Brain morphological abnormalities in children with cyclin-dependent kinase-like 5 deficiency disorder

Neurophysiological and brain structural insights into cyclin-dependent kinase-like 5 deficiency disorder: Visual and auditory evoked potentials and MRI analysis

OBJECTIVE

CDKL5 deficiency disorder (CDD), an epileptic encephalopathy for which novel therapeutics are under development, lacks valid and reliable measures of therapeutic efficacy. We aimed to elucidate the neurophysiological and brain structural features of CDD patients and identify objective indicators reflecting the clinical severity.

METHODS

Twelve CDD patients and 12 healthy controls (HCs) participated. The clinical severity of CDD was scored using the CDD severity assessment (CDD-SA). The participants underwent visual evoked potential (VEP), auditory brainstem response (ABR), structural MRI, and diffusion tensor imaging (DTI) analyses. Measurements from each modality were compared with normal values of age-matched cohorts (VEP and ABR) or statistically compared between CDD patients and HCs (MRI).

RESULTS

VEP showed a significant correlation between P100 latency and CDD-SA in CDD patients. ABR showed abnormalities in six patients (50%), including prolonged V-wave latency (n = 2), prolonged inter-peak latency between waves I and V (n = 3), and mild hearing loss (n = 4). Structural MRI showed a significant reduction in cortical volume in the left pars triangularis and right cerebellum compared with HCs. DTI showed a widespread decrease in fractional anisotropy and an increase in mean and radial diffusivity compared with HCs.

CONCLUSION

CDD patients had reduced cortical volume in the left pars triangularis, a brain region crucial for speech, and one-third of patients had mild hearing loss. These changes may be involved in language impairments in CDD patients. Additionally, P100 latency significantly correlated with the clinical severity. These features can be used to assess the clinical severity of CDD.

Growth patterns in individuals with CDKL5 deficiency disorder

AIM

To compare growth in individuals with cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder with population norms and to investigate the effect of gastrostomy on growth.

METHOD

The longitudinal study included 353 individuals from the International CDKL5 Disorder Database with any anthropometric measurement in baseline and/or follow-up questionnaires. The British 1990 growth reference was used to determine the age- and sex-standardized z-score. Repeated cross-sectional data were fitted using a Gaussian linear regression model with generalized estimating equations.

RESULTS

All growth parameters were below the general population norm (mean z-scores: weight -0.97, height -0.65, body mass index [BMI] -0.81, head circumference -2.12). The disparity was particularly pronounced for all anthropometric measurements after 4 years of age except for BMI. Moreover, individuals with gastrostomy placement were shown to have a larger decrease than those without.

INTERPRETATION

In addition to weight, height, and BMI, head circumference was also compromised in this disorder. Microcephaly could be considered a helpful diagnostic feature, especially in adults. Any benefit of gastrostomy on weight and BMI was mainly seen in the early years.

CDKL5 deficiency disorder: progressive brain atrophy may be part of the syndrome

The clinical phenotype of Cyclin-Dependent Kinase-Like 5 (CDKL5) deficiency disorder (CDD) has been delineated but neuroimaging features have not been systematically analyzed. We studied brain magnetic resonance imaging (MRI) scans in a cohort of CDD patients and reviewed age at seizure onset, seizure semiology, head circumference. Thirty-five brain MRI from 22 unrelated patients were included. The median age at study entry was 13.4 years. In 14/22 patients (85.7%), MRI in the first year of life was unremarkable in all but two. In 11/22, we performed MRI after 24 months of age (range 2.5-23 years). In 8 out of 11 (72.7%), MRI showed supratentorial atrophy and in six cerebellar atrophy. Quantitative analysis detected volumetric reduction of the whole brain (-17.7%, P-value = 0.014), including both white matter (-25.7%, P-value = 0.005) and cortical gray matter (-9.1%, P-value = 0.098), with a reduction of surface area (-18.0%, P-value = 0.032), mainly involving the temporal regions, correlated with the head circumference (ρ = 0.79, P-value = 0.109). Both the qualitative structural assessment and the quantitative analysis detected brain volume reduction involving the gray and white matter. These neuroimaging findings may be related to either progressive changes due to CDD pathogenesis, or to the extreme severity of epilepsy, or both. Larger prospective studies are needed to clarify the bases for the structural changes we observed.

CDKL5 deficiency disorder: clinical features, diagnosis, and management

CDKL5 deficiency disorder (CDD) was first identified as a cause of human disease in 2004. Although initially considered a variant of Rett syndrome, CDD is now recognised as an independent disorder and classified as a developmental epileptic encephalopathy. It is characterised by early-onset (generally within the first 2 months of life) seizures that are usually refractory to polypharmacy. Development is severely impaired in patients with CDD, with only a quarter of girls and a smaller proportion of boys achieving independent walking; however, there is clinical variability, which is probably genetically determined. Gastrointestinal, sleep, and musculoskeletal problems are common in CDD, as in other developmental epileptic encephalopathies, but the prevalence of cerebral visual impairment appears higher in CDD. Clinicians diagnosing infants with CDD need to be familiar with the complexities of this disorder to provide appropriate counselling to the patients' families. Despite some benefit from ketogenic diets and vagal nerve stimulation, there has been little evidence that conventional antiseizure medications or their combinations are helpful in CDD, but further treatment trials are finally underway.

Therapeutic potential of pregnenolone and pregnenolone methyl ether on depressive and CDKL5 deficiency disorders: Focus on microtubule targeting

Pregnenolone methyl-ether (PME) is a synthetic derivative of the endogenous neuroactive steroid pregnenolone (PREG), which is an important modulator of several brain functions. In addition to being the precursor of steroids, PREG acts directly on various targets including microtubules (MTs), the functioning of which is fundamental for the development and homeostasis of nervous system. The coordination of MT dynamics is supported by a plethora of MT-associated proteins (MAPs) and by a specific MT code that is defined by the post-translational modifications of tubulin. Defects associated with MAPs or tubulin post-translational modifications are linked to different neurological pathologies including mood and neurodevelopmental disorders. In this review, we describe the beneficial effect of PME in major depressive disorders (MDDs) and in CDKL5 deficiency disorder (CDD), two pathologies that are joint by defective MT dynamics. Growing evidence indeed suggests that PME, as well as PREG, is able to positively affect the MT-binding of MAP2 and the plus-end tracking protein CLIP170 that are both found to be deregulated in the above mentioned pathologies. Furthermore, PME influences the state of MT acetylation, the deregulation of which is often associated with neurological abnormalities including MDDs. By contrast to PREG, PME is not metabolised into other downstream molecules with specific biological properties, an aspect that makes this compound more suitable for therapeutic strategies. Thus, through the analysis of MDDs and CDD, this work focuses attention on the possible use of PME for neuronal pathologies associated with MT defects.

Sodium channel blockers for the treatment of epilepsy in CDKL5 deficiency disorder: Findings from a multicenter cohort

OBJECTIVE

This study was aimed to analyze the effectiveness of sodium channel blockers (SCBs) in CDKL5 deficiency disorder (CDD)-related epilepsy.

METHODS

A retrospective, observational study was performed, including patients with CDD diagnosis evaluated between 2016 and 2019 at three tertiary Epilepsy Centers. Demographic, electroclinical and genetic features, as well as ASM treatments and their outcomes were analyzed, with special focus on SCBs.

RESULTS

Twenty-one patients evaluated at three tertiary Epilepsy Centers were included, of which 19 presented with epilepsy (90.5%); all had pathogenic mutations of CDKL5. Six patients (31.6%) were classified as SCB responders (more than 50% reduction), four being currently seizure free (mean seizure-free period of 8 years). Most frequent SCB drugs were oxcarbazepine (OXC), carbamazepine (CBZ), and lacosamide (LCM). None of them presented relevant adverse events. In contrast, three patients showed seizure aggravation in the non-responder group. When comparing both groups, responders had statistically significant younger age at SCB treatment and epilepsy onset, higher proportion of focal epileptiform activity and less frequent history of West syndrome.

CONCLUSIONS

The results of this study indicate that treatment with SCBs might be effective and safe in a subset of patients with CDD-related epilepsy.