TY - JOUR
T1 - In vivo, in vitro and in silico correlations of four de novo SCN1A missense mutations
AU - Nissenkorn, Andreea
AU - Almog, Yael
AU - Adler, Inbar
AU - Safrin, Mary
AU - Brusel, Marina
AU - Marom, Milit
AU - Bercovich, Shayel
AU - Yakubovich, Daniel
AU - Tzadok, Michal
AU - Ben-Zeev, Bruria
AU - Rubinstein, Moran
N1 - Publisher Copyright: © 2019 Nissenkorn et al. This is an open access article distributed underthe terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2019/2
Y1 - 2019/2
N2 - Mutations in the SCN1A gene, which encodes for the voltage-gated sodium channel NaV1.1, cause Dravet syndrome, a severe developmental and epileptic encephalopathy. Genetic testing of this gene is recommended early in life. However, predicting the outcome of de novo missense SCN1A mutations is difficult, since milder epileptic syndromes may also be associated. In this study, we correlated clinical severity with functional in vitro electrophysiological testing of channel activity and bioinformatics prediction of damaging mutational effects. Three patients, bearing the mutations p.Gly177Ala, p.Ser259Arg and p. Glu1923Arg, showed frequent intractable seizures that had started early in life, with cognitive and behavioral deterioration, consistent with classical Dravet phenotypes. These mutations failed to produce measurable sodium currents in a mammalian expression system, indicating complete loss of channel function. A fourth patient, who harbored the mutation p. Met1267Ile, though presenting with seizures early in life, showed lower seizure burden and higher cognitive function, matching borderland Dravet phenotypes. In correlation with this, functional analysis demonstrated the presence of sodium currents, but with partial loss of function. In contrast, six bioinformatics tools for predicting mutational pathogenicity suggested similar impact for all mutations. Likewise, homology modeling of the secondary and tertiary structures failed to reveal misfolding. In conclusion, functional studies using patch clamp are suggested as a prognostic tool, whereby detectable currents imply milder phenotypes and absence of currents indicate an unfavorable prognosis. Future development of automated patch clamp systems will facilitate the inclusion of such functional testing as part of personalized patient diagnostic schemes.
AB - Mutations in the SCN1A gene, which encodes for the voltage-gated sodium channel NaV1.1, cause Dravet syndrome, a severe developmental and epileptic encephalopathy. Genetic testing of this gene is recommended early in life. However, predicting the outcome of de novo missense SCN1A mutations is difficult, since milder epileptic syndromes may also be associated. In this study, we correlated clinical severity with functional in vitro electrophysiological testing of channel activity and bioinformatics prediction of damaging mutational effects. Three patients, bearing the mutations p.Gly177Ala, p.Ser259Arg and p. Glu1923Arg, showed frequent intractable seizures that had started early in life, with cognitive and behavioral deterioration, consistent with classical Dravet phenotypes. These mutations failed to produce measurable sodium currents in a mammalian expression system, indicating complete loss of channel function. A fourth patient, who harbored the mutation p. Met1267Ile, though presenting with seizures early in life, showed lower seizure burden and higher cognitive function, matching borderland Dravet phenotypes. In correlation with this, functional analysis demonstrated the presence of sodium currents, but with partial loss of function. In contrast, six bioinformatics tools for predicting mutational pathogenicity suggested similar impact for all mutations. Likewise, homology modeling of the secondary and tertiary structures failed to reveal misfolding. In conclusion, functional studies using patch clamp are suggested as a prognostic tool, whereby detectable currents imply milder phenotypes and absence of currents indicate an unfavorable prognosis. Future development of automated patch clamp systems will facilitate the inclusion of such functional testing as part of personalized patient diagnostic schemes.
UR - http://www.scopus.com/inward/record.url?scp=85061232970&partnerID=8YFLogxK
U2 - https://doi.org/10.1371/journal.pone.0211901
DO - https://doi.org/10.1371/journal.pone.0211901
M3 - مقالة
C2 - 30735520
SN - 1932-6203
VL - 14
JO - PLoS ONE
JF - PLoS ONE
IS - 2
M1 - e0211901
ER -