Final answer:
The gene responsible for Huntington's disease was discovered in 1993 and is located on chromosome 4. This finding built on the foundational work in genetics, including the chromosome maps developed in the early 20th century.
Step-by-step explanation:
The chromosomal location of the Huntington disease gene was first discovered in 1993. It is located on chromosome 4. Huntington's disease is caused by an abnormal dominant allele for the Huntington gene, resulting in nuclear inclusions characteristic of the disease in neuron cells. Notably, this discovery was made nearly 80 years after Alfred Sturtevant created the first chromosome map in 1913, a linear representation of gene order and relative distance on a chromosome as part of Thomas Hunt Morgan's laboratory work, which helped lay the foundations for understanding genetic locations and their linkage with genetic disorders.