Here, we report that de novo missense mutations in CDKL5 are associated with a severe phenotype of early-onset infantile spasms and clinical features that overlap those of other neurodevelopmental disorders, such as Rett syndrome and Angelman syndrome.
Mutations in the CDKL5 gene (also known as STK9) have recently been shown to cause early onset epilepsy and severe mental retardation (ISSX or West syndrome).
X-linked cyclin-dependent kinase-like 5 (CDKL5 or STK9) has recently been implicated in atypical Rett and X-linked West syndromes, severe neurological disorders associated with mental retardation, loss of communication and motor skills and infantile spasms and seizures in predominantly females.
CDKL5 mutations are a significant cause of infantile spasms and early epileptic seizures in female patients, and of a later intractable seizure disorder, irrespective of whether they have suspected Rett syndrome.
Epilepsy with mutation of the CDKL5 gene causes early seizures and is a variant of Rett syndrome (MIM (312750), which is reported typically as infantile spasms.
Although the phenotype of CDKL5 mutation is similar to Rett syndrome caused by MECP2 mutation, the former is characterized by early-onset seizures and association with West syndrome.
CDKL5 mutations are a significant cause of infantile spasms and early epileptic seizures in female patients, and of a later intractable seizure disorder, irrespective of whether they have suspected Rett syndrome.
A screen for CDKL5 mutations is useful in patients, mainly females, with a history of early onset intractable seizures and becomes mandatory when idiopathic infantile spasms and/or atypical Rett syndrome features are also present.
Interestingly these missense mutations that result in a mislocalisation of the CDKL5 protein are associated with severe developmental delay which was apparent within the first months of life characterised by early and generalised hypotonia, and autistic features, and as well as early infantile spasms.
Importantly, one member of the family, CDKL5, has been implicated in atypical Rett syndrome, West syndrome, and X-linked infantile spasm, all including MR as a manifestation.
In conclusion, our report show that search for mutations in CDKL5 is indicated in girls with early onset of a severe intractable seizure disorder or infantile spasms with severe hypotonia, and in girls with RTT-like phenotype and early onset seizures, though, in our cohort, mutations in CDKL5 account for about 10% of the girls affected by these disorders.
In conclusion, our report show that search for mutations in CDKL5 is indicated in girls with early onset of a severe intractable seizure disorder or infantile spasms with severe hypotonia, and in girls with RTT-like phenotype and early onset seizures, though, in our cohort, mutations in CDKL5 account for about 10% of the girls affected by these disorders.
Mutations in the human X-linked cyclin-dependent kinase-like 5 (CDKL5) gene have been shown to cause severe neurodevelopmental disorders including infantile spasms, encephalopathy, West-syndrome and an early-onset variant of Rett syndrome.
In this study we screened several cohorts of children for CDKL5 mutations, totaling 316 patients, including individuals with a clinical diagnosis of RTT but who were negative for MECP2 mutations (n=102), males with X-linked mental retardation (n=9), patients with West syndrome (n=52), patients with autism (n=59), patients with epileptic encephalopathy (n=33), patients with Aicardi syndrome (n=7) and other patients with intellectual disability with or without seizures (n=54).
Mutations of the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) cause an X-linked encephalopathy with early onset intractable epilepsy, including infantile spasms and other seizure types, and a Rett syndrome (RTT)-like phenotype.
Mutations in the cyclin-dependent kinase-like 5 gene (CDKL5) have been described in epileptic encephalopathies in females with infantile spasms with features that overlap with Rett syndrome.