This unusual bile acid is also found elevated in urine and plasma from Smith-Lemli-Opitz syndrome (SLOS) patients (see below), however, Clayton and colleagues found that the UGT3A1 gene, coding 7β-hydroxy-bile acid UDP N-acetylglucosaminyl transferase, shows a common mutation, c.T361G/p.C121G, resulting in inactivity of the enzyme [54], indicating that this is not an optimal diagnostic for NP or SLOS diseases. This evidence concerns the gene UGT3A1 and Smith-Lemli-Opitz syndrome.