Bronwyn E Grinton, Colin A Ellis, Mered Parnes, Laina Lusk Stripe, Jacob E Munro, Laure Mazzola, Pamela P McDonnell, Betül Baykan, Volkan Taşdemir, Mariam Hull, Krystal Sully, Sara Cabet, Anna-Elina Lehesjoki, Nerses Bebek, Melanie Bahlo, Samuel F Berkovic, Gaetan Lesca, Karen L Oliver
Our findings strengthen the previous evidence for SLC7A6OS as a cause of PME and highlight a founder effect in regions with migratory links to Iberia. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.
BACKGROUND: SLC7A6OS c.191A>G is a rare, autosomal recessive cause of progressive myoclonus epilepsy (PME). The c.191A>G variant, first discovered in two families from Türkiye and Portugal, was recently identified in three additional probands from the USA, all of Puerto Rican ancestry.
OBJECTIVES: We sought to refine the SLC7A6OS-PME phenotype and determine whether all families inherited the variant from the same common ancestor.
METHODS: Clinical and genotyping data were obtained from all five families. Haplotype analysis using single nucleotide polymorphism arrays to investigate a possible common ancestor was performed.
RESULTS: Shared haplotypes suggest all five families inherited the SLC7A6OS variant from a common ancestor approximately 1100 years ago. Subsequent dating estimates were consistent with migration patterns between the eastern Mediterranean, Iberia, and Puerto Rico.
CONCLUSIONS: Our findings strengthen the previous evidence for SLC7A6OS as a cause of PME and highlight a founder effect in regions with migratory links to Iberia. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.