A new paraplegin mutation in a patient with primary progressive multiple sclerosis

Multiple sclerosis in patients with hereditary spastic paraplegia: a case report and systematic review

INTRODUCTION

An increasing number of cases of comorbid hereditary spastic paraplegia (HSP) and multiple sclerosis (MS) have been described. We report a patient with the SPG3A form of HSP and features of relapsing-remitting MS (RRMS). We took this opportunity to review the current literature of co-occurring MS and HSP.

METHOD

The patient underwent clinical, laboratory and neuroimaging evaluations. We performed a literature search for cases of HSP and MS. The 2017 McDonalds Criteria for MS were retrospectively applied to the selected cases.

RESULTS

A 34-year-old woman, presenting a molecular diagnosis of SPG3A, complained subacute sensory-motor symptoms. Spinal MRI disclosed T2-hyperintense lesions at C2, T6 and T4 level, the latter presenting contrast-enhancement. CSF analysis showed oligoclonal bands. She was treated with intravenous high-dose steroids, with symptom resolution. The literature review yielded 13 papers reporting 20 possible cases of MS and HSP. Nine patients (5 M, median age 34) met the 2017 McDonald criteria. Five (25%) received a diagnosis of RRMS and four (20%) of primary progressive MS. Brain MRI showed multiple WM lesions, mostly periventricular. Six of seven cases (85.7%) had spinal cord involvement. Oligoclonal bands were found in 6/8 (75%) patients. Seven patients (77.7%) improved/stabilized on immunotherapy.

CONCLUSION

This is the first description on the association between SPG3A type of HSP and MS. This report adds to the other reported cases of co-occurring HSPs and MS. Although it remains unclear if this association is casual or causal, clinicians should be aware that an HSP diagnosis does not always exclude a concomitant MS.

Evidence for Non-Mendelian Inheritance in Spastic Paraplegia 7

BACKGROUND

Although the typical inheritance of spastic paraplegia 7 is recessive, several reports have suggested that SPG7 variants may also cause autosomal dominant hereditary spastic paraplegia (HSP).

OBJECTIVES

We aimed to conduct an exome-wide genetic analysis on a large Canadian cohort of HSP patients and controls to examine the association of SPG7 and HSP.

METHODS

We analyzed 585 HSP patients from 372 families and 1175 controls, including 580 unrelated individuals. Whole-exome sequencing was performed on 400 HSP patients (291 index cases) and all 1175 controls.

RESULTS

The frequency of heterozygous pathogenic/likely pathogenic SPG7 variants (4.8%) among unrelated HSP patients was higher than among unrelated controls (1.7%; OR 2.88, 95% CI 1.24-6.66, P = 0.009). The heterozygous SPG7 p.(Ala510Val) variant was found in 3.7% of index patients versus 0.85% in unrelated controls (OR 4.42, 95% CI 1.49-13.07, P = 0.005). Similar results were obtained after including only genetically-undiagnosed patients. We identified four heterozygous SPG7 variant carriers with an additional pathogenic variant in known HSP genes, compared to zero in controls (OR 19.58, 95% CI 1.05-365.13, P = 0.0031), indicating potential digenic inheritance. We further identified four families with heterozygous variants in SPG7 and SPG7-interacting genes (CACNA1A, AFG3L2, and MORC2). Of these, there is especially compelling evidence for epistasis between SPG7 and AFG3L2. The p.(Ile705Thr) variant in AFG3L2 is located at the interface between hexamer subunits, in a hotspot of mutations associated with spinocerebellar ataxia type 28 that affect its proteolytic function.

CONCLUSIONS

Our results provide evidence for complex inheritance in SPG7-associated HSP, which may include recessive and possibly dominant and digenic/epistasis forms of inheritance. © 2021 International Parkinson and Movement Disorder Society.