Jennifer Kearney
Last active: 5/27/2014

Mapping genetic modifiers of survival in a mouse model of Dravet syndrome.

Miller AR, Hawkins NA, McCollom CE, Kearney JA
Genes Brain Behav. 2014 13 (2): 163-72

PMID: 24152123 · PMCID: PMC3930200 · DOI:10.1111/gbb.12099

Epilepsy is a common neurological disorder affecting approximately 1% of the population. Mutations in voltage-gated sodium channels are responsible for several monogenic epilepsy syndromes. More than 800 mutations in the voltage-gated sodium channel SCN1A have been reported in patients with generalized epilepsy with febrile seizures plus and Dravet syndrome. Heterozygous loss-of-function mutations in SCN1A result in Dravet syndrome, a severe infant-onset epileptic encephalopathy characterized by intractable seizures, developmental delays and increased mortality. A common feature of monogenic epilepsies is variable expressivity among individuals with the same mutation, suggesting that genetic modifiers may influence clinical severity. Mice with heterozygous deletion of Scn1a (Scn1a(+/-) ) model a number of Dravet syndrome features, including spontaneous seizures and premature lethality. Phenotype severity in Scn1a(+/-) mice is strongly dependent on strain background. On the 129S6/SvEvTac strain Scn1a(+/-) mice exhibit no overt phenotype, whereas on the (C57BL/6J × 129S6/SvEvTac)F1 strain Scn1a(+/-) mice exhibit spontaneous seizures and early lethality. To systematically identify loci that influence premature lethality in Scn1a(+/-) mice, we performed genome scans on reciprocal backcrosses. Quantitative trait locus mapping revealed modifier loci on mouse chromosomes 5, 7, 8 and 11. RNA-seq analysis of strain-dependent gene expression, regulation and coding sequence variation provided a list of potential functional candidate genes at each locus. Identification of modifier genes that influence survival in Scn1a(+/-) mice will improve our understanding of the pathophysiology of Dravet syndrome and may suggest novel therapeutic strategies for improved treatment of human patients.

© 2013 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

MeSH Terms (9)

Animals Chromosomes Epilepsies, Myoclonic Genes, Modifier Mice Mice, Inbred C57BL NAV1.1 Voltage-Gated Sodium Channel Penetrance Quantitative Trait Loci

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