Do GWAS and studies of heterozygotes for NPC1 and/or NPC2 explain why NPC disease cases are so rare?

Do GWAS and studies of heterozygotes for NPC1 and/or NPC2 explain why NPC disease cases are so rare? J Appl Genet. 2018 Sep 13;: Authors: Erickson RP Abstract Early onset Niemann-Pick C diseases are extremely rare, especially Niemann-Pick C2. Perhaps unusually for autosomal recessive diseases, heterozygotes for mutations in NPC1 manifest many biological variations. NPC2 deficiency has large effects on fertility. These features of NPC1 and NPC2 are reviewed in regard to possible negative selection for heterozygotes carrying null and hypomorphic alleles. PMID: 30209687 [PubMed - as supplied by publisher]
Source: J Appl Genet - Category: Genetics & Stem Cells Authors: Tags: J Appl Genet Source Type: research