In a study published recently in the Orphanet Journal of Rare Diseases, a team of researchers identified distinct variations in the neuroanatomical and neuropsychiatric phenotypes of cystinosis patients. Phenotype refers to visible, observable differences in certain traits that do not necessarily correspond with genetic variants. The findings from the study serve to reflect the significant variation in disease presentation among patients with cystinosis and also have implications that could impact decisions in disease management.
Cystinosis is a type of lysosomal storage disease which is characterized by the abnormal accumulation of the amino acid cystine in the body. The disease is caused by mutations affecting the CTNS gene. This disease leads to the formation of cystine crystals in different areas of the body, particularly the cornea. Severe cystinosis can cause major symptoms early in life, such as kidney failure, growth and developmental impairments, diabetes, muscle atrophy, reduced skin and hair pigment, blindness, impaired sweating, and inability to swallow. Treatment of cystinosis includes cysteamine, which can impair the growth of crystals in the body; sodium citrate is also used to control blood acidity. If kidney failure occurs, dialysis and ultimately a kidney transplant are necessary for survival. To learn more about cystinosis, click here.
About The Study
The study looked at a sample of 17 patients. Neuropsychiatric characteristics were measured with an IQ test, the Perceptual Reasoning Index (scores ranging from 63-109), and the Verbal Comprehension Index (scores ranging from 59-138). While IQ was in the normal range in the sample, patients showed lower than average scores on the other two tests. The researchers also determined that cystinosis patients had significant impairments in working memory as well. Over 70 percent of patients scored beneath the 50th percentile in visuospatial skill assessments also. MRI scans also revealed the cerebral atrophy was present in some patients; these patients tended to score lower on IQ tests.
Ultimately, the results demonstrate that patients can range broadly in neurological profile. As a result, the authors recommend neuropsychological assessments in pediatric patients in order to inform treatment decisions.