Cognitive impairments in inherited metabolic diseases: Promises and challenges

Clinical and biochemical footprints of inherited metabolic disorders. VII. Ocular phenotypes

Ocular manifestations are observed in approximately one third of all inherited metabolic disorders (IMDs). Although ocular involvement is not life-threatening, it can result in severe vision loss, thereby leading to an additional burden for the patient. Retinal degeneration with or without optic atrophy is the most frequent phenotype, followed by oculomotor problems, involvement of the cornea and lens, and refractive errors. These phenotypes can provide valuable clues that contribute to its diagnosis. In this issue we found 577 relevant IMDs leading to ophthalmologic manifestations. This article is the seventh of a series attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

Detailed profile of cognitive dysfunction in children with aspartylglucosaminuria

Aspartylglucosaminuria (AGU) is a rare, recessively inherited lysosomal disease with relatively high prevalence in Finnish population. This progressive disease has a vast impact on patient's cognition and physical health, leading to intellectual disability and shorter life expectancy. Cognitive functions of 21 7- to 14-year-old children with AGU were studied cross-sectionally using Wechsler's Intelligence Scale for Children IV and the results were compared with a standardized Finnish sample. In addition to overall cognitive performance, abilities in discrete cognitive domains, including verbal comprehension, perceptual reasoning, working memory, and processing speed, were examined. The results showed that despite the very low overall level of cognitive performance, there were notable differences between individuals. All those children whose performance was closer to their own age level were 7 to 10 years old. Processing speed appeared more compromised, as compared with verbal comprehension. Furthermore, examining the subtest raw scores, there were no significant positive correlations between age and subtest scores, suggesting that the developmental level of AGU children could be rather stable throughout ages 7 to 14. This study gives insight to the severe nature of AGU disease. Since younger children performed better compared to their age norms than older children, the results raise a question whether the highest peak in cognitive functions is reached at an earlier age than previously thought.