Dorothy McGuire, one-third of the 1950s show-stopping McGuire Sisters singing group, died Friday in Paradise Valley, Ariz., of Parkinson’s disease and age-related dementia. She was 84.

Her sisters Christine, 86, and Phyllis, 81, survive her.

The McGuire Sisters, known for their sweet harmonies, identical outfits and hairdos and synchronized body movements and gestures, earned six gold records for hits including 1954’s “Sincerely” and 1957’s “Sugartime,” both of which reached No. 1, 1954’s “Goodnite, Sweetheart, Goodnite” and 1955’s “Something’s Gotta Give.”

The sisters, who grew up in Miamisburg, Ohio, began performing in 1935 when Phyllis, the youngest, was 4. The got their big break on Arthur Godfrey’s Talent Scouts in 1952.

The McGuires made numerous appearances on TV variety shows hosted by Milton Berle, Andy Williams, Perry Como and others and toured into the late 1960s, making a last stop on The Ed Sullivan Show in 1968. They got back together in 1986 to tour nightclubs, and in 2004 they performed in a PBS special Magic Moments: Best of 50’s Pop.

The group performed for five presidents and Queen Elizabeth II of Great Britain.

Phyllis McGuire was involved with Las Vegas mobster Sam Giancana, a tale that was the subject of the 1995 HBO telefilm Sugartime that starred John Turturro as the Mafia boss, Mary-Louise Parker as Phyllis, Larissa Laskin as Dorothy and Deborah Duchene as Christine.

McGuire was married for 53 years to Lowell Williamson, a wealthy oilman. The couple had two sons, Rex and David. Survivors also include two stepchildren and nine grandchildren.

A memorial service is set for Sept. 15 at Valley Presbyterian Church in Paradise Valley.

The Associated Press contributed to this report.