Phenotypes of mosaic mutation of PCDH19 gene caused epilepsy in boys / 中华实用儿科临床杂志

ABSTRACT

Objective:To summarize the clinical phenotype and gene mutation characteristics of male patients with epilepsy caused by mosaic PCDH19 mutation. Methods:The clinical data of 3 male patients with epilepsy caused by mosaic PCDH19 mutation were analyzed.Microdroplet digital polymerase chain reaction (mDDPCR) was used for the detection of mosaicism in the three probands and their family members.Relevant literatures were reviewed. Results:The seizure onset age were 5 months, 9 months and 6 months of life respectively.Focal seizures occurred in 2 cases and multiple seizure types occurred in 1 case.Three patients presented with clusters of seizures.Fever sensitivity was observed in 2 cases out of the 3 cases.Two patients had intellectual disability and 1 patient had autistic manifestation.The clinical phenotype in 2 patient fulfilled the diagnosis of Dravet syndrome. PCDH19 mosaic mutations c. 317T>A(p.M106K), c.158dupT(p.D54Gfs*35) and c. 1639G>C(p.A547P) were detected respectively, and were identified as de novo after parental validation.Mutant allele fractions (MAF) in the blood samples were identified as 81.18%, 37.08%, 77.64%, respectively.The MAF of multiple tissues in 1 patient varied from 78.67% to 98.46%.Review of literature revealed that a total of 11 cases with mosaic PCDH19 mutation were reported.Among them, seizure onset occurred between 5 and 31 months of age.Focal seizures occurred in 9 cases, 3 cases of the 9 cases had only focal seizures.Generalized tonic clonic seizures occurred in 4 cases.Two or more seizures were observed in 6 cases.Clustering of seizures was found in all patient and sensitivity to fever was observed in 9 patients.Seven patients had mild to severe intellectual disability and 5 patients had autistic features. Conclusions:The clinical phenotypes of male patients with epilepsy caused by PCDH19 mosaic mutation are characterized by clustering of seizures, sensitivity to fever, focal seizures in most cases, varied degree of intellectual disability and autistic features in partial.