Regional brain volume abnormalities in Lesch-Nyhan disease and its variants: a cross-sectional study

Abstract

Background: Lesch-Nyhan disease is a rare, X-linked, neurodevelopmental metabolic disorder that is caused by abnormalities in the levels of hypoxanthine-guanine phosphoribosyltransferase enzyme activity. The neural substrates associated with Lesch-Nyhan disease remain poorly understood. We aimed to use voxel-based morphometry to identify affected brain regions in classic Lesch-Nyhan disease and Lesch-Nyhan variant disease, and to identify regions that differ between the two disease types.

Methods: In this cross-sectional study, we recruited patients with classic Lesch-Nyhan disease or Lesch-Nyhan variant disease from clinics, referrals, the Lesch-Nyhan Syndrome Registry, and the Matheny School and Hospital (Peapack, NJ, USA), and healthy controls from the Baltimore metropolitan area (MD, USA). We used voxel-based morphometry to analyse grey matter volume between groups using a three-group ANCOVA, followed by six pairwise post-hoc group comparisons.

Findings: Between Oct 3, 1993, and April 29, 2013, we recruited 21 patients with classic Lesch-Nyhan disease, 17 patients with variant disease, and 33 healthy controls. Patients with classic Lesch-Nyhan disease had a 20% reduction in intracranial volume (17% reduction in grey matter volume; 26% reduction in white matter volume) compared with healthy adults. The largest differences were in basal ganglia, and frontotemporal and limbic regions, with sparing of parieto-occipital regions. Grey matter volumes of patients with Lesch-Nyhan variant disease were invariably between those of patients with classic Lesch-Nyhan disease and healthy controls. Compared with healthy controls, patients with classic disease showed additional grey matter volume reductions in the temporal lobe and left lateralised structures, and patients with variant disease showed additional reductions in lingual and precuneus regions with sparing of right frontal and temporal regions. Patients with classic disease had reductions of volume in the ventral striatum and prefrontal areas compared with those with the variant form.

Interpretation: We noted regional abnormalities associated with known neurological and behavioural deficits in patients with classic Lesch-Nyhan disease. Patients with Lesch-Nyhan variant disease show milder grey matter abnormalities in many of the same brain regions and preservation of grey matter volume in other regions, which could provide important clues to the neural substrates of differences between the phenotypes.

Funding: National Institute of Child Health and Human Development, Therapeutic Cognitive Neuroscience Fund, and Benjamin and Adith Miller Family Endowment on Aging, Alzheimer's and Autism Research.

Figure 1

Axial slice view of the results of ANCOVA. Note that the greatest abnormalities involve the basal ganglia, frontal, temporal and limbic regions with near complete sparing of the occipital and parietal lobes. (Neurological Convention, p<.0005, FWE <.01, single subject T1 template image)

Figure 2

Gray matter volumes in clusters significant for the F-contrast across all three groups.

Figure 3

Axial slice view gray matter volume abnormalities identified by post-hoc comparisons, number indicates z value. (red HC > LND; blue HC > LNV; green LNV > LND) (Neurological Convention, p<.001, FWE <.05, skull stripped average template)

Figure 4

Scatterplot showing partial correlation (controlling for age) of Burke-Fahn-Marsden (BFM) dystonia severity ratings and basal ganglia volumes for patients with LND and LNV.