Genetic Epilepsy

Gene: KCND2

Green List (high evidence)

6 new unrelated cases with developmental delay reported in PMID: 34245260 (Zhang et al 2021), 3 of whom had seizures. All had heterozygous missense variants of KCND2 in sites known to be critical for channel gating (E323K, P403A, two individuals, V404L, two individuals and V404M). Functional studies suggest that these missense changes cause both a partial loss-of-function (LOF) and gain-of-function (GOF). The V404 change appears to increase epileptic seizure susceptibility with the 3 patients with a V404 change showing this phenotype.

PMID:24501278 - Lee et al, 2014 - reports pair of monozygotic twin boys with infantile onset severe refractory epilepsy and autism. A de novo heterozygous missense variant was identified by WES - V404M.

PMID: 29581270 - Lin et al, 2018 - performed functional work that shows V404M enhances inactivation of channels that have not yet opened and dramatically impairs the inactivation of channels that have opened.

PMID:16934482 - Singh et al, 2006 - reports a patient with cognative impairment who also went on to have seizures starting from age 13 with a 5 bp deletion in KCND2 leading to premature stop codon. The proband's asymptomatic father also shared this variant.
Sources: Literature

Created: 13 Dec 2021, 10:07 a.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted

Phenotypes
Neurodevelopmental disorder MONDO:0700092; global developmental delay, HP:0001263; seizure, HP:0001250

Publications

• 24501278
• 16934482
• 29581270
• 34245260

Green List (high evidence)

6 new unrelated cases with developmental delay reported in PMID: 34245260 (Zhang et al 2021), 3 of whom had seizures. All had heterozygous missense variants of KCND2 in sites known to be critical for channel gating (E323K, P403A, two individuals, V404L, two individuals and V404M). Functional studies suggest that these missense changes cause both a partial loss-of-function (LOF) and gain-of-function (GOF). The V404 change appears to increase epileptic seizure susceptibility with the 3 patients with a V404 change showing this phenotype.

PMID:24501278 - Lee et al, 2014 - reports pair of monozygotic twin boys with infantile onset severe refractory epilepsy and autism. A de novo heterozygous missense variant was identified by WES - V404M.

PMID: 29581270 - Lin et al, 2018 - performed functional work that shows V404M enhances inactivation of channels that have not yet opened and dramatically impairs the inactivation of channels that have opened.

PMID:16934482 - Singh et al, 2006 - reports a patient with cognative impairment who also went on to have seizures starting from age 13 with a 5 bp deletion in KCND2 leading to premature stop codon. The proband's asymptomatic father also shared this variant.
Sources: Literature

Created: 12 Dec 2021, 12:47 p.m.

Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown

Phenotypes
global developmental delay, HP:0001263; seizure, HP:0001250

Publications

• 24501278
• 16934482
• 29581270
• 34245260

Mode of pathogenicity
Other