Germline alterations in phosphatase and tensin homolog (PTEN; PTEN_mut+), succinate dehydrogenase B/C/D (SDHB-D; SDHx_var+), and killin (KLLN_Me+) cause CS and Cowden syndrome-like (CSL) phenotypes.
Germline variants in SDHB/C/D (SDHx) genes account for subsets of CS/CS-like cases, conferring a higher risk of breast and thyroid cancers over those with only germline PTEN mutations.
Germline variations in succinate dehydrogenase genes (SDHx) occur in approximately 10% PTEN mutation-negative CS and CS-like (CSL) individuals (SDH(var+)).
Compared to PTEN mutation-positive CS/CS-like individuals, those with SDH mutations/variants were enriched for carcinomas of the female breast (6/9 SDH versus 30/107 PTEN, p < 0.001), thyroid (5/10 versus 15/106, p < 0.001), and kidney (2/10 versus 4/230, p = 0.026).