Five genetic diseases (and their associated genes) for which diagnosis codes have been found to be of high positive predictive value in EHRs58, were examined: Marfan syndrome (FBN1 and TGFBR1), multiple endocrine neoplasia (MEN1 and RET), neurofibromatosis (NF2), paragangliomas (SDHAF2, SDHB, SDHC), and tuberous sclerosis (TSC1, TSC2). This evidence concerns the gene SDHB and Marfan syndrome.