Repeat Expansions with Small TTTCA Insertions in MARCHF6 Cause Familial Myoclonus without Epilepsy.

ABSTRACT:

Background

Familial adult myoclonus epilepsy (FAME) is a rare autosomal dominant disorder caused by the same intronic TTTTA/TTTCA repeat expansion in seven distinct genes. TTTTA-only expansions are benign, whereas those containing TTTCA insertions are pathogenic.

Objective

We investigated the genetic basis of dominant cortical myoclonus without seizures in two unrelated families.

Methods

Repeat-primed polymerase chain reaction (PCR), long-range PCR, and nanopore sequencing were used to detect and characterize expansions at known FAME loci.

Results

We identified a novel repeat expansion in MARCHF6, comprising 388 to 454 elongated TTTTA repeats and 5 to 11 TTTCA repeats at the 3'-terminus, segregating with cortical myoclonus in 8 affected individuals. This config

SUBMITTER: Kuhnel T 

PROVIDER: S-EPMC12273606 | biostudies-literature | 2025 Jul

REPOSITORIES: biostudies-literature