Received: June 18, 2026
Accepted for publication: July 24, 2026
Published online: September 30, 2026
UDC: 616.24-008.4-056.7
DOI: 10.26212/2227-1937.2026.38.86.007
RESPIRATORY DISORDERS IN PATIENTS WITH MUCOPOLYSACCHARIDOSIS TYPE VI BASED ON SPIROMETRY FINDINGS
Tulebayeva А.К1, Sharipova М.N2, Nurkhanova А.Т2,
Nurmagambetova B.A2, Kurmanbekova S.K1.
1 NCJSC «Asfendiyarov Kazakh National Medical University»,
2JSC «Scientific centre of paediatrics and paediatric surgery» Almaty, Kazakhstan
Introduction: Mucopolysaccharidosis (MPS) is a rare genetic lysosomal storage disorder of connective tissue. The main cause of the disease is the absence or deficiency of a specific lysosomal enzyme, that is responsible for the breakdown of glycosaminoglycans (GAGs). Currently, it is known 8 types of MPS: I, II, III, IV, VI, VII, IX, and X. Pathological mutations in the ARSB gene cause lack of activity of lysosomal enzyme – arylsulfatase-B, that breaks up GAGs such as dermatan and chondroitin sulfate. Deficient arylsulfatase-B leads to aggressive accumulation of undegraded GAGs in connective tissue of all organs, causing multiorgan damage and as a consequence, dysfunction. Accumulated GAGs in respiratory system results in lung pathology and respiratory insufficiency in 56-63% of cases and is a leading cause of early mortality. Active storage of GAGs in the mucosa of the upper and lower respiratory tract, as well as in alveoli contributes to cellular dysfunction, fibrosis, and chronic airway obstruction or restriction. Typical morphological changes of MPS type VI: short neck, hypoplasia of the mandible, high epiglottis, macroglossia, mucus hypersecretion, hypertrophy of the adenoids and tonsils, tracheobronchomalacia and laryngomalacia, as well as multiple bone deformities of the chest and decreased respiratory muscle tone worsen the respiratory impairment.
Objective: To study the nature of respiratory dysfunction in patients with MPS type VI based on spirography results.
Materials and methods: A retrospective analysis of the medical records of 5 patients diagnosed with MPS type VI who were under medical supervision in the Scientific Center of Pediatrics and Surgery. All children underwent complex instrumental examination of cardiovascular, central nerve systems and ENT organs. To assess respiratory function, all patients had spirography using a BTL-08 Spiro (BTL, Newcastle-under-Lyme, United Kingdom). The following parameters were measured: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC ratio (Tiffeneau index), peak expiratory flow rate (PEF), and mid-expiratory flow rate (MEF) – MEF 75, MEF 50, and MEF 25.
Results: According to spirography data, all 5 patients with MPS type VI had mixed respiratory dysfunction: three patients had a predominantly restrictive component, while in two cases obstructive component prevailed. Regarding the severity of respiratory dysfunction, three patients had severe respiratory dysfunction, and two had moderate respiratory dysfunction.
Discussion: Respiratory dysfunction is frequent clinical manifestation in MPS VI and a leading cause of mortality. Active accumulation of GAGs in the tissues of upper and lower respiratory tract is main cause of respiratory impairment in MPS VI patients. Additionally accumulated GAGs lead to narrowing of the craniovertebral junction, resulting in spinal cord compression and the development of respiratory disorders. According to the results of international studies conducted on patients with MPS VI, respiratory dysfunction was identified in 100% of cases. Predominantly it was obstruction of upper and lower airways, while restrictive respiratory dysfunction was registered less common. Positive correlation was calculated (p < 0.01) between severity of respiratory dysfunction and age of patient, likely due to disease progression. However, according to data we obtained, the restrictive component predominated in 60% of patients with MPS VI, and we didn’t identify strong correlation between severity of respiratory dysfunction and age. Since, our work was conducted on a small group of patients (n = 5), it is inaccurate to extrapolate it to a wide population of patients with MPS VI, and therefore further observation with a larger sample is required.
Conclusion: According to spirography data, all patients had mixed respiratory dysfunction, with severity ranging from moderate to severe. Restrictive respiratory dysfunction predominated in 60% of cases, while obstructive dysfunction in 40%. Given that respiratory impairment in patients with MPS VI is strongly associated with a high risk of severe complications and mortality, regular monitoring of pulmonary function is crucial.
Keywords: mucopolysaccharidosis, spirography, respiratory dysfunction, obstruction, restriction.
