Spastic paraplegia 31

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Spastic paraplegia 31 (SPG31) is a rare inherited condition that mainly affects leg movement and sensation. Most people develop symptoms in childhood or around age 30. Signs include weakness in the legs, a stiff, spastic walking style, and brisk reflexes. Some people have a more complex form with extra problems such as numbness or unusual leg sensations, trouble speaking or swallowing, weakness in the hands or feet, bladder control problems, and high arches of the feet (pes cavus). Over time, nerves that control the legs can weaken, and walking may become difficult without help.

SPG31 is caused by autosomal dominant mutations in the REEP1 gene on chromosome 2. REEP1 helps make a protein that sits in brain and spinal cord cells, mainly in mitochondria, and it helps control the size of the endoplasmic reticulum and how many proteins it processes. Mutations produce a short, nonfunctional REEP1 protein, lowering the amount of working protein.

There is no cure yet, but mobility can often be improved with walking aids and physical therapy. Diagnosis involves sequencing the REEP1 gene or whole genome sequencing, along with nerve tests and a clinical examination. Autosomal dominant spastic paraplegias occur worldwide at about 1 in 100,000 people, and SPG31 makes up roughly 3–9% of these cases.