The agency hire comes in advance of the UK launch of its fertility test - Fertell - in the early autumn (PRWeek, 8 April).
The agency saw off Manning Selvage & Lee in a final two-way shootout for the business, with agencies including Munro & Forster Communications also having discussions with Genosis in the early stages of the agency selection process.
Fertell is an over-the-counter test that aims to help couples monitor their fertility and improve the chances of conception.
H&K has put a cross-disciplinary team on the business, and is targeting the healthcare professional media, plus consumer audiences.
Agency head of marketing and comms Wendy Mair is one of the agency staff working on the account.
US-based Genosis operates in the UK via a Surrey-headquartered subsidiary.
It spoke to around ten agencies initially.