Among other things, the present disclosure provides oligonucleotides, compositions, and methods thereof. Among other things, the present disclosure encompasses the recognition that structural elements of oligonucleotides, such as base sequence, chemical modifications (e.g., modifications of sugar, base, and/or internucleotidic linkages) or patterns thereof, conjugation with additional chemical moieties, and/or stereochemistry [e.g., stereochemistry of backbone chiral centers (chiral internucleotidic linkages)], and/or patterns thereof, can have significant impact on oligonucleotide properties and activities, e.g., knockdown ability, stability, delivery, etc. In some embodiments, the oligonucleotides decrease the expression, activity and/or level of a C9orf72 gene, including but not limited to, one comprising a repeat expansion, or a gene product thereof. In some embodiments, the present disclosure provides methods for treatment of diseases using provided oligonucleotide compositions, for example, in treatment of C9orf72-related disorders.
