Explain how the use of sequencing technologies finally brought the search for the HD gene to a close as reported by the Huntington's Disease Collaborative Research Group.

Sequencing of the contigs that covered the end of Chromosome 4 that had been previously identified as the location of the HD locus revealed an "interesting contig" that contained a CAG repeat sequence.The population of individuals without HD had 17 alleles with CAG repeats varying from 11 to 34 copies.HD individuals had alleles with 42-66 repeats of the CAG trinucleotide.HD was known to be a trinucleotide repeat disease and the research group proposed HTT as the gene responsible for HD and named its gene product huntingtin.