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01.12.2015 | Research | Ausgabe 1/2015 Open Access

Journal of Neurodevelopmental Disorders 1/2015

A 13-year follow-up of Finnish patients with Salla disease

Journal of Neurodevelopmental Disorders > Ausgabe 1/2015
Liisa E. Paavola, Anne M. Remes, Marika J. Harila, Tarja T. Varho, Tapio T. Korhonen, Kari Majamaa
Wichtige Hinweise

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

LP was responsible for the design of the study, performed the neuropsychological investigations and statistical analyses, and drafted the manuscript. MH participated in the design of the study, performed the statistical analyses, and helped to draft the manuscript. AR performed the neurological investigations and advised with the manuscript, describing the results and combining the neuropsychological, clinical, and neurological data. TV advised in interpreting and describing the results and helped to draft the manuscript. TK supervised the neuropsychological design and helped to draft the manuscript. KM supervised the design of the study, participated in the analysis, interpretation, and description of the results, and critically revised the manuscript. All authors read and approved the final manuscript.



Salla disease (SD) is a rare lysosomal storage disorder leading to severe intellectual disability. SD belongs to the Finnish disease heritage, and it is caused by mutations in the SLC17A5 gene. The aim of the study was to investigate the course of neurocognitive features of SD patients in a long-term follow-up.


Neuropsychological and neurological investigations were carried out on 24 SD patients, aged 16–65 years, 13 years after a similar examination.


The survival analysis showed excess mortality among patients with SD after the age of 30 years. The course of the disease was progressive, but follow-up of SD patients revealed that motor skills improved till the age of 20 years, while mental abilities improved in most patients till 40 years of age. Verbal comprehension skills did not diminish during the follow-up, but productive speech deteriorated because of dyspraxia and dysarthria. Motor deficits were marked. Ataxia was prominent in childhood, but it was replaced by athetotic movements during the teens. Spasticity became more obvious with age especially in severely disabled SD patients.


Younger SD patients performed better in almost every task measuring mental abilities that then seem to remain fairly constant till early sixties. Thus, the results indicate better prognosis in cognitive skills than earlier assumed. There is an apparent decline in motor skills after the age of 20 years. The early neurocognitive development predicts the later course of motor and cognitive development.
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