When an Israeli doctor advised Ruth Langotsky in 1974 to institutionalize her 2-year-old autistic son because there was not medical treatment for his disorder, she was devastated.

Ruth says she realized she could never place her child in an institution.

She and her husband left Israel in 1976, determined to find U.S. physicians and teachers who could help unlock the mysterious and silent world in which their son Avner lived.

After three years in the Washington area, the Langotskys returned to their home near Tel Aviv last week. They took with them pledges of financial support from U.S. friends and philanthropic agencies to expand a small school for autistic children near Tel Aviv. They hope more financial help will follow them.

Two years ago, Ruth, with the help of Leah Rabin, wife of former Israeli Prime Minister Yitzhak Rabin, raised funds to sent two American teachers experienced in working with autistic children to organize the school.

Although it has space for only 10 autistic children, the shcool has become so well known that 210 afflicted youngesters now wait to enter.

Ruth said she is determined to find enough money both for the school in Tel Aviv and for a farm community in Israel where autistic young adults could live and receive vocational training.

She said she wants to spare other parents of autistic children the horror she and her husband endured when an Israeli neurologist labeled their son "retarded and autistic" and advised them to place him in an institution. The doctor told her, she said, that "You're young -- you'll have another child."

But to Ruth and Joseph, Avener was "our prince." Joseph had a son and daughter by a previous marriage when he met Ruth, a widow with a 4-year-old son. The couple was married in 1971 and Avner was born July 4, 1972.

"We were sure he would bring joy and happiness to all of us," Ruth said.

It was Joseph who first became concerned about Avner's curious behavior, she said, adding that "I was so crazy about him i was the last one to see something was wrong."

Avner had shown great intelligence as an infant, his mother recalled proudly. "He could take a key and put it int a lock when he was just a year old. He toilet trained himself at 2."

But soon his abilites were overshadowed by his strange behavior, she recalled. He would stiffen as if he were blind, she said. And without provaction, he would scream or els remain mysteriously silent.

Through a neighbor, Ruth heard about a Philadelphia educator, Dr. Carl H. Delacato, who in 1974 published abook a out autistic children entitled "The Ultimate Stranger, The Autistic Child."

The Langotskys were told that Delacato traveled to Israel three times yearly to visit a clinic he maintains there to teach parents and educators how to work with autistic children and those with autistic children and those with severe behavioral problems. But consulting with him would be nearly impossible, friends had told them. Desperate to find help, they decided to go to the United States to find Delacato and other doctors who might offer them guidance.

"We decided to make a concentrated effort to try and find help," Joseph said, "We had to seek out all the possibilities so we could make up our minds what to do next."

In Philadelphia the Langotskys spoke with Delacato, who "told us to read his book and write a report about our child based on what we read." Ruth said. After reading Delacato's book, she said, "For the first time I understood Avner. The book hust deciphered my child."

Delacato, a pioneer in the field of autism, maintains that autistic children have mild brain damage that affects their sensory abilities. In his clinics, he teaches parents and educators how to work with autistic children to "normalize their senses."

When the educator saw Avner During a trip to Israel a few weeks after the Langotskys' trip to the United States, he confirmed the diagnosis that the child is autistic.

Delacato said Avner7s hearing could be likened to that of a dog, who can hear noises unaudible to humans. He would scream, Delacato explained, to neutralize the intolerable cacophony audible only to him. Avner was afraid of stairs because his eyes often perceived objects on two planes, drawing for the youngster a visual nightmare, and he rejected his mother's tough, because to Avner the loving caresses felt like a hot iron scorching the skin, the educator said.

While Delacator's explanations were devastating to the Langotskys, he offered them what no one else had: hope. Ruth was given exercises to do with Avner to help him tolerate touch and sounds. Ear plungs were placed in Avner's ears and for the first time, Ruth said, "he tolerated our talking to him." For a long time the Langotskys lived in a silent world too because they knew the sound of their voices disturbed the youngster.

Joseph, who had reenlisted in the Army in 1968, was assigned a position as assistant military attache at the isreli embassy in Washington. N the United States, Avner was enrolled in the School for Contemporary Education in Alexandria and then Christ Church Child Center in Bethesda. Avner and Ruth traveled to the Judevine Center in Missouri, where autistic children receive intensive training.

"I came with a child I had no eye contact with," Ruth recalled. "He was beautiful but very far away." They will return to Israel with a far Differnet youngster, she said proudly.

Delacato, who periodically examines Avner, said the youngster's chances for reaching normalcy, as defined by Delacato, is being able to care for oneself, earn a living and have a close relationship wth a member of the opposite sex. In Israel, he said, being able to serve in the military is an added criteria. "I feel Avner has a good chance to meet that too."

The Langotskys and Delacato are conviced that Avner's ability and desire to speak will increase as he continues to progress. How he occasionally utter one or two words.

Avner, who was 7 on July 4, "has changed our life. But he has child like Avner makes your whole life richer. Do you know the most beautiful present Avner could bring me? Some day I'll be in the kitchen and Avner will call to me -- he'll call me Ima, the Hebrew word for Mother." CAPTION: Picture, Ruth Langotsky says son Avner has "enriched our lives." By Craig Herndon -- The Washington Post