Graduate student Dee Innay works in a human genome lab, whose goal is to identify the human gene responsible for a form of muscular dystrophy (MD).  Dee has mapped the MD gene to a narrow interval of chromosome 9.  The DNA sequence from that interval contains 6 ORFs. 

The lab works with 4 different extended families in which MD is segregating and has genomic DNA samples from 35 family members that are either affected, unaffected carriers, or unaffected non-carriers.  How would Dee figure out which ORF corresponds to the MD gene?  (Working in humans, she cannot perform transformation rescue or use a test that relies on gene function or rescue of the mutant phenotype.)