (ERG) and spectral domain optical coherence tomography (SD-OCT).
  
  
  RESULTS
  The patient carried a homozygous (c.271dupA) mutation in the methylmalonic aciduria and homocystinuria type C (MMACHC) gene. At age 3 months he had a normal eye exam. A pigmentary maculopathy progressed to chorioretinal atrophy from 5-10 months. ERG at 7 months was normal. A nystagmus remained stable since the age of 2 years. At age 13, visual acuity was 20/250 (right eye) and 20/400 (left eye), with a +5.00 D correction, a level of vision maintained since first measurable at age 5 years. SD-OCT showed bilateral macular coloboma-like lesions; there was also a thickened surface layer with ganglion cell layer thinning. Photoreceptor outer segment loss and thinning of the outer nuclear layer (ONL) transitioned to regions with no discernible ONL with a delaminated, thickened, inner retina.
  
  
  CONCLUSIONS
  A thick surface layer near the optic nerve resembling an immature retina and an initially normal macula that rapidly developed coloboma-like lesions suggest there may be an interference with retinal/foveal development in cblC, a mechanism of maculopathy that may be shared by other early onset retinal degenerations. Photoreceptor loss and inner retinal remodeling confirm associated photoreceptor degeneration.
authors: a Scheie Eye Institute and.
authors: Tomas S
authors: TS
authors: Aleman
authors: a Scheie Eye Institute and.
authors: Frank
authors: F
authors: Brodie
authors: b Children's Hospital of Philadelphia, Department of Ophthalmology, University of Pennsylvania , and.
authors: Christopher
authors: C
authors: Garvin
authors: a Scheie Eye Institute and.
authors: Dina Y
authors: DY
authors: Gewaily
authors: c Section of Metabolism (Biochemical Genetics), The Children's Hospital of Philadelphia, University of Pennsylvania , Philadelphia , PA , USA.
authors: Can H
authors: CH
authors: Ficicioglu
authors: b Children's Hospital of Philadelphia, Department of Ophthalmology, University of Pennsylvania , and.
authors: Monte D
authors: MD
authors: Mills
authors: b Children's Hospital of Philadelphia, Department of Ophthalmology, University of Pennsylvania , and.
authors: Brian J
authors: BJ
authors: Forbes
authors: a Scheie Eye Institute and.|b Children's Hospital of Philadelphia, Department of Ophthalmology, University of Pennsylvania , and.
authors: Albert M
authors: AM
authors: Maguire
authors: b Children's Hospital of Philadelphia, Department of Ophthalmology, University of Pennsylvania , and.
authors: Stefanie L
authors: SL
authors: Davidson
mesh_terms: D000293:Adolescent; D002352:Carrier Proteins / Q000235:genetics; D004596:Electroretinography; D006712:Homocystinuria / Q000175:diagnosis* / Q000235:genetics; D006801:Humans; D008297:Male; D010088:Oxidoreductases; D012160:Retina / Q000473:pathology*; D012162:Retinal Degeneration / Q000175:diagnosis* / Q000235:genetics; D012165:Retinal Ganglion Cells / Q000473:pathology; D055214:Retinal Photoreceptor Cell Outer Segment / Q000473:pathology; D041623:Tomography, Optical Coherence; D014792:Visual Acuity; D014806:Vitamin B 12 Deficiency / Q000151:congenital* / Q000175:diagnosis / Q000235:genetics
chemical_list: D002352:Carrier Proteins; C508359:MMACHC protein, human; D010088:Oxidoreductases
keywords: Cobalamin C; coloboma; optical coherence tomography; photoreceptors