27P Muscle ultrasound findings in paediatric patients with TTN gene related congenital myopathy

• Published in: Neuromuscular disorders : NMD 2024-10, Vol.43, p.104441, Article 104441.225
• Main Authors: Sarkozy, A., Perry, L., Cicala, G., Manzur, A., Vanegas, M., Khries, M., Sudhakar, S., Clark, C., Muntoni, F., Jungbluth, H., Baranello, G.
• Format: Article
• Language: English
• ISSN: 0960-8966
• DOI: 10.1016/j.nmd.2024.07.234

Biallelic pathogenic TTN gene variants cause a form of congenital myopathy (TTN-CM) with mostly neonatal/paediatric onset. Natural history and markers of disease progression are not fully known. A natural history study for TTN-CM has been initiated at Great Ormond Street and Evelina Children's Hospitals (London, UK) in January 2024. One of its scopes is to investigate the role of muscle ultrasound (US) imaging as disease biomarker to aid diagnosis and monitor progression. For this, US will be performed on rectus femoris, vasti, sartorius, biceps femoris, semitendinosus, semimembranosus, tibialis anterior, extensor digitorum longus (EDL), peroneus, soleus, medial and lateral gastrocnemius muscles in the lower limbs, and deltoid, biceps and triceps muscles in the upper arms, at baseline and 12-month visit. Here we present results of baseline US for 6 of 7 patients (age range 3-16 years; 3 females, 3 males) recruited so far. One patient did not have US due to external factors. Experienced raters graded available imaging using the modified Heckmatt scale. Analysis of US images showed variable, but consistent involvement of semitendinosus and semimembranosus muscles in all 6 patients (Heckmatt grade 2-3). Five patients showed sparing of biceps femoris. Mild involvement of lower leg anterior compartment muscles was also noted, with comparative sparing of EDL in 2 patients. Involvement of upper leg anterior, and lower leg posterior compartments was milder and variable. Triceps showed increased echogenicity in 3 patients. Results of further 10 patients, planned to be recruited by August 2024, and comparison with MRI, will also be presented. This preliminary data confirms feasibility of US in TTN-CM patients and highlights its role as a non-invasive diagnostic tool to provide imaging biomarkers. This is particularly helpful in younger patients, where muscle MRI may not always be possible, and to further support validation of unclear genetic findings.