ST. LOUIS -- The older daughter mastered the intricacies of the square root at the age of 6. Now a freshman at one of the country's top engineering schools, she is a member of Mensa International, the organization limited to those with an IQ in the upper 2 percent of the world's population.

Her sister, a junior at a county high school, defies even greater odds.

She is one of the rare people on the planet who have been diagnosed with the genetic aberration identified in scientific circles as the "interstitial deletion of the short arm of chromosome 1."

The axis formed by sisters Sara and Molly Cantonwine extends far beyond the south St. Louis County subdivision they call home, transcending family to inform the education of the 30,000 children under the supervision of their mother, the superintendent of the St. Louis Public Schools.

When it comes to describing her children, Diana Bourisaw is disarmingly direct.

Sara, a first-year double-major at the Illinois Institute of Technology in Chicago, is "gifted and talented."

Molly, 16, is not. At least not as the term is generally defined.

They are two daughters at two extremes, each with gifts that reach into the lives touched by their mother and father, lawyer Steven Cantonwine.

"They say there is a reason parents of special-needs kids are given a challenge," Bourisaw said.

Appreciating strengths

For Bourisaw and Cantonwine, the reasons are abundantly clear.

At school district headquarters, Bourisaw said, her children "help me appreciate the strengths of all kids. Some parents think the only way to excel is academically, to earn a place on the Honor Society or a spot in a top college. Sara excels at academics. But Molly excels in other ways. She excels by serving [Mass] at church and helping our neighbors and volunteering."

The intersection of Bourisaw's personal and professional lives rarely displays itself in public. During the first stormy year of her tenure atop the state's largest school district, she remained serene in the face of barbs from the former School Board president, tension over state intervention and the transition to the appointed board now running the schools.

It's in conversations with reporters or addresses to small audiences that Bourisaw's passion for education, and a glimpse at the forces behind it, emerge.

Parenthetically, Bourisaw does occasionally reveal that her children have special needs, each in her own way.

Sara, as a college freshman, is moving in her own direction now.

Molly, meanwhile, is nurtured by a network that moves from home into the neighborhood, her school, church, advocacy groups for the disabled and other organizations that support those efforts.

Special needs

Molly's differences, Cantonwine and Bourisaw say, were obvious almost from the start. Her parents waited nine months for her sit up; 14 months passed before she slept through the night.

Until geneticists identified her disorder in 2001, the source of wide-ranging neurological symptoms that veered from attention deficit hyperactivity disorder to obsessive-compulsive disorder to emotional withdrawal remained a mystery. The disorder is marked by a mutated chromosome, which leads to a host of cognitive problems.

Not programmed to equate darkness with rest, Molly often wanders the house most of the night, able to subsist on sleep of two hours or less. Naturally gregarious, she withdraws when teased or criticized. Her attention span is short, but not so much that she can't read, write or understand basic mathematics.

The observations of Bourisaw the parent provided incomparable lessons for Bourisaw the administrator.

In hiring for the city schools (and, before that, the Fox School District and as an area superintendent in Sacramento, Calif.), Bourisaw's gold standard is the teacher who showed Sara how to capitalize on her intelligence and, when Sara's sister entered her class years later, tapped into every avenue of Molly's capabilities.

"That teacher knew how to adapt to the needs of the kids in her class. And that's what I want for our kids," said Bourisaw. "I want to create schools that are supportive of all kids; schools that challenge the gifted child and also challenge the special-needs child."