Welander distal myopathy (WDM) is a rare autosomal dominant inherited muscular dystrophy.1 WDM patients share an unusual haplotype on chromosome 2p13, where a heterozygous missense founder mutation (c.1362G > A; p.E384K; substitution of glutamic acid for lysine in the protein) has been identified in TIA1, an RNA-binding protein and a core component of stress granules (SGs).2 SGs are stress-induced non-membranous cytoplasmic aggregates from proteins and RNAs.3 The effects of the WDM-TIA1 mutation have been associated with abnormalities in the dynamics of TIA1-dependent SGs.2 Although its genetic cause is known, WDM is poorly understood. Understanding the WDM-associated molecular mechanisms, particularly the alterations in cellular homeostasis, is essential to identify therapeutic opportunities. Here, we sought to elucidate the molecular and cellular defects associated with mutant TIA1 expression, which may be partly responsible for the deficiencies observed in WDM patients.