Patisiran exposure in early pregnancy: a case report.

We describe here the first case of exposure to patisiran treatment, a small interfering RNA molecule, during early pregnancy of a 36-year-old woman with symptomatic hereditary transthyretin-related amyloidosis. There were no major complications during pregnancy and delivery, except for a postpartum hemorrhage due to uterine atony. Vitamin A levels had to be closely monitored during pregnancy, and vitamin A substitution adapted accordingly. There was no sign of minor or major congenital abnormalities of the baby. One month after delivery, the patient showed slight clinical and electrophysiological signs of neuropathy progression due to patisiran treatment withdrawal. Patisiran infusions were resumed 3 months after delivery. Due to the unknown teratogenic potential of patisiran, the risk of neuropathy worsening associated with withholding treatment must of course be weighed against a potential teratogenic risk of treatment during pregnancy. Vitamin A levels need to be closely assessed, and substitution must be adapted accordingly, to avoid embryofetal adverse outcome due to vitamin A deficiency or toxicity.