Connie Winslow is deaf. When she was old enough to
attend school, she began having fainting spells, which her teachers
and parents noticed happened when she became excited. One Christmas
she was so thrilled with her gifts, that she promptly fainted. Her
parents took her to the emergency room, where doctors assured them,
as they had in the past, that there wasn’t a problem. The spells
continued and Connie became able to predict the attacks, telling
her parents that her head hurt before the spells

Her parents took her to a neurologist, who checked
Connie’s heart and diagnosed Long Q-T syndrome with deafness. This
condition was also known as Lange-Nielsen syndrome.

The physician explained that this is a severe form of
long-QT syndrome, which is an inherited heartbeat irregularity that
can be fatal. Seven genes can cause long Q-T syndrome. The
Winslows

(parents) visited a medical geneticist, who discovered
that each had a mild, heartbeat irregularity that did not produce
symptoms. Connie’s parents also had normal hearing. Connie’s
younger brother Jim was also hearing-impaired and suffered night
terrors, but had so far not fainted during the day.
  After a more complete examination and genetic testing
the doctors realized that he had the full syndrome. A younger
sister, Tina, was still a baby, and was tested. She did not have
either form of the family’s illness; her heartbeat was
normal.

Connie and Jim were treated with Beta-blocker drugs, and
each has a Pacemaker to regulate heartbeat. Connie may receive an
implantable defibrillator to automatically correct her heartbeat
when it veered out of control. Diagnosing Connie may have saved her
brother Jim’s life.

7a. Which Exceptions and Extensions of Mendelian
Inheritance are related to this syndrome?

7b. Why did Tina not inherit the symptomatic or
asymptomatic form of the disease?