Novel Compound Heterozygous SPG7 Mutation Mimicking Amyotrophic Lateral Sclerosis
Matthew Doward1, Andre Granger1
1Mayo Clinic
Objective:
N/A
Background:
Hereditary spastic paraplegia type 7 (HSP7) is a complex autosomal recessive disease. It can present as pure spastic paraplegia. It can also involve features outside of the lower limbs such as sphincter dysfunction, spastic dysarthria, dysphagia, nystagmus, amyotrophy, and optic atrophy.
Design/Methods:
Review of patient chart and the literature.
Results:
A middle-aged man presented for progressive weakness and stiffness of his lower limbs with gait imbalance for 2 years. He also reported arm weakness, occasional dysphagia, and weight loss. Exam revealed symmetric mild proximal and distal weakness in the lower limbs, diffuse upper and lower limb hyperreflexia, rare fasciculations of upper and lower limbs, and mild atrophy of left calf and left hand muscles. Serum neurofilament light chain and CK were normal. Cerebrospinal fluid analysis was normal. MRI brain and total spine revealed no significant findings. Two consecutive EMGs demonstrated an evolving chronic and active neurogenic process in the lumbosacral segment. Genetic testing for inherited causes of motor neuron disease and Hereditary Spastic Paraplegia panel revealed two pathogenic heterozygous variants in SPG7, c.1529C>T and c.861+2dup (intronic), which had not been previously reported. His asymptomatic mother was found to only have the heterozygous pathogenic c.1529C>T variant. Subsequent neuro-ophthalmologic exam revealed bilateral optic atrophy. Over time, his symptoms have slowly progressed, though partially responsive to Baclofen, and he continues to follow with physical therapy and ophthalmology.
Conclusions:
Symptoms in patients with HSP7 may overlap with those of amyotrophic lateral sclerosis (ALS) patients. Factors differentiating HSP7 from ALS are primary involvement of the lower extremities, slow symptom progression, optic atrophy, and significant urinary bladder dysfunction and spasticity. Muscle atrophy, fasciculations, weakness in the arms, and dysphagia are typically more common in ALS.
10.1212/WNL.0000000000215000
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