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). The gene discussed is FBN1; the disease is Marfan syndrome.