People with an additional X or Y chromosome are at an increased risk of developing dangerous blood clots known as venous thromboembolism (VTE), according to a new study published in the Journal of the American Medical Association (JAMA). VTE is often fatal, and affects an estimated 9,00,000 people in the United States each year.
What is VTE?
It is a frequent complication for patients in intensive care and those with medical conditions such as cancer and Covid-19, and includes deep vein thrombosis and pulmonary embolism. Deep vein thrombosis refers to a blood clot in a deep vein, usually in the leg, and pulmonary embolism refers to a blood clot in the lung.
What is supernumerary sex chromosome aneuploidy?
The genetic condition of having an additional X or Y chromosome is known as supernumerary sex chromosome aneuploidy. Supernumerary is an adjective used to describe something present in excess of the normal or requisite number. Aneuploidy refers to the occurrence of one or more extra or missing chromosomes leading to an unbalanced chromosome complement.
How the study was conducted
The study, conducted by the Geisinger Health System, a regional healthcare provider headquartered in Danville, Pennsylvania, analysed genetic and electronic health record data on two groups of patients. A total of 6,42,544 patients enrolled in Geisinger’s MyCode Community Health Initiative and the UK Biobank. This is another large population study based in the United Kingdom. The MyCode Community Health Initiative is a precision medical project enrolling patients at Geisinger locations in Pennsylvania, and uses a system wide biobank to store blood and other samples for use in research, particularly genetic research.
What the study found
Approximately one in 500 Geisinger patients have an additional X or Y chromosome in their genome network beyond the typical two X chromosomes found in females, and X and Y chromosomes found in males, the authors found.
People with supernumerary sex chromosome aneuploidy were at increased risk for VTE
People with an additional X or Y chromosome had a risk for VTE that was four to five times higher than expected, the study said.
In a statement released by Geisinger Health System, Dr Matthew Oetjens, the lead researcher, said an additional X or Y chromosome is more common than many people think, but it does not often receive clinical attention. He added that the study shows that there are underappreciated health risks associated with these disorders that could change medical care if known in advance.
Alex Berry, the first author on the paper, said VTE is a life-threatening, but preventable disease, and it is important to identify individuals at high risk for VTE to minimise unnecessary illness and death.
Is the loss of an X or Y chromosome linked with higher risk of blood clots?
The loss of an X or Y chromosome, known as Turner syndrome, is not associated with a higher risk of blood clots, the analysis suggested. The authors concluded that further research is needed to understand the medical implications of this association.