RESUMO
Hereditary 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.
RESUMO
BACKGROUND: Several studies suggested a significant role of epigenetic changes, including alterations in miRNA, histone modifications, and DNA methylation of α-synuclein (SNCA) in Parkinson's disease (PD) pathogenicity. As of yet, only very few studies have been carried out in this field in Africa and none in Sudan. MATERIALS AND METHODS: We collected DNA from 172 Sudanese individuals (90 cases, 82 controls) who donated saliva for DNA extraction (mean age of onset: 40.6 ± 22.4 years). A family history of PD was evident in 64 patients. DNA preparation and bisulfite sequencing of SNCAintron1 was performed as described earlier. RESULTS: Of the fourteen analyzed CpGs of SNCAintron1, CpGs 16-23 were hypomethylated in PD (P-value ranged from 0.023 to 0.003). P-values improved, when sporadic cases were excluded from the analysis. CONCLUSION: We identified the presence of a specific pattern of DNA methylation in a young Sudanese cohort of familial PD, which confirms the importance of the methylation of SNCAintron1 for PD. This phenomenon appears to be independent of ethnicity, the impact of environmental factors, drug history, or familial clustering.