Elevated levels of cardiac troponin I (cTnI) in serum are more common and severe in patients with Duchenne muscular dystrophy (DMD), according to a new study published in Muscle and Nerve.

“cTnI elevation preceding cardiac dysfunction may represent an early phase of cardiomyopathy progression and may be a biomarker for early detection of cardiomyopathy in these dystrophinopathies,” the researchers wrote.

cTnI belongs to the troponin complex and is a major component of myofibrils, which is uniquely expressed in the heart muscles. Following heart injury, cTnI is present in the blood making it a potential marker for both myocardial infarction and chronic heart conditions. However, there is little information about its diagnostic value in patients with DMD and Becker muscular dystrophy (BMD).


Continue Reading

It has also been reported recently that the ACTN3 XX genotype, which consists of a homozygous premature stop codon in the ACTN3 gene encoding alpha-actinin-3, is associated with a lower left ventricular dilation-free survival rate in patients with DMD.

The present study demonstrated that the ACTN3 XX genotype may be a risk factor for early myocardial injury and contribute to cTnI serum levels.

Read more about DMD risk factors

The team led by Kazumoto Iijima, MD, PhD, director of the Hyogo Prefectural Kobe Children’s Hospital in Japan retrospectively analyzed the serum levels of cTnI from 127 patients with DMD and 47 patients with BMD. They also assessed the relationship between levels of cTnI and echocardiography data as well as the ACTN3 XX genotype.

The results showed that the levels of cTnI were significantly higher among patients with DMD compared to patients with BMD. The proportion of patients with DMD with abnormal levels of serum cTnI was also higher compared to patients with BMD, which was especially the case for patients in their 20s.

In patients with DMD, the levels of serum cTnI reached a maximum at age 13 years, which was followed by an abnormal left ventricular ejection fraction the year after. In patients with BMD, maximum levels were reached at age 14 years, and left ventricular ejection fraction became abnormal after 3 years. In patients with DMD who had the ACTN3 XX genotype, cTnI levels were significantly elevated and became elevated significantly earlier.

Reference

Yamaguchi H, Awano H, Yamamoto T, Nambu Y, Iijima K. Serum cardiac troponin I is a candidate biomarker for cardiomyopathy in Duchenne and Becker muscular dystrophies. Muscle Nerve. Published online February 16, 2022. doi:10.1002/mus.27522