EIF2AK3 and macular telangiectasia type 2: However, since PERK/ISR signaling is important for regulating serine synthesis, pharmacologic targeting of these pathways for 1-dSL-associated disorders such as MacTel is unlikely to be a promising path forward for treating patients, as downregulation of serine synthesis genes would exacerbate the underlying pathology of elevated 1-dSLs.