The unusually high prevalence that has been noted in Tasmania has prompted researchers to conduct a variety of studies regarding the region’s Huntington’s Disease population, making it a well-studied and important area in the context of global Huntington’s Disease.
In 1949, Dr Charles Brothers came across a large Tasmanian family that was presenting symptoms of Huntington’s Disease. This family has continued to be studied over the years, but for medical confidentiality purposes, they are known in research literature only as The Brothers family.
It is believed that an English woman identified as Mary first brought Huntington’s Disease to Tasmania in 1842. Mary was born in Long Sutton, Somerset, England in 1806, and appears to have inherited the disease from her father, Robert, who was born in 1776 in Somerset. Researchers have named Robert the originator of Huntington’s Disease in Tasmania, and he is considered to be the first generation of the Brothers family.
Mary married several times before leaving England for Launceston, Tasmania with her husband, Charles, and her seven children in 1842. Mary proceeded to give birth to seven more children in Tasmania. Of her 14 children, nine developed Huntington’s Disease. All nine children later went on to have children of their own. As of 1990, seven of these nine lineages still had living descendants, with six branches containing descendants that were either at risk or affected by Huntington’s Disease.
Nine generations of the Brothers family have been studied, and more than a century after Mary’s death, there have been 765 identified family members living at risk. The average age of onset for affected Brothers family members was found to be 48.6 years old, and the average age of death was 61.8 years. Fertility studies showed that there was no evidence that suggests that the ability to reproduce was negatively impacted in any of the affected individuals. In fact, the disease appeared to correlate with greater fertility amongst Brothers family members.
Studying the Brothers family lineage provided researchers with a better understanding of Huntington’s Disease and helped explain the higher than expected prevalence of Huntington’s Disease in Tasmania by allowing them to trace the disease back to a single common ancestor.
The fact that Tasmanians with Huntington’s Disease can be traced back to a common ancestor appears to explain the higher than expected prevalence of Huntington’s disease in Tasmania.