Infantile retinopathy in the Cobalamin C methylmalonic aciduria and homocystinuria

Poster Details

First Author: C.Hernández Martínez SPAIN

Co Author(s):    D. Martinez Martinez   I. Yago Ugarte   P. Perez Fernandez   J. Marian Sanchez                    

Abstract Details


Cobalamin C methylmalonic aciduria and homocystinuria is the most common inherited disorder of vitamin B12 metabolism. Maculopathy, pigmentary retinopathy, and optic nerve atrophy has been described. We report the clinical and neurophysiological characteristics of a 9-year-old girl with Cobalamin C methylmalonic aciduria and homocystinuria.


The 9-year-old patient has been diagnosed and treated at the General University Hospital 'Virgen de la Arrixaca' in Murcia (Spain).


The diagnosis was confirmed by biochemical laboratory testing and genetic analysis. We completed the ophthalmologic study with best-corrected visual acuity, slit-lamp biomicroscopy, dilated fundus examination with retinographies, optical coherence tomography (OCT), and electrophysiology.


The 9-year-old girl at the present time has a visual acuity of counting fingers at 1 metre. A sensorial nystagmus with alternating exotropia has developed and in the fundus of the eye we observed a severe maculopathy with chorioretinal atrophy, peripheral bone spicules and vascular attenuation. A severe involvement of cones and rods was shown with the scopic, phothotopic and flicker electroretinogram. OCT images demonstrated extreme thinning of the retina. The genetic analysis confirmed the mutations in the MMACHC gene. No lens dislocation despite hyperhomocysteinemia was seen.


Cobalamin C methylmalonic aciduria and homocystinuria is a rare vitamin B12 metabolism disease. Its clinical manifestations include feeding difficulties, neural dysfunction and opthalmologic abnormalities including visual impairment, nystagmus and infantile retinopathy with severe maculopathy. Dietary supplements with hydroxocobalamin appear to attenuate the ocular disease.

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