SPG15 is a rare, progressive neurological disease that is like motor neuron disease/ALS. People with SPG15 can experience progressive muscle weakness, leading to difficulty walking and become wheelchair dependant. They can also lose the ability to use their arms. With the loss of nerve cells in different parts of the brain this can lead to additional symptoms such as dementia or juvenile Parkinson’s. Some individuals with SPG15 also have problems with the retina in the eyes, this can cause visual impairment and can affect quality of life. The severity of each of these symptoms is variable in affected individuals.
SPG15, or Hereditary Spastic Paraplegia, Type 15 is a severe form of HSP, Hereditary Spastic Paraplegia. HSP is an umbrella term and have a very wide variation in onset, symptoms and nature of inheritance. As one of the many subsets of HSP, SPG15 is considered to be ultra-rare. Yet the worldwide frequency of SPG15 has not been established. It is estimated that autosomal recessive hereditary spastic paraplegias (such as SPG15) occur in approximately 1 in 50,000 births. SPG15 has been reported to account for 3 to 15% of all cases of autosomal recessive hereditary spastic paraplegias. Even though this is still extremely rare, it is likely that there are many more people living with SPG15 who are either misdiagnosed or as yet undiagnosed.
SPG15 is caused by mutations in the ZFYVE26 gene. It is a progressive autosomal recessive disease, which means that both parents have passed on a mutation to defect the gene. This gene provides instructions to make a protein called spastizin which is important in a process in which worn out cell parts and unneeded proteins are recycled within the cells. With the result of the mutations the gene is impaired and the recycling of materials within the cells is decreased so the inability to break down the cells can lead to dysfunction and often cell death.
Please take a look at this brief video explanation by Dr Jennifer Hirst from Cambridge Institute of Medical Research being interviewed by the BBC.