Acknowledgements: We are grateful to the genotyping and sequencing core facility of the Brain Institute (ICM, Paris, France) and the Pitié-Salpêtrière Post-Genomic Platform (P3S, Paris, France) for doing the next-generation sequencing and array genotyping, respectively. We thank Nicolas Auger, Claire-Sophie Davoine, Mélanie Papin and Lena Guillot-Noel for their advice and Prof. Michel Koenig, Dr. Marine Guillaud-Bataille, and Dr. Guillaume Banneau for their help in nucleotide repeat expansion detection.Funder: The Association Connaitre les Syndromes Cérébelleux ASL-HSP-France patient association Ministry of Higher Education, Sudan French Embassy, SudanFunder: The Ministry of Higher Education, Sudan and the French Embassy, SudanHereditary spinocerebellar degenerations (SCDs) is an umbrella term that covers a group of monogenic conditions that share common pathogenic mechanisms and include hereditary spastic paraplegia (HSP), cerebellar ataxia, and spinocerebellar ataxia. They are often complicated with axonal neuropathy and/or intellectual impairment and overlap with many neurological conditions, including neurodevelopmental disorders. More than 200 genes and loci inherited through all modes of Mendelian inheritance are known. Autosomal recessive inheritance predominates in consanguineous communities; however, autosomal dominant and X-linked inheritance can also occur. Sudan is inhabited by genetically diverse populations, yet it has high consanguinity rates. We used next-generation sequencing, genotyping, bioinformatics analysis, and candidate gene approaches to study 90 affected patients from 38 unrelated Sudanese families segregating multiple forms of SCDs. The age-at-onset in our cohort ranged from birth to 35 years; however, most patients manifested childhood-onset diseases (the mean and median ages at onset were 7.5 and 3 years, respectively). We reached the genetic diagnosis in 63% and possibly up to 73% of the studied families when considering variants of unknown significance. Combining the present data with our previous analysis of 25 Sudanese HSP families, the success rate reached 52-59% (31-35/59 families). In this article we report candidate variants in genes previously known to be associated with SCDs or other phenotypically related monogenic disorders. We also highlight the genetic and clinical heterogeneity of SCDs in Sudan, as we did not identify a major causative gene in our cohort, and the potential for discovering novel SCD genes in this population
