Alpha-Mannosidosis: A Novel Cause of Bilateral Thalami and Dentate Nuclei Hyperintensity

Abstract

Alpha-mannosidosis is a rare autosomal recessive lysosomal storage disorder caused by mutations in the MAN2B1 gene. 1 To date, a total of 154 variants have been identified in 191 patients worldwide. 1 Symptoms usually begin in childhood, but milder forms may present only in adulthood. The most frequent systemic findings include skeletal abnormalities (81%), facial dysmorphia (70%), deafness (67%), immunodeficiency (recurrent respiratory tract infections; 53%), and organomegaly (namely, hepatosplenomegaly; 41%). 2 Nervous system involvement not only includes intellectual disability (>90%) but also psychomotor developmental regression, behavioral alterations and ataxia. 2 Brain magnetic resonance imaging (MRI) data is limited, with leukodystrophy and cerebellar atrophy representing the most frequently reported abnormalities. 3 Clinical-imaging descriptions are relevant to prompt recognition of this potentially treatable entity.Herein is presented the case of a 49-year-old female patient born from healthy consanguineous parents. Birth and perinatal periods were unremarkable and motor and language acquisitions followed normal milestones. At the age of 7, psychomotor regression was noticed after a normal first year at primary school, as well as gait impairment and speech and learning difficulties. Around the same period, hearing loss was also perceived. At the age of 14, the patient presented bilateral tonic−clonic seizures. In subsequent years, the clinical picture was dominated by intellectual disability and the girl was never capable of attending school or working. At the age of 42, she was referred to our Neurology Department for the first time, due to cognitive deterioration, aggressiveness, and frequent falls. Medical history included hepatosplenomegaly, metrorrhagia, and early menopause. Bone abnormalities and past recurrent infections were denied. Neurological examination revealed cognitive delay, poor spontaneous speech, axial, and appendicular choreo-dystonic movements, axial instability, and ataxic gait. Facial dysmorphia was also notorious, comprising low set ears, prognathism, and high

Molecular basis of neurocognitive dysfunction and psychosis in Alpha-Mannosidosis

“…Upon the analysis of MRI brain images of 13 patients with AM, Majovska et al concluded that white matter changes and cerebellar atrophy are proposed to be the characteristic brain MRI features in this condition [Figure 2] [30] .…”