Everyday Health scooped up rare-disease advertising agency Cambridge BioMarketing in a deal worth around $38 million.

The transaction, announced Monday, builds on the marketing opportunity previously identified by Everyday Health in small-population conditions, a position reinforced by the FDA’s growing number of rare-disease drug approvals. Rare diseases are defined as conditions that affect fewer than 200,000 patients.

The companies backing rare-disease drugs are big players: Cambridge’s client roster includes AstraZeneca and Bristol-Myers Squibb, for which it launched the drug Myalept for lipodystrophy. The firm, which saw its head count rise from 40 in 2012 to around 70 in 2015, is also responsible for launching BioMarin’s enzyme-replacement therapy Vimizim for the condition Morquio A Syndrome. The FDA said in a blog post that the Morquio A patient group is around 1,000 patients.

Cambridge CEO Maureen Franco told MM&M in an interview that the agency had been looking for a partner for the past year and that Everyday Health properties such as MayoClinic.org and MedPage Today “align with our client strategy and our brand.” She added that Everyday Health has what she called a “digital depth” that will enhance what Cambridge can offer its clients. She said the new owner “is very mission-driven … they feel like us.” Franco will keep her CEO title after the deal closes and the local staff is expected to stay in place.

The deal adds data and measurement tools to Cambridge’s assets. The purchase is expected to boost Everyday Health’s 2015 revenues to between $234 million and $242 million, compared to the $221 million to $228 million range it forecast earlier.

The deal is a combination of $25 million in cash, $8 million in cash or stock and up to an additional $5 million in milestones.

The deal will result in rare-disease marketing and education for both patients and physicians, without one necessarily outweighing the other, Reshma Rughwani, Everyday Health’s EVP of commercialization and product strategy, told MM&M. She noted that failing to address both would be “to miss a big part of the challenge” of reaching these rare-disease patient communities.

She also said that the rare-disease space has been underserved not just in terms of pharmaceuticals but with respect to materials for patients and physicians as well. She said adding Cambridge to its offerings is “very compelling from a pharma-client perspective,” particularly because the rare-disease and orphan-drug category is expected to grow. Research firm EvaluatePharma has projected that rare-disease drugs will account for 19% of prescriptions, or $176 billion in sales, by 2020.

Rughwani, who joined Everyday Health just six months ago, is part of an ongoing shift at the brand that includes bringing on former Publicis Healthcare Communications Group co-president Michael du Toit last month, as well as going public and buying marketing firm DoctorDirectory.com last year. The company said in its annual report that this latter move allows the brand to reach more than 66% of US doctors.