A Texas high school student growing out his hair to make a wig for his sick younger sister said he was threatened with suspension over the length of his hair.

Alan Johnson said his 11-year-old daughter Maggie was diagnosed in October with an autoimmune disease affecting her kidneys. As a result of her treatment, which according to her father has included chemotherapy, some of her long curly hair has fallen out, which prompted her brother, Newt Johnson, 16, to grow out his hair to make a wig for her.

Last month, the Friday before Martin Luther King Jr. Day, Alan Johnson said his son, whose hair is now about 4 to 6 inches long, was told by his principal at Poth High School that he would have to cut his hair or he couldn't return to school. The Poth Independent School District's student handbook states "male students’ hair shall not extend beyond the ear opening on the sides nor beyond the top of a dress shirt collar in the back."

The principal was aware Newt Johnson was growing out his hair for his sister, Alan Johnson told NBC News on Monday.

When Newt Johnson returned to school after the holiday, administrators contacted his mother, Jamie Mathis-Johnson, who was told she needed to pick him up because his hair was not cut. When she arrived, she spoke with the principal and questioned whether her son was being kicked out of school, Alan Johnson said.

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"He said, 'No, he can come back when he gets his hair cut,'" the father said. "They made him leave, they knew he wasn't going to get his haircut."

But the school district claims the family chose not to challenge the dress code, saying in a statement Friday its "integrity and board approved policies are being maligned and twisted on social media."

"There was an avenue and process to seek resolution to the issue that the parent chose not to take, thereby negating the opportunity for a different resolution," the statement signed by Superintendent Paula Renken said.

Left out from local media reports was the amount of money that has been raised for the Johnson family, the superintendent said in the statement, while also expressing support for the handling of the matter by Principal Todd Deaver and the enforcement of the district's "conservative dress code."

"Principal Deaver performed his duties as he is expected to under the policies and procedures in place," Renken said.

Alan Johnson said he and his wife were never offered a conversation with the superintendent and that he only withdrew his son from the school after the teen was reported to a truancy officer. Newt Johnson is now being home-schooled.

Alan Johnson said he is proud of the stance his son has taken.

"If he's got his mind made up and that's what he believes then that's what he can do," Alan Johnson said. "I'm proud of him ... it's disappointing it's come to this. No one wants something like this to happen. But he loves his sister so much, he's made up his mind he's going to help her."

Another Texas teen, De’Andre Arnold, attracted national attention when he said he had been suspended and told he could not walk at graduation if he did not cut his dreadlocks to meet his school district's dress code. Arnold, who is black and has worn dreads since seventh grade, recently withdrew from Barbers Hill High School in Mont Belvieu, in southeast Texas.

Alan Johnson said he is aware of Arnold's situation and that he feels it is similar to his son's.

"How are you going to tell a young man he can't have long hair?" he said. "I think school districts have a lot of other issues that are way more pressing than how a young man wears his hair."