Control levels of 7-OC were found to be 3.8–39.8 ng/ml (2.5th to 97.5th percentile) with a median of 16.1 ng/ml (n = 135), in NPC the median was 86 ng/ml (n = 16, range 21.9–963 ng/ml), in NPB only two patients were analysed where 7-OC was 62.8–383 ng/ml, in two LAL deficiency patients 7-OC was 35.5–103 ng/ml and in SLOS patients, the median was 139 ng/ml (n = 4, range 76.4–337 ng/ml). Here, BGLAP is linked to nasopharyngeal carcinoma.