Discovery in Venezuela
David Ochoa
A health professional assists a patient during a medical visit in San Luis, Maracaibo, by the nongovernmental organization Primeros Auxilios LUZ.
Some 8 hours by car from Barranquilla sits Lake Maracaibo, Venezuela, home to the largest known clusters of HD patients worldwide. The disease is believed to have come to the shores of Lake Maracaibo with a lone European immigrant – a Spanish sailor, many claim – at the end of the 18th century. Cases were first described in the 1950s by a young Venezuelan physician named Américo Negrette, MD.
Dr. Negrette’s findings were ignored by health officials in Venezuela and went unnoticed in the international research community until 1972, when a student of Dr. Negrette’s presented at an HD conference in Ohio. There he drew the attention of the American neuropsychologist Nancy S. Wexler, PhD. Dr. Wexler’s own mother had died of HD, and her father Milton, a noted psychoanalyst, founded the first research foundation dedicated to the disease.
David Ochoa
Patients wait in line to be seen during a medical visit in San Luis, Maracaibo, by the nongovernmental organization Primeros Auxilios LUZ.
While prevalence of HD in North America, Australia, and Europe is about 1 in 10,000, the region around Lake Maracaibo saw 70 times that rate at the time, thanks to high birth rates, geographic isolation, and extensive intermarriage within a handful of families. The families comprised mostly poor fishermen who lived in makeshift homes in towns ringing the lake.
In 1979, Dr. Wexler, with funding from the U.S. National Institutes of Health, began making annual research visits to Lake Maracaibo, and in 1983, the research group she coordinated, using data from blood and tissue samples donated by affected families, identified the location of the huntingtin gene on chromosome 4 (Nature. 1983 Nov 17;306[5940]:234-8). A decade later, the researchers isolated the mutant version of the gene and found it to be a triplet (CAG) expansion mutation, with more CAG repetitions associated with earlier age at disease onset (Cell. 1993 Mar 26;72[6]:971-83). Dr. Wexler and her colleagues’ findings led to the first genetic tests for HD.
David Ochoa
A health care worker takes vital signs from a patient during a medical visit in San Luis, Maracaibo, by the nongovernmental organization Primeros Auxilios LUZ.
Nationalist policies in Venezuela ended Dr. Wexler and her colleagues’ annual visits to Lake Maracaibo in 2002, along with the food, clothing, and medicines that the group routinely distributed to the families when they came.
Over 23 years, the researchers obtained data from some 18,000 individuals, but the families did not benefit in any durable way from the research. Local investigators with whom Dr. Wexler’s group collaborated lacked the resources and training to continue independently.
Access to medications is limited in Venezuela, and there is no institutional support for hundreds of HD patients living in extreme poverty, many of them descendants of the patients who contributed to the research and generation of these samples. The families’ biological material was sent to labs abroad, where investigators continue to derive findings from it today. Though genetic testing was performed on thousands at risk for the disease, few received access to their results through genetic counseling. A hospice established by Dr. Wexler’s foundation limped along until 2014, when it was finally shuttered.