A Swedish SCA34 family with late onset ataxia, cerebellar atrophy and ocular movement abnormalities with a novel mutation in ELOVL4

Background: To investigate the clinical and radiological presentation of anew ELOVL4mutation in a Swedish family.Methods:We compiled information on a Swedish family with 6 affectedmembers. Four of these had undergone neurological and radiological examinations. Two patients were independently analysed genetically bywhole exome or whole genome sequencing.Results: All examined affected family members showed slowly progressivecerebellar ataxia with balance impairment starting at between 42 and 70years, ocular movement disturbances with nystagmus, hypermetric saccades or vertical gaze palsy, and cerebellar atrophy on imaging. None of theaffected family members had erytrokeratodermia variabilis, but three haddry skin or psoriasis. Two members had seizures, one had intermittentmuscular cramps. One deceased obligate carrier had dementia and one ofthe members examined had mild cognitive dysfunction (MMSE 23/30). Oneindividual had poor night vision. One individual had a diagnosis ofschizophrenia since age 25 years. We identified a novel heterozygousvariant ELOVL4 c.511A>C, p.(Ile171Leu) (NM_022726.4) in affected individuals. When this was discovered in the first family member it was reported as a variant of uncertain significance (VUS). However, aftersegregation analysis and detailed clinical information for the entire family,the variant could be reclassified as likely pathogenic according to the ACMG classification system (PMID: 25741868) and Jarvik et al (PMID: 27236918).Conclusions: So far, including the present report, eight different ELOVL4-variants have been described in SCA34 patients. Our examinations provideadditional knowledge to the presentation of this rare neurodegenerativedisorder