Format

Send to

Choose Destination
Neurol Genet. 2018 Oct 24;4(6):e279. doi: 10.1212/NXG.0000000000000279. eCollection 2018 Dec.

Novel genotype-phenotype and MRI correlations in a large cohort of patients with SPG7 mutations.

Author information

1
Academic Directorate of Neurosciences (C.A.A.H., R.O'.M., M.K.R., S.P., Z.P., S.B., C.J.M., P.J.S., M.H.), Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital; Sheffield Institute for Translational Neuroscience (SITraN) (C.A.A.H., R.S., T.R., C.J.M., P.J.S., M.H.), University of Sheffield; Sheffield Diagnostic Genetics Service (N.J.B., J.M.), Sheffield Children's NHS Foundation Trust; Department of Clinical Neurophysiology (G.R., P.S.), Sheffield Teaching Hospitals NHS Foundation Trust, Royal Hallamshire Hospital; Academic Unit of Radiology (N.H.), University of Sheffield, Royal Hallamshire Hospital; and Sheffield NIHR Biomedical Research Centre for Translational Neuroscience (C.A.A.H., N.H., R.S., P.S., S.B., C.J.M., P.J.S., M.H.), United Kingdom.

Abstract

Objective:

To clinically, genetically, and radiologically characterize a large cohort of SPG7 patients.

Methods:

We used data from next-generation sequencing panels for ataxias and hereditary spastic paraplegia to identify a characteristic phenotype that helped direct genetic testing for variations in SPG7. We analyzed MRI. We reviewed all published SPG7 mutations for correlations.

Results:

We identified 42 cases with biallelic SPG7 mutations, including 7 novel mutations, including a large multi-exon deletion, representing one of the largest cohorts so far described. We identified a characteristic phenotype comprising cerebellar ataxia with prominent cerebellar dysarthria, mild lower limb spasticity, and a waddling gait, predominantly from a cohort of idiopathic ataxia. We report a rare brain MRI finding of dentate nucleus hyperintensity on T2 sequences with SPG7 mutations. We confirm that the c.1529C>T allele is frequently present in patients with long-standing British ancestry. Based on the findings of the present study and existing literature, we confirm that patients with homozygous mutations involving the M41 peptidase domain of SPG7 have a younger age at onset compared to individuals with mutations elsewhere in the gene (14 years difference, p < 0.034), whereas c.1529C>T compound heterozygous mutations are associated with a younger age at onset compared to homozygous cases (5.4 years difference, p < 0.022).

Conclusions:

Mutant SPG7 is common in sporadic ataxia. In patients with British ancestry, c.1529C>T allele represents the most frequent mutation. SPG7 mutations can be clinically predicted by the characteristic hybrid spastic-ataxic phenotype described above, along with T2 hyperintensity of the dentate nucleus on MRI.

Supplemental Content

Full text links

Icon for PubMed Central
Loading ...
Support Center