Sanfilippo disease (mucopolysaccharidosis, MPS IIIA) is one of the types of mucopolysaccharidosis associated with extensive neurological effects and somatic symptoms. The consequences of neurodegeneration and cognitive impairment are manifested in challenges with the daily functioning of patients who experience problems with communication and following instructions. The aim of this study was to assess the cognitive functioning of three patients with MPS IIIA and to find patterns of neurodegeneration and to make their environment more friendly. Three boys (from 5.5 to 7 years) with MPS IIIA participated in the study. Each participant attended two meetings, and his functioning was assessed by three independent person (using two-way mirror). We used Bayley’s Scale III with some modifications. Interviews with parents were also included. The communication of patients was limited to some vocalizations. Patients presented instrumental use of items, but not all of them were able to repeat actions after diagnostician or presented object permanence. The results showed that the cognitive functioning of participants was significantly hindered by problems related to motor dysfunction, hyperactivity, and ataxia. The psychological data was collated with medical results. This study allows indicating new sources giving the possibility of child phenotype variability and to create specific interventions in the field of psychological therapy for patients with MPS IIIA and their families.

Background Sanfilippo syndrome B (or mucopolysaccharidosis type IIIB [MPS IIIB]) is a severe inherited metabolic disorder caused by mutations in the NAGLU gene, encoding α‐N‐acetylglucosaminidase. Dysfunction of this enzyme results in impaired degradation of heparan sulfate, one of glycosaminoglycans, and accumulation of this complex carbohydrate in lysosomes. Severe symptoms occurring in this disease are related to progressive neurodegeneration and include extreme hyperactivity, sleeping problems, aggressive‐like behavior, reduced fear, and progressive mental and cognitive deterioration. No cure is currently available for Sanfilippo disease. Methods Clinical characterization of the patient's symptoms has been performed. Biochemical analyses included glycosaminoglycan level determination and measurement of α‐N‐acetylglucosaminidase activity. Molecular analyses included exome sequencing and detailed analysis of the NAGLU gene. Psychological tests included assessment of attention, communication and behavior. Results We describe a patient with an untypically mild phenotype, who was diagnosed at the age of 13 years. Many cognitive, communication, and motoric functions were preserved in this patient, contrary to vast majority of those suffering from MPS IIIB. The patient is a compound heterozygote (c.638C>T/c.889C>T) in the NAGLU gene, and relatively high residual activity (about 25%) of α‐N‐acetylglucosaminidase was measured in serum (while no activity of this enzyme could be detected in dry blood spot). Conclusions We suggest that the mild phenotype might arise from the partially preserved function of the mutant enzyme (p.Pro213Leu), suggesting the genotype‐phenotype correlation in this case.

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Until now, only a few studies have focused on the early onset of symptoms of alkaptonuria (AKU) in the pediatric population. This prospective, longitudinal study is a comprehensive approach to the assessment of children with recognized AKU during childhood. The study includes data from 32 visits of 13 patients (five males, eight females; age 4–17 years) with AKU. A clinical evaluation was performed with particular attention to eye, ear, and skin pigmentation, musculoskeletal complaints, magnetic resonance imaging (MRI), and ultrasound (US) imaging abnormalities. The cognitive functioning and adaptive abilities were examined. Molecular genetic analyses were performed. The most common symptoms observed were dark urine (13/13), followed by joint pain (6/13), and dark ear wax (6/13). In 4 of 13 patients the values obtained in the KOOS‐child questionnaire were below the reference values. MRI and US did not show degenerative changes in knee cartilages. One child had nephrolithiasis. Almost half of the children with AKU (5/13) presented deficits in cognitive functioning and/or adaptive abilities. The most frequent HGD variants observed in the patients were c.481G>A (p.Gly161Arg) mutation and the c.240A>T (p.His80Gln) polymorphism. The newly described allele of the HGD gene (c.948G>T, p.Val316Phe) which is potentially pathogenic was identified.