What is TK2d?
TK2d, or thymidine kinase 2 deficiency, is an ultra-rare primary mitochondrial myopathy that causes progressive muscle weakness associated with debilitating and life-threatening symptoms, including, difficulty breathing, limited mobility, and challenges eating and swallowing.
A factsheet was created in partnership with the TK2d community that can be found here:
Due to the complexity, progressive nature and the wide range of symptoms TK2d can cause a multi-disciplinary health team is needed to manage the care of patients.
Who does it affect?
TK2d is a mitochondrial DNA deletion/depletion syndrome that affects children and adults and is confirmed by genetic testing.
Today the exact number of people with TK2d is unknown. In 2018, there were about 107 individuals reported in the medical literature with this condition.* Because TK2d was first described in 2001 and is not a well-known cause of muscle weakness, it is likely that TK2d is underdiagnosed. Other myopathies that look like TK2d include Pompe, Limb Girdle Muscular Dystrophy, Kearns Sayre Syndrome (KSS), and CPEO.
*For the original source of this information, click here.
What is the treatment?
There is no approved therapy for TK2d and treatment is mostly supportive to manage symptoms.
This typically involves a team of specialists including a geneticist, neurologist or neuromuscular specialist, pulmonologist, and physical and occupational therapists. Some patients may use a wheelchair for mobility. In addition, many people with TK2d need BiPAP, CPAP, or a ventilator to help them breathe.
An investigational nucleoside therapy is being evaluated for people with TK2d in a clinical trial.
Genetic counselling is recommended for individuals with TK2d and their families.
Where can I get more information?
There are a number of excellent sources of information available on Orphanet and our member websites:
TK2d Awareness day
In 2022, together with our partners, we launched the first world TK2d Awareness Day. The purpose of this day is to raise awareness of this rare but debilitating disease. The day forms part of the calendar of events included in World Mitochondrial Disease Week, and falls on the second Tuesday of September every year.
TK2d Awareness Day will be on 10 September 2024
For more information visit Mitochondrial Disease Week.
Rare but worth the share
TK2d has only been recently characterised, so its rate of occurrence is unknown. Being a rare disease, the symptoms are often misdiagnosed. To increase awareness of the symptoms of TK2dD, IMP collaborated with UCB (formally Zogenix) to produce an infographic which we call ‘Rare but worth the share’. We’d love for you to use this and share it on your platforms.
Download the 'Life with TK2d' infographic
