A new retrospective study of a group of patients with thymidine kinase 2 deficiency (TK2d) offers real-world insights into this ultra-rare mitochondrial disease’s progression and healthcare burden. Results from the study will be presented at the 2026 Muscular Dystrophy Association (MDA) Clinical & Scientific Conference in Orlando, Florida, March 8 to 11, 2026.
“This study provides critical insights into the clinical course of TK2d and associated healthcare burden in a pediatric cohort. These descriptive findings contribute to the limited literature, underscoring the need for early diagnosis, proactive patient management, and multidisciplinary care,” said the study’s authors.
The authors aimed to describe the clinical disease course in a group of patients with TK2d, including age at symptom onset, diagnosis, motor milestone loss, need for ventilatory and feeding support, and the associated healthcare burden, such as utilization of outpatient visits, hospitalizations and specialist care.
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The methods consisted of a retrospective examination of de-identified electronic medical records from six patients with TK2d at Rady Children’s Hospital San Diego. The group included three male patients and three female patients; all were Hispanic/Latino.
The authors found that the mean age when symptoms started was 3.6 years, ranging from 1.9 to 8.8 years. The average age when patients were diagnosed with TK2d was 16.1 years, ranging from 7.7 years old to 23.7.
The authors found that patients had a high number of outpatient visits. They averaged 91.3 visits annually, across specialties like neurology, pulmonology and sleep medicine.
The patients became wheelchair users at a mean age of 7 years, and started using a ventilator by 11.1 years. Patients were first hospitalized at a mean of 9.5 years. All the patients were alive at the last follow-up.
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