At a minimum, these SNPs are known to be related, and others may also be
Gerstmann–Straussler–Scheinker syndrome (GSS) is a very rare, usually familial, fatal neurodegenerative disease that affects patients from 20 to 60 years in age. Though exclusively heritable, this extremely rare disease is classified with the transmissible spongiform encephalopathies (TSE) due to the causative role played by PRNP, the human prion protein.Wikipedia
Familial cases are associated with autosomal-dominant inheritance. Gerstmann–Straussler–Scheinker disease (GSS) is an extremely rare neurogenetic brain disorder. It is always inherited and is found in only a few families all over the world (according to NINDS). The trait is an autosomal-dominant trait caused by a gene mutation. It is also in a group of hereditary prion protein diseases or also known as TSEs. Many symptoms are associated with GSS, such as progressive ataxia, pyramidal signs, and even adult-onset dementia; they progress more as the disease progresses. Wikipedia
A 2017 book, Mercies in Disguise, by NY Times science writer Gina Kolata, tells the story of the Baxley family members as they learn of the GSS mutation in their families.