A mutated CFTR gene codes for an abnormal CFTR protein. This protein alters the normal function of the cell, leading to the disorder cystic fibrosis. Based on the statements, which of the following is true?

Cystic fibrosis is caused by a mutated CFTR gene.

The CFTR gene always causes cystic fibrosis.

Cystic fibrosis causes mutations to the CFTR gene.

Cystic fibrosis is an autosomal dominant disorder.