Audiological and radiological study of eight polish patients with alpha-mannosidosis.

Alpha-mannosidase catalyze lysosomal cleaving of mannose residues from glycoproteins. The enzyme is encoded by the MAN2B1 gene. Biallelic pathogenic variants cause enzymatic deficiency, which clinically results in alpha-mannosidosis (AM), an autosomal recessively inherited condition. Typical features observed in AM patients include intellectual disability, loss of speech, dysmorphic features, progressive motor problems, ataxia, hearing impairment and recurrent otitis. The cause of the latter is mainly attributed to immunodeficiency. The aim of our study was to demonstrate the otolaryngologic and hearing outcomes in patients with AM. The study group consisted of 8 AM patients: 6 males and 2 females, aged 2.5-37 yrs. The clinical course, dysmorphic ENT features, hearing status and the HRCT scans of the temporal bones were analyzed. MS Excel for Windows and Statistica software package were used for the comparison of interaural audiometric loss, mean hearing loss and mean hearing threshold for each patient's audiometric frequency tested. We identified ENT dysmorphic features in all of our AM patients, while the hearing loss was detected in 6 out of our 8 patients. For those cases, the onset of deafness was noted in the first decade of life, this impairment was sensorineural, of cochlear origin, bilateral, of a moderate degree (mean loss 62.76 dB; median 60 dB, standard deviation 12.5 dB), symmetrical and stable. The shape of the audiometric curves of our patients can be described as slightly sloping towards the higher tested frequencies, with a marked improvement at 4 kHz. The radiological examination revealed normal structures of the ears, with the exception of one case where a persistent otitis generated a cochlear gap. We therefore concluded that the hearing loss in our AM patients derived from cochlear impairment unrelated with recurrent otitis.

White matter alteration and cerebellar atrophy are hallmarks of brain MRI in alpha-mannosidosis.

OBJECTIVE: Despite profound neurological symptomatology there are only few MRI studies focused on the brain abnormalities in alpha-mannosidosis (AM). Our aim was to characterize brain MRI findings in a large cohort of AM patients along with clinical manifestations. METHODS: Twenty-two brain MRIs acquired in 13 untreated AM patients (8 M/5F; median age 17 years) were independently assessed by three experienced readers and compared to 16 controls. RESULTS: Focal and/or diffuse hyperintense signals in the cerebral white matter were present in most (85%) patients. Cerebellar atrophy was common (62%), present from the age of 5 years. Progression was observed in two out of 6 patients with follow-up scans. Cortical atrophy (62%) and corpus callosum thinning (23%) were already present in a 13-month-old child. The presence of low T2 signal intensity in basal ganglia and thalami was excluded by the normalized signal intensity profiling. The enlargement of perivascular spaces in white matter (38%), widening of perioptic CSF spaces (62%), and enlargement of cisterna magna (85%) were also observed. Diploic space thickening (100%), mucosal thickening (69%) and sinus hypoplasia (54%) were the most frequent non-CNS abnormalities. CONCLUSION: White matter changes and cerebellar atrophy are proposed to be the characteristic brain MRI features of AM. The previously reported decreased T2 signal intensity in basal ganglia and thalami was not detected in this quantitative study. Rather, this relative MR appearance seems to be related to the diffuse high T2 signal in the adjacent white matter and not the gray matter iron deposition that has been hypothesized.

Comprehensive cardiopulmonary assessment in α mannosidosis.

INTRODUCTION: α Mannosidosis is an extremely rare, progressive, and complex lysosomal storage disease, characterized by mental retardation, hearing impairment, coarse facial features, skeletal abnormalities, and pulmonary involvement. While bone marrow transplantation has been the only therapeutic option to date, nowadays new treatment options are being explored, which may affect pulmonary and exercise capacity. AIM AND METHODS: To assess cardiopulmonary involvement in patients with α mannosidosis by pulmonary function tests, cardiopulmonary exercise testing, and low irradiation chest computed tomography (CT). RESULTS: Five patients aged 11 to 28 years were followed in our Respiratory-Metabolic Clinic. All five had pulmonary symptoms and received inhaled therapy. Three patients underwent bone marrow transplantation. Parenchymal lung disease was evident in 3/5 chest CT tests. Pulmonary function tests were abnormal in all patients and showed obstructive/restrictive impairment with air trapping. All five patients showed reduced peak oxygen uptake (median 23.1; range 20.4-32.2 mL/minute/kg, median %predicted 62; range %predicted 59-79). CONCLUSIONS: Pulmonary involvement is a known complication in this rare disease. Comprehensive cardiopulmonary evaluation is feasible among these patients and may help in assessing disease progression and response to new treatment modalities.

Intranasal dexmedetomidine and intravenous ketamine for procedural sedation in a child with alpha-mannosidosis: a magic bullet?

BACKGROUND: Procedural sedation is increasingly needed in pediatrics. Although different drugs or drugs association are available, which is the safest and most efficient has yet to be defined, especially in syndromic children with increased sedation-related risk factors. CASE REPORT: we report the case of a five-year-old child affected by alpha-mannosidosis who required procedural sedation for an MRI scan and a lumbar puncture. We administered intranasal dexmedetomidine (4 µg/kg) 45 min before intravenous cannulation, followed by one bolus of ketamine (1 mg/kg) for each procedure. The patient maintained spontaneous breathing and no desaturation or any complication occurred. CONCLUSION: intranasal dexmedetomidine and intravenous ketamine could be a feasible option for MRI and lumbar puncture in children with alpha-mannosidosis needing sedation.

Proton nuclear magnetic resonance spectroscopic detection of oligomannosidic n glycans in alpha-mannosidosis: a method of monitoring treatment.

In Alpha-mannosidosis (MIM 248500) the patients accumulate mainly unbranched oligosaccharide chains in the lysosomes in all body tissues, including the brain. With ensuing therapeutic modalities in man (BMT and ERT) non-invasive methods of monitoring the effect of treatment are needed. Paramount is the possible effect of the treatment on the brain, since this organ is regarded as difficult to reach because of the blood-brain barrier. We therefore performed proton nuclear magnetic resonance spectroscopy (MRS) of the brain in two untreated patients, and a 16-year-old patient treated with BMT at the age of 10 to assess whether this non-invasive method could be applied in the monitoring of the accumulation of abnormal chemicals in the brain of patients. We found an abnormal peak that was not present in the treated patient. A similar pattern was also found in MRS of urine from patients, reflecting the concentration of oligosaccharides in serum and tissues. We therefore conclude that MRS can be a useful method to monitor the effect of treatment for Alpha-Mannosidosis.

Bone marrow transplantation for the treatment of alpha-mannosidosis.

We report successful bone marrow transplantation in a child with a severe form of alpha-mannosidosis, type I. There was complete resolution of the recurrent sinopulmonary disease and organomegaly, improvement in the bony disease, and stabilization of neurocognitive function.

[Alpha-mannosidosis]. / Alfamannosidose.

Alpha-mannosidosis is a rare autosomal recessively inherited lysosomal storage disorder. We describe three patients with alpha-mannosidosis who were born in Tromsø between 1983 and 1987, in order to increase awareness of the disease. It is characterized by a typical facial look, with a prominent forehead, hypertelorism, small nose, flat nasal bridge and hypoplastic teeth. The patients are mentally retarded, often have dysostosis multiplex, recurrent infections and typically severe loss of hearing and delayed speech development. The disease is slowly progressive in the first decade, but shows considerable clinical variability. In most cases, the lymphocytes are vacuolized, but diagnosis depends on measurement of alpha-mannosidase activity in the lymphocytes. Prenatal diagnosis is available, based on chorionic villi sampling in the 9th to 11th week of pregnancy. No causal therapy is known, but establishment of the diagnosis is important to avoid complications, recognize hearing loss and provide speech therapy and special education. The specific diagnosis is critical for genetic counselling and prenatal diagnosis. The authors therefore outline the diagnostic strategy.

Mannosidosis: a study of two patients, presenting clinical heterogeneity.

Two unrelated patients suffering from mannosidosis, aged 9 and 33 years, are reported, presenting two extremes in the phenotypic expression of this lysosomal storage disorder. Clinical, radiological, biochemical and therapeutical aspects of the disease are discussed. Our patients support the concept that mannosidosis is not a homogeneous syndrome but manifests wide clinical heterogeneity.