This report describes developmental and epileptic encephalopathy 7, a subtype of developmental and epileptic encephalopathy. The human gene implicated is KCNQ2, which encodes a neurally expressed voltage-gated potassium channel. KCNQ2 is also associated with benign familial neonatal seizures 1 (BFNS1; MIM:121200). There is one moderate-scoring fly ortholog, Dmel\KCNQ, for which multiple genetic reagents, including loss of function alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated.
UAS constructs of Hsap\KCNQ2 have been introduced into flies, including wild-type KCNQ2 and genes carrying variants associated with the human disease. See the 'Disease-Implicated Variants' table below.
Pan-neuronal RNAi knockdown of Dmel\KCNQ resulted in 40% lethality at pupal stages; adult escapers have a sharply reduced lifespan and exhibit bang-sensitive seizures. Functional complementation (heterologous rescue) of these phenotypes by coexpression of wild-type, but not mutant, Hsap\KCNQ2 has been demonstrated. Pan-glial RNAi knockdown of Dmel\KCNQ did not result in lethality or obvious behavioral defects.
[updated Nov. 2024 by FlyBase; FBrf0222196]
[DEVELOPMENTAL AND EPILEPTIC ENCEPHALOPATHY 7; DEE7](https://omim.org/entry/613720)
[POTASSIUM CHANNEL, VOLTAGE-GATED, KQT-LIKE SUBFAMILY, MEMBER 2; KCNQ2](https://omim.org/entry/602235)
Developmental and epileptic encephalopathy 7 (DEE7) is a neurologic disorder characterized by the onset of refractory seizures in early infancy, often in the neonatal period. Affected individuals have resultant delayed neurologic development and persistent neurologic abnormalities. EEG initially shows a burst suppression pattern, consistent with a clinical diagnosis of Ohtahara syndrome, which may later evolve to multifocal epileptiform activity. Brain imaging in some patients shows lesions in the basal ganglia. Seizures usually remit by age 3 or 4 years, with improvement of EEG abnormalities and possibly brain imaging abnormalities, but the severe neurologic deficits persist (summary by Borgatti et al., 2004, pubmed:15249611 and Weckhuysen et al., 2012). pubmed:22275249). [from MIM:613720; 2024.11.19]
Developmental and epileptic encephalopathy 7 (DEE7) is caused by heterozygous mutation in the KCNQ2 gene on chromosome 20q13. Mutation in the KCNQ2 gene can also cause benign familial neonatal seizures 1 (BFNS1; MIM:121200). [from MIM:613720; 2024.11.19]
The KCNQ2 gene encodes a voltage-gated potassium channel that is expressed in the brain (Biervert et al., 1998, pubmed:9430594). [from MIM:602235; 2024.11.19]
Many to one (many human to 1 Drosophila); KCNQ2 has one moderate-scoring Drosophila ortholog, KCNQ.
Moderate-scoring ortholog of human KCNQ2, KCNQ3, KCNQ4 and KCNQ5, low-scoring ortholog of KCNQ1 (1 Drosophila to many human).
