SPTLC1 and macular telangiectasia type 2: Nevertheless, the link between HSAN1 and MacTel appears to be more complex and cannot be explained by the genetic variants alone, as patients with HASN1 (age 35–71 years) who have p.Cys133Tyr and p.Cys133Trp variants (both in SPTLC1), or p.Ala182Pro variant (SPTLC2) showed no clinical signs of MacTel [13].