Molar pregnancies are abnormal pregnancies in which the placenta develops excessively and there is no normal fetal development. They are important because molar tissue can easily develop into a placental tumour for which the patient would need chemotherapy. Molar pregnancies are usually chance (sporadic) occurrences but occasionally women have an inherited predisposition to these pregnancies because they have mutations in both copies of a gene called NLRP7. We have investigated this gene in women with sporadic molar pregnancies and shown that these women do not have mutations in the gene and that mutations in this gene are not responsible for most molar pregnancies. (By Dr Rosemary A Fisher, http://jmg.bmj.com/content/49/3/206 )