Abstract
In clinical practice, respiratory function tests are difficult to perform in Morquio syndrome patients due to their characteristic skeletal dysplasia, small body size and lack of cooperation of young patients, where in some cases, conventional spirometry for pulmonary function is too challenging. To establish feasible clinical pulmonary endpoints and determine whether age impacts lung function in Morquio patients non-invasive pulmonary tests and conventional spirometry were evaluated. The non-invasive pulmonary tests: impulse oscillometry system, pneumotachography, and respiratory inductance plethysmography in conjunction with conventional spirometry were evaluated in twenty-two Morquio patients (18 Morquio A and 4 Morquio B) (7 males), ranging from 3 to 40 years of age. Twenty-two patients were compliant with non-invasive tests (100%) with the exception of IOS (81.8%-18 patients). Seventeen patients (77.3%) were compliant with spirometry testing. All subjects had normal vital signs at rest including >95% oxygen saturation, end tidal CO2 (38-44 mmHg), and age-appropriate heart rate (mean=98.3, standard deviation=19) (two patients were deviated). All patients preserved normal values in the impulse oscillometry system, pneumotachography, and respiratory inductance plethysmography, although predicted forced expiratory total (72.8±6.9 SE%) decreased with age and was below normal; phase angle (35.5±16.5°), %rib cage (41.6±12.7%), resonant frequency, and forced expiratory volume in 1 s/forced expiratory volume total (110.0±3.2 SE%) were normal and not significantly impacted by age. The proposed non-invasive pulmonary function tests are able to cover a greater number of patients (young patients and/or wheel-chair bound), thus providing a new diagnostic approach for the assessment of lung function in Morquio syndrome which in many cases may be difficult to evaluate. Morquio patients studied herein demonstrated no clinical or functional signs of restrictive and/or obstructive lung disease.
Highlights
Morquio syndrome is autosomal recessive disorders caused by deficiency of Nacetylgalactosamine-6-sulfate sulfatase (GALNS) (Mucopolysaccharidosis IVA, MPS IVA) and β-Galactosidase (GLB1) (Mucopolysaccharidosis IVB, MPS IVB)
Predicted forced expiratory volume total (%FEVTOT) was normal until 10 years of age; %FEVTOT decreased with age, showing a significant negative correlation between %FEVTOT and age (FEVTOT=−33.16 ln(Age)+161.88; R2=0.475) (Fig. 1A)
%FEVTOT was negatively correlated with body weight, indicating that the higher BMIs in patients with Morquio syndrome provide a detrimental impact on overall respiratory function
Summary
Morquio syndrome is autosomal recessive disorders caused by deficiency of Nacetylgalactosamine-6-sulfate sulfatase (GALNS) (Mucopolysaccharidosis IVA, MPS IVA) and β-Galactosidase (GLB1) (Mucopolysaccharidosis IVB, MPS IVB). Theses enzymes are required for the catabolism of the glycosaminoglycans (GAGs): chrondroitin-6-sulfate (C6S). Keratan sulfate (KS) [1,2,3]. The incidence varies among different populations from 1:76,000 to 1:640,000 live births [3,4,5,6,7,8]. Morquio syndrome includes skeletal dysplasia with short stature, kyphoscoliosis, platyspondyly, odontoid hypoplasia, genu valgum, pectus carinatum, and dental abnormalities. Autopsied trachea showed tracheomalacia but little evidence of narrow airway due to storage materials [9]. Difficulty of intubation and extubation was observed during the surgical procedure, which could be associated with tracheomalacia. Tracheomalacia can cause twisting, tortuous trachea, leading a high risk of anesthesia
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
