DR. FRANK LILLY, head of the Department of Genetics at the Albert Einstein College of Medicine in New York, is an expert on biomedical research. He is also an acknowledged homosexual and a founding member of the Gay Men's Health Crisis Center. On Thursday, President Reagan appointed him to the newly constituted Commission on the Human Immunodeficiency Virus Epidemic. The panel was created by executive order last month and will report in 90 days on the status of research on AIDS and the plans for addressing the epidemic in the future.

More than 40,000 Americans have already been diagnosed as having the disease, and more than half of these have already died. About three-fourths of those afflicted have been homosexual or bisexual men, and the gay community has been particularly supportive of AIDS victims, very successful in promoting education on the disease and admirably effective in prompting the government to mobilize resources in the effort. Because homosexuals have been both active and successful in the campaign against AIDS, it is wise to include at least one person from this group on the panel. This is not an entitlement or a quota that must be met; it is simply good sense. The White House has done well to name a man who is doubly qualified to serve -- not only because he is gay and can reflect the experience and concerns of that group but because he is a medical expert as well.

The panel is broadly representative and also includes New York's Cardinal John O'Connor. He is opposed on religious grounds to the practice of homosexuality, but he also leads a diocese in which the church has provided important services -- from hospital and hospice care to foster-care facilities for children -- to those, including homosexuals, who have AIDS. Retired Adm. James Watkins, who participated in the Defense Department's decision to test armed forces recruits for AIDS, brings another perspective. So does John Creeden, president of the Metropolitan Life Insurance Company, who has special knowledge of the economic costs and civil liberties problems connected with the disease.

The commission is not charged with studying homosexuality or making a judgment about it. Its task is to make recommendations about a deadly disease, and each of the 13 members will bring a special perspective and expertise to the study. The choice of Dr. Lilly makes clear the administration's decision to be inclusive in seeking advice and developing plans for the future. The commission would have been flawed from the start if the important homosexual group had been ignored.