Table 6. [Notable KCNQ2 Pathogenic Variants]. - GeneReviews®

Reference Sequences	DNA Nucleotide Change	Predicted Protein Change	Comment [Reference]
NM_172107.4 NP_742105.1	c.593G>A	p.Arg198Gln	Assoc w/unique phenotype: no neonatal seizures, infantile spasms w/hypsarrhythmia on EEG at age 4-6 mos; subsequent DD & moderate-to-severe ID [Millichap et al 2017, Yang et al 2019, Liu et al 2021]
c.601C>T	p.Arg201Cys	Assoc w/neonatal onset of profound encephalopathy, apparent weak respiratory drive, myoclonic-appearing mvmts w/o ictal EEG changes, & severe-to-profound DD [Mulkey et al 2017, Olson et al 2017, Kojima et al 2018]
c.602G>A	p.Arg201His
c.821C>T	p.Thr274Met	Assoc w/KCNQ2-NEO-DEE. Among most frequently reported in literature [Weckhuysen et al 2012, Milh et al 2013, Orhan et al 2014, Milh et al 2015, Millichap et al 2016, Hortigüela et al 2017, Olson et al 2017, Zhang et al 2017, Borlot et al 2019, Maghera et al 2020] & in gene-specific databases (RIKEE)
c.881C>T	p.Ala294Val	Assoc w/KCNQ2-NEO-DEE; milder phenotype is noted if variant is assoc w/mosaicism [Milh et al 2015]. Among most frequently reported in literature [Steinlein et al 2007, Kato et al 2013, Milh et al 2013, Allen et al 2014, Abidi et al 2015, Milh et al 2015, Pisano et al 2015, Millichap et al 2016, Hortigüela et al 2017, Olson et al 2017, Parrini et al 2017, Chen et al 2018, Kothur et al 2018] & gene-specific databases (RIKEE)
c.916G>A	p.Ala306Thr	Assoc w/KCNQ2-SLFNE [Ronen et al 1993, Singh et al 1998, Soldovieri et al 2014], incl in the largest 6-generation family reported, w/69 affected persons

Reference
Sequences

DNA
Nucleotide
Change

Predicted
Protein
Change

Comment [Reference]

c.593G>A

p.Arg198Gln

Assoc w/unique phenotype: no neonatal seizures, infantile spasms w/hypsarrhythmia on EEG at age 4-6 mos; subsequent DD & moderate-to-severe ID [Millichap et al 2017, Yang et al 2019, Liu et al 2021]

c.601C>T

p.Arg201Cys

Assoc w/neonatal onset of profound encephalopathy, apparent weak respiratory drive, myoclonic-appearing mvmts w/o ictal EEG changes, & severe-to-profound DD [Mulkey et al 2017, Olson et al 2017, Kojima et al 2018]

c.602G>A

p.Arg201His

c.821C>T

p.Thr274Met

Assoc w/KCNQ2-NEO-DEE. Among most frequently reported in literature [Weckhuysen et al 2012, Milh et al 2013, Orhan et al 2014, Milh et al 2015, Millichap et al 2016, Hortigüela et al 2017, Olson et al 2017, Zhang et al 2017, Borlot et al 2019, Maghera et al 2020] & in gene-specific databases (RIKEE)

c.881C>T

p.Ala294Val

Assoc w/KCNQ2-NEO-DEE; milder phenotype is noted if variant is assoc w/mosaicism [Milh et al 2015]. Among most frequently reported in literature [Steinlein et al 2007, Kato et al 2013, Milh et al 2013, Allen et al 2014, Abidi et al 2015, Milh et al 2015, Pisano et al 2015, Millichap et al 2016, Hortigüela et al 2017, Olson et al 2017, Parrini et al 2017, Chen et al 2018, Kothur et al 2018] & gene-specific databases (RIKEE)

c.916G>A

p.Ala306Thr

Assoc w/KCNQ2-SLFNE [Ronen et al 1993, Singh et al 1998, Soldovieri et al 2014], incl in the largest 6-generation family reported, w/69 affected persons

From: KCNQ2-Related Disorders

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