Neuroradiological, neurophysiological and molecular findings in infantile Krabbe disease: two case reports

Abstract

Krabbe disease is an autosomal recessive neurodegenerative disorder due to a defect of the lysosomal enzyme β-galactocerebrosidase (β-GALC). Depending on the age of onset, the disease is classified into infantile and later-onset forms. We report neuroradiological, neurophysiological and molecular findings in two Greek patients with the infantile form of Krabbe disease. The index patients presented at the age of 3.5 and 6 months, respectively, due to developmental delay. Magnetic resonance imaging (MRI) of the first patient's brain demonstrated signs of leukodystrophy, while nerve conduction velocities (NCVs) were significantly decreased. The second patient's MRI at the age of 4 months was initially normal, but at 18 months demonstrated leukodystrophic alterations as well, whereas NCVs were also significantly delayed. In both patients, a severe decrease in β-GALC, activity supported the diagnosis of Krabbe disease, while the final diagnosis was confirmed by molecular genetic testing. Two homozygous mutations of the GALC gene, the c.411_413delTAA [p.K139del] mutation in the first patient, and the c.749T>C [p.I250T] mutation in the second patient, were identified. At their last follow-up visit at the age of 4 and 6 years, respectively, both patients were bedridden and quadri-plegic, suffering from frequent respiratory tract infections and fed through a gastrostomy. Both mutations found in homozygosity in these two unrelated patients of Greek ancestry, could pinpoint a common origin. Genotyping of patients with Krabbe disease is important, in order to contribute to the creation of a European mutation database and to further study possible genotype-phenotype correlations of the disease.

Keywords: GALC gene; Krabbe disease; Leukodystrophy; Mutation; Nerve conduction velocity (NCV); β-galactocerebrosidase (β-GALC).

Figure 1

Brain MRI of the first patient at the age of 3.5 months (T2 weighted sequences TR/TE 4000/99). Note the mildly increased signal in the posterior limbs of the internal capsule bilaterally and in the white matter of the occipital lobe.

Figure 2

Brain MRI of second patient at the age of 18 months (T2 weighted sequences TR/TE 4510/119). Note the increased signal in the periventicular white matter around the occipital horns of the lateral ventricles with enlargement of both lateral ventricles and the subarachnoid spaces.