Otorhinolaryngological manifestations in 61 patients with mucopolysaccharidosis

The diagnosis and management of mucopolysaccharidosis type II

Mucopolysaccharidosis type II (MPS II) is a rare X-linked recessive inherited lysosomal storage disease. With pathogenic variants of the IDS gene, the activity of iduronate-2-sulfatase (IDS) is reduced or lost, causing the inability to degrade glycosaminoglycans (GAGs) in cells and influencing cell function, eventually resulting in multisystemic manifestations, such as a coarse face, dysostosis multiplex, recurrent respiratory tract infections, and hernias. Diagnosing MPS II requires a combination of clinical manifestations, imaging examinations, urinary GAGs screening, enzyme activity, and genetic testing. Currently, symptomatic treatment is the main therapeutic approach. Owing to economic and drug availability issues, only a minority of patients opt for enzyme replacement therapy or hematopoietic stem cell transplantation. The limited awareness of the disease, the lack of widespread detection technology, and uneven economic development contribute to the high rates of misdiagnosis and missed diagnosis in China.

Adenotonsillar pathology in mucopolysaccharidoses - lysosomal storage predominates in paracortical CD63+ cells

Despite the adenoids are regularly removed in patients with mucopolysaccharidoses (MPS), the underlying tissue and cellular pathologies remain understudied. We characterized an (immuno)histopathologic and ultrastructural phenotype dominated by lysosomal storage changes in a specific subset of adenotonsillar paracortical cells in 8 MPS patients (3 MPS I, 3 MPS II, and 2 MPS IIIA). These abnormal cells were effectively detected by an antibody targeting the lysosomal membrane tetraspanin CD63. Important, CD63+ storage vacuoles in these cells lacked the monocytes/macrophages lysosomal marker CD68. Such a distinct patterning of CD63 and CD68 was not present in a patient with infantile neurovisceral variant of acid sphingomyelinase deficiency. The CD63+ storage pathology was absent in two MPS I patients who either received enzyme-replacement therapy or underwent hematopoietic stem cells transplantation prior the adenoidectomy. Our study demonstrates novel features of lysosomal storage patterning and suggests diagnostic utility of CD63 detection in adenotonsillar lymphoid tissue of MPS patients.

Endoscopic and Image Analysis of the Airway in Patients with Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis (MPS) is a hereditary disorder arising from lysosomal enzymes deficiency, with glycosaminoglycans (GAGs) storage in connective tissues and bones, which may compromise the airway. This retrospective study evaluated patients with MPS type IVA with airway obstruction detected via endoscopy and imaging modalities and the effects of surgical interventions based on symptoms. The data of 15 MPS type IVA patients (10 males, 5 females, mean age 17.8 years) were reviewed in detail. Fiberoptic bronchoscopy (FB) was used to distinguish adenotonsillar hypertrophy, prolapsed soft palate, secondary laryngomalacia, vocal cord granulation, cricoid thickness, tracheal stenosis, shape of tracheal lumen, nodular deposition, tracheal kinking, tracheomalacia with rigid tracheal wall, and bronchial collapse. Computed tomography (CT) helped to measure the deformed sternal angle, the cross-sectional area of the trachea, and its narrowest/widest ratio (NW ratio), while angiography with 3D reconstruction delineated tracheal torsion, kinking, or framework damage and external vascular compression of the trachea. The NW ratio correlated negatively with age (p < 0.01), showing that airway obstruction progressed gradually. Various types of airway surgery were performed to correct the respiratory dysfunction. MPS type IVA challenges the management of multifactorial airway obstruction. Preoperative airway evaluation with both FB and CT is strongly suggested to assess both intraluminal and extraluminal factors causing airway obstruction.

Airway Findings in Patients with Hunter Syndrome Treated with Intravenous Idursulfase

People with Hunter syndrome are known to be affected by a variety of airway pathologies. Treatment of Hunter syndrome with the enzyme replacement therapy (ERT) idursulfase is now the standard of care. However, it is not known how ERT changes the progression of airway involvement. To evaluate this, we performed a retrospective analysis of bronchoscopies performed on children with Hunter syndrome who were part of intrathecal ERT trials. Findings for airway pathology were extracted from bronchoscopy reports and analyses were performed for cross-sectional and longitudinal changes in airway disease. One-hundred and thirty bronchoscopies from 23 subjects were analyzed. Upper airway disease (adenoid hypertrophy and/or pharyngomalacia) was reported in 93% and 87% of bronchoscopies, respectively. Laryngeal abnormalities were recognized in 46% of cases. There were lower airway (tracheal and or bronchial) findings in 64% of all bronchoscopies and prevalence increased with age. Evaluations over time adjusted for repeat evaluations showed that increasing airway involvement was associated with older age (p = 0.0007) despite ongoing ERT. No association was discovered between age of intravenous ERT initiation and progression of airway disease. Individuals with Hunter syndrome who are receiving intravenous enzyme replacement therapy showed the progression of airways disease supporting the need for regular airway monitoring and intervention.

Sanfilippo Syndrome: Optimizing Care with a Multidisciplinary Approach

Sanfilippo syndrome, or mucopolysaccharidosis type III (MPS III), is a disease grouping five genetic disorders, four of them occurring in humans and one known to date only in a mouse model. In every subtype of MPS III (designed A, B, C, D or E), a lack or drastically decreased activity of an enzyme involved in the degradation of heparan sulfate (HS) (a compound from the group of glycosaminoglycans (GAGs)) arises from a genetic defect. This leads to primary accumulation of HS, and secondary storage of other compounds, combined with changes in expressions of hundreds of genes and many defects in organelles and various biochemical processes in the cell. As a result, dysfunctions of tissues and organs occur, leading to severe symptoms in patients. Although changes in somatic organs are considerable, the central nervous system is especially severely affected, and neurological, cognitive and behavioral disorders are the most significant changes, making the disease enormously burdensome for patients and their families. In the light of the current lack of any registered therapy for Sanfilippo syndrome (despite various attempts of many research groups to develop effective treatment, still no specific drug or procedure is available for MPS III), optimizing care with a multidisciplinary approach is crucial for managing this disease and making quality of patients’ life passable. This includes efforts to make/organize (i) accurate diagnosis as early as possible (which is not easy due to various possible misdiagnosis events caused by similarity of MPS III symptoms to those of other diseases and variability of patients), (ii) optimized symptomatic treatment (which is challenging because of complexity of symptoms and often untypical responses of MPS III patients to various drugs), and (iii) psychological care (for both patients and family members and/or caregivers). In this review article, we focus on these approaches, summarizing and discussing them.

Hearing Loss in Patients With Morquio Syndrome: Protocol for a Scoping Review

Background

Mild to moderate hearing loss is common in patients with mucopolysaccharidosis (MPS) IVA. The hearing loss can be conductive, sensorineural, or mixed. However, in these patients, the mixed form is frequent, attributed to the combination of conductive and neurosensory elements, with slowly progressive evolution. Conductive hearing loss may be secondary to recurrent upper respiratory tract infections, serous otitis media, and deformities of the ear ossicles due to the accumulation of glycosaminoglycans (GAGs). Meanwhile, the sensorineural form is mainly attributed to the accumulation of GAGs in the auditory system.

Objective

The aim of this scoping review is to understand the extent and type of evidence in relation to the physiopathology, classification, epidemiology, and clinical management of hearing loss and the effect of therapy for hearing loss in patients with MPS IVA.

Methods

This scoping review includes participants across all genders and of no particular age group who are diagnosed with MPS IVA and develop hearing loss as a comorbidity. No exclusion criteria (country, language, or document type) will be applicable. The information sources will include experimental and quasi-experimental, analytical observational, observational, and qualitative studies. Unpublished literature will not be covered. Grey literature will be covered. A total of 2 independent reviewers will participate in the process of screening the literature, paper selection, and data extraction, and this process will be performed blindly. When all manuscripts have been selected, disagreements that arise between the 2 reviewers at each stage of the selection process will be resolved through discussion or with an additional reviewer. Results will be reported with descriptive statistics and information will be displayed in a diagrammatic or tabular manner, as explained in the JBI guidelines.

Results

The literature search was performed in November 2021 in MEDLINE, LILACS (Literatura Latino-Americana e do Caribe em Ciências da Saúde), the Cochrane Library, ScienceDirect, Google Scholar, and OpenGrey; a total of 780 results were retrieved. Completion of the review is expected in mid-2022.

Conclusions

This scoping review will be the first to describe the extent of the information regarding the development of hearing loss in the MPS IVA population. The data gathered by this review may lead to an understanding of the grade of hearing loss in this population and allow for the assessment of possible interventions according to the disease pattern.

International Registered Report Identifier (IRRID)

PRR1-10.2196/32986

Otorhinolaryngological Management in Taiwanese Patients with Mucopolysaccharidoses

Background: Mucopolysaccharidoses (MPSs) are lysosomal storage disorders wherein glycosaminoglycans accumulate because the enzymes that degrade them are insufficient. The earliest symptoms, which are the main reasons for seeking consultation, are otorhinolaryngological and commonly occur in MPS I, II, IV, and VI. This retrospective study aimed to determine the occurrence of otorhinolaryngological manifestations in MPS patients in Taiwan and to analyze the prognosis of surgical intervention, including its effect on symptoms. Methods: We reviewed 42 patients (30 males and 12 females), with a median age of 20.5 years, who had MPS (16.7% type I, 35.7% type II, 19.0% type IIIB, 21.4% type IVA, and 7.2% type VI). The following otorhinolaryngological manifestations were collected: annual number of upper respiratory tract infections (URTIs) and otitis media with effusion (OME) episodes, adenoid size, tonsillar size, and apnea-hypopnea index (AHI). Results: Among 42 patients, we found recurrent otitis media in 42.9% of the patients, hearing loss in 83.3% (mixed: 52.4%, conductive: 21.4%, and sensorineural: 9.5%), frequent URTIs in 47.6%, and obstructive sleep apnea syndrome in 35.7%. Moreover, 76% of the patients underwent ear, nose, and throat (ENT) surgery, including adenoidectomy, tonsillectomy, tympanostomy with ventilation tube insertion, tracheotomy, and supraglottoplasty. Conclusions: MPS patients had a high incidence of ENT problems. ENT surgery reduced the severity of hearing loss, degree of symptoms related to upper airway obstruction, and severity of respiratory tract and otological infections of patients with MPS.

Hearing Loss in Mucopolysaccharidoses: Current Knowledge and Future Directions

Mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by a deficiency of one of the enzymes involved in the degradation of glycosaminoglycans. Hearing loss is a common clinical presentation in MPS. This paper reviews the literature on hearing loss for each of the seven recognized subtypes of MPS. Hearing loss was found to be common in MPS I, II, III, IVA, VI, and VII, and absent from MPS IVB and MPS IX. MPS VI presents primarily with conductive hearing loss, while the other subtypes (MPS I, MPS II, MPS III, MPS IVA, and MPS VII) can present with any type of hearing loss (conductive, sensorineural, or mixed hearing loss). The sensorineural component develops as the disease progresses, but there is no consensus on the etiology of the sensorineural component. Enzyme replacement therapy (ERT) is the most common therapy utilized for MPS, but the effects of ERT on hearing function have been inconclusive. This review highlights a need for more comprehensive and multidisciplinary research on hearing function that includes behavioral testing, objective testing, and temporal bone imaging. This information would allow for better understanding of the progression and etiology of hearing loss. Owing to the prevalence of hearing loss in MPS, early diagnosis of hearing loss and annual comprehensive audiological evaluations are recommended.