CAPITAL REGION — Today is leap day, a blip that appears on the Gregorian calendar once every four years and is generally ignored by the vast majority of people.

But for a special few, the so-called “29ers,” Feb. 29th is the day to celebrate a birthday that comes once every four years. February has only 28 days during regular years, the shortest month on the calendar.

Ann Comley and Matthew Knuth of Glenville are members of the 29ers club. The membership consists of approximately 200,000 people in the United States and 4 million around the world, according to leapyearday.com.

Comley, principal of Lincoln Elementary School in Scotia, is 52 in actual years, but 13 in leap years. Knuth, a second-grader at the school, is 8 today, but is “technically only 2” in leap years, he said.

Comley said being a leap year baby hasn’t changed her life one bit. She has never had her license rejected or questioned because it lists Feb. 29 as her birthday, a complaint common to some 29ers. And she never had anyone question the odd date when writing out a check.

However, the children at her school get a kick out of her unusual birthday date.

The school’s older children “can figure out how old I am” when she tells them she celebrates her birthday every four years, while “the younger children say it’s not fair that I only get a birthday once every four years,” Comley said with a laugh.

When she was younger and it wasn’t a leap year, Comley would celebrate her birthday Feb. 28. She now celebrates it March 1. “My parents chose Feb. 28 when I was younger,” she said.

Her friends and family are planning special events today to help her celebrate her “13th birthday,” she said.

Knuth, meanwhile, enjoys being a leap year baby. “It’s really good,” he said. He has known for years he celebrates a birthday unlike those of other children. His schoolmates also know this and they plan to help him celebrate today. Comley, who calls Knuth is her birthday buddy, will help him celebrate.

Pope Gregory XIII added leap day to the calendar in 1582. He did so out of concern that one day Easter and Christmas would coincide without his intervention, according to leapyearbaby.com.

Gregory determined leap day should fall on any year divisible by four but not 100, except when the year is divisible by 400. Century years were made leap years if they were divisible by 400.

At the same time, Gregory made the end of the year Dec. 31, moving it back two months so Easter would occur in the spring, according to the Web site.