Sandra Layne is accused of shooting grandson Jonathan Hoffman eight times Friday after an argument inside her West Bloomfield home.
He called 911 to say he had been shot.
He was taken to a nearby hospital but was dead upon arrival.
No bond was set for Layne after she was arraigned on Monday.
She is held at the Oakland County Jail and is scheduled to appear in court Thursday for a preliminary examination.
Hoffman had been living with his grandparents so he could stay in Farmington schools while his divorced parents settled in Arizona, said his father, Michael Hoffman, of Scottsdale, Arizona.
Jerome Sabbota, a lawyer for the grandmother, said Jonathan Hoffman had legal problems over drugs and had conflicts with his grandmother.
Sabbota said his client fired her new .40-caliber semiautomatic handgun because she felt she had no choice.
"This is a 74-year-old lady who just bought a gun. It's not like she was a pro. I don't think she was in control of her emotions. She was afraid. She's not a big, strong woman," Sabbota said.
Regardless of what difficulties the teen gave his grandmother, there was no reason for her to shoot him, his father said.
"I'm not saying he was aggressive, but if he was, I don't understand how being aggressive but unarmed would justify her using deadly force," Michael Hoffman said.
Police were called to the home in March for a dispute between Layne and her grandson.
According to police, Jonathan Hoffman was in the street screaming and was out of control.
No charges were filed.