Objectives:
Heritable disorders of connective tissue (HDCT) are associated with morphological and functional disorders of different organs and systems. The aim of our study was to determine the clinical signs of heritable disorders of connective tissue and oxyproline levels in children with acute rheumatic fever (ARF) and rheumatic heart disease (RHD).

Material and methods:
A total of 155 patients aged 4 to 17 years participated in the study: 23 with ARF, 78 with RHD, and 54 healthy patients with a history of ARF. All patients underwent a standardized examination protocol, which consisted of a detailed medical history recorded by the physician, general and special laboratory tests, electrocardiogram, echocardiography, and Doppler echocardiography. Special attention was paid to the clinical signs of HDCT. The intensity of the metabolic processes in the connective tissue was evaluated by serum oxyproline levels.

Results:
The signs of HDCT were revealed in 121 (78.1%) of the patients with ARF and RHD. Among cardiovascular manifestations, we observed mitral valve prolapse most often – in 91 (58.7%) patients. Musculoskeletal anomalies were observed in 94 (60.7%) patients. Both groups of patients with ARF and RHD had elevated mean serum oxyproline levels.

Conclusions:
Children with acute rheumatic fever and rheumatic heart disease presented with a number of signs characteristic of heritable connective tissue disorders. The cardiovascular and musculoskeletal system changes are the most frequent among all features of HDCT. Elevated levels of serum oxyproline in patients with ARF and RHD confirm connective tissue disorders. Children with manifestations of HDCT are at the risk of ARF and RHD development.