Douglas and Betsy Astolfi, the parents of a strapping boy of 10 and a vibrant 5-year-old girl, hoped their next child would also be the picture of health. But when Katherine was born last March 27, the Astolfis, of Johnstown, Pa., discovered their new infant daughter had 38 fractured bones.

Her ribs were broken in 24 places. A thigh bone and a leg bone were broken. And she had fractures in a collar bone and jaw bone.

The fractures, which occurred during development in the mother's womb and during the delivery process, are the result of a genetic disorder called osteogenesis imperfecta, or "brittle bone disease."

My initial reaction was complete shock and numbness." said Astolfi dean ofcontinuing education at the University of Pittsburgh atJohnstown. "We had expected a completely normal baoy. But after the X-rays, doctors told us the baby had a classic textbook case of O.I."

Katherine Astolfi's 38 fractures have now healed and she has no further breaks. The Astolfis have learned to take special care in how they handle the child.

When we last brought her home, we lived in absolute fear that everytime we picked her up we would hear a bone snap." said Mrs. Astolfi. She said that the baby sleeps on a floatation mattress to fully cushion her body.

According to the Osteogenesis Imperfecta Foundation, about one out of every 50,000 babies born each year in the United States has osteogenesis imperfecta generally translated as imperfect bones from birth."

Currently, between 10,000 and 30,000 Americans are affected by the disease which leads to repeated broken bones because of the poor quality of bone tissue. A victim of O. I. can have anywhere from eight to 700 bone fractures from birth to age 60, according to the foundation.

Persons with O. I. often have a blue discoloration of the whites of the eyes, poorly formed teeth and mal-functioning joints. The disease can be cur as a genetic mutation or it can be inherited from a previous generation.

Some victims of O. I. can lead normal lives with few fractures or signs of bone deformity. But in worse cases repeated bone fractures eventually lead to groteque detormities.

Despite its sometimes debilitating effects on its victims, the "brittle bone disease" remains a little known ailment among the general population. Doctors often do not properly diagnose it in infants. And society at large is generally not prepared to accommodate the person with O. I. complications.

A group of adult O. I. patients, doctors, researchers and parents with their "birttle bone" children met recently in a symposium at Children's Hospital here to review the problems of the disease and to seek ways of obtaining more money for research into its causes and cure.

A spokeman for the National Institute of Arthritis, Metabolism and Digestive Diseases said 14 researchers at medical centers across the country currently share more than $300,000 in federal rants for the direct study of O. I. He said additional federal dollars go into indirect studies of O.L, as it relates to similar diseases.

But Roberta DeVito, chairman of the newly formed American Brittle Bone Society in Cinnaminson, N.J., and mother of a young O.I. child, said that the amount of money now spent on finding a cure for brittle bone disease is not nearly enough. She and others recently spent a day on Capitol Hill lobbying for more funds.

Although there have been some experiments with the chemical treatment of O.I. using the hormonal drug, Calcition, to strengthen fragile bones, the most successful treatment of the disease has been surgical management.

In a procedure called "rodding," doctors thread small steel rods into the long bones of the O.I. victims to help straighten and strengthen bones that have fractured or break easily.

Rodding was unheard of 55 years ago when Margaret Cauffield was born with O.I. in western Pennsylvania.She had no fractures until she tripped on a rug at age two and broke a thigh bone.

"My parents took me to the doctor and he told them that with the disease I wouldn't live past puberty." Miss Cauffield recalled. "He told them to take me home, put me out in the sun on a sand pile and let me just play until my time came."

As a result of the doctor's prognosis, Miss Cauffield said her parents, who expected her to die any day, made no effort to help her get a formal education.

Miss Cauffield, who is wheelchair bound, said she was 34 years old before she began to receive formal training atenter in Fishersville, Va.

From her vocational training,she was hired by the federal Office of Vocational Rehabilitation as a grade three clerk typist. Now she is a grade six administrative clerk.