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α-Mannosidosis (β-Mannosidosis)
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
α-Mannosidosis is an autosomal recessive disease, and affected offspring have been of both sexes [8]. The gene has been assigned to chromosome 9 [36] to the central region between p13.2 and q12 [2, 37]. It contains 24 exons. The mutation p.R750W has accounted for 27 percent of disease producing alleles in 16 countries [5, 38]. Eighty-three novel mutations were identified extending the mutant spectrum to 125. The mutation at nucleotide 212 leads to the H71L amino acid change [6]. Two other mutations were reported [39] in two homozygous Italian patients with α-mannosidosis, IVS-2A>G and 322-323insA. The first led to skipping of exon 21. The second caused a frame shift with a stop codon at amino acid 160. A 47-year-old Japanese woman with a homozygous C>T change in exon 19 leading to R760X had less than 1 percent of 99 control enzyme activities [7]. Q639X and R750W were found in a 7-year-old Finnish boy [7].
Lens and cataracts
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Mannosidosis AR condition due to deficiency in alpha mannosidase.Spoke-shaped posterior cataracts.
A novel genetic variant potentially altering the expression of MANBA in the cerebellum associated with attention deficit hyperactivity disorder in Han Chinese children
Published in The World Journal of Biological Psychiatry, 2022
Xinzhen Chen, Ting Yao, Jinliang Cai, Qi Zhang, Shanyawen Li, Huiru Li, Xihang Fu, Jing Wu
The MANBA-encoded protein beta-mannosidase is a member of the glycosyl hydrolase 2 family, which functions as the final exo-acting β-glycosidase in the pathway for N-linked glycoprotein oligosaccharide catabolism (Gytz et al. 2019). Expression localisation analysis of MANBA in brain tissues shows that MANBA is primarily restricted to the midbrain and hindbrain, including the cerebellar cortex, medulla and pons (Yu et al. 2015). There is a low level of MANBA expression during all stages of human brain development (Yu et al. 2015), the activity of which decreases with age (Cooper et al. 1987). To date, there have been few studies on MANBA and neuropsychiatric disorders. Previous studies have reported that the expression level of MANBA in hippocampal neurons of schizophrenia patients is reduced (Altar et al. 2005), and genetic variants of MANBA are correlated with treatment response in schizophrenia (Ovenden et al. 2017). Recently, Rodriguez-Fontenla and Carracedo (2021) identified MANBA as a risk gene for autism spectrum disorder (ASD) through TWAS. However, the genetic mechanism and the potential role of beta-mannosidase in the development and progression of these neuropsychiatric diseases have not been reported yet. Similarly, this is the first identification of the association between MANBA genetic variants and childhood ADHD, and the contribution of this gene and its variants to the pathogenesis of ADHD is not yet known. Previous studies have showed that genetic defects in beta-mannosidase protein can result in beta-mannosidosis, a type of lysosomal storage disorder (LSD) (Wenger et al. 1986; Huynh et al. 2011), which is not only associated with a wide spectrum of peripheral neuropathy (Levade et al. 1994) but also implicated in various central nervous system (CNS) lesions, including mineralisation, especially in the cerebellum (Lovell and Jones 1983; 1985). Patients with these LSDs are often accompanied by psychiatric disturbances and cognitive impairments (Staretz-Chacham et al. 2010). Only about 20 severe beta-mannosidosis cases have been reported so far. Patients with beta-mannosidosis present heterogeneous clinical symptoms from childhood, including aggressiveness and hyperactivity (Staretz-Chacham et al. 2010; Gytz et al. 2019), one of the core symptoms of ADHD. In addition, developmental delay, mental retardation, speech impairment and seizures have also been reported (Gytz et al. 2019), all of which are comorbid or associated with ADHD (Bellani et al. 2011; Nickels et al. 2016; Ball et al. 2019; Sun et al. 2019). In addition, beta-mannosidase is very important for the development of the oculomotor nervous system, and its decreased activity is related to autosomal dominant nystagmus (Yu et al. 2015).