SIL1 is a nucleotide exchange factor that plays a critical role in endoplasmic reticulum (ER) protein homeostasis by regulating the HSP70 chaperone BiP (HSPA5) 1. SIL1 functions alongside GRP170 as one of two nucleotide exchange factors that facilitate BiP's ATP-ADP cycle, enabling proper protein folding and translocation in the ER lumen 23. The protein is essential for maintaining ER homeostasis through its regulation of BiP's chaperone activity in protein quality control pathways 1. Loss-of-function mutations in SIL1 cause Marinesco-Sjögren syndrome (MSS), a rare autosomal recessive multisystem disorder characterized by congenital cataracts, cerebellar ataxia, and vacuolar myopathy 1. Recent research has expanded the clinical spectrum of SIL1 deficiency to include peripheral nervous system abnormalities, with studies showing degenerative changes in peripheral nerves and neuromuscular junctions in both animal models and MSS patients 4. Additionally, SIL1 appears to have neuroprotective functions, as overexpression has been shown to improve cognitive impairment in Alzheimer's disease models by regulating amyloid precursor protein processing 5. The protein's involvement in neurological pathways is further supported by genome-wide association studies linking SIL1 variants to chr5 cough phenotypes 6.