CDKL5 and ARX Mutations in Males With Early-Onset Epilepsy

Mutations in CDKL5 and ARX are known causes of early-onset epilepsy and severe developmental delay in males and females. Although numerous males with ARX mutations associated with various phenotypes have been reported in the literature, the majority of CDKL5 mutations have been identified in females with a phenotype characterized by early-onset epilepsy, severe global developmental delay, absent speech, and stereotypic hand movements. To date, only 10 males with CDKL5 mutations have been reported. Our retrospective study reports on the clinical, neuroimaging, and molecular findings of 18 males with early-onset epilepsy caused by either CDKL5 or ARX mutations. These 18 patients include eight new males with CDKL5 mutations and 10 with ARX mutations identified through sequence analysis of 266 and 346 males, respectively, at our molecular diagnostic laboratory. Our large dataset therefore expands on the number of reported males with CDKL5 mutations and highlights that aberrations of CDKL5 and ARX combined are an important consideration in the genetic forms of early-onset epilepsy in boys.     

Brief Report: MECP2 Mutations in People Without Rett Syndrome

Mutations in Methyl-CpG-Binding protein 2 (MECP2) are commonly associated with the neurodevelopmental disorder Rett syndrome (RTT). However, some people with RTT do not have mutations in MECP2, and interestingly there have been people identified with MECP2 mutations that do not have the clinical features of RTT. In this report we present four people with neurodevelopmental abnormalities and clear RTT-disease causing MECP2 mutation but lacking the characteristic clinical features of RTT. One patient’s symptoms suggest an extension of the known spectrum of MECP2 associated phenotypes to include global developmental delay with obsessive compulsive disorder and attention deficit hyperactivity disorder. These results reemphasize that RTT should remain a clinical diagnosis, based on the recent consensus criteria.     

Expression of a Secretable,Cell-Penetrating CDKL5 Protein Enhances the Efficacy of Gene Therapy for CDKL5 Deficiency Disorder

Although delivery of a wild-type copy of the mutated gene to cells represents the most effective approach for a monogenic disease, proof-of-concept studies highlight significant efficacy caveats for treatment of brain disorders. Herein, we develop a cross-correction-based strategy to enhance the efficiency of a gene therapy for CDKL5 deficiency disorder, a severe neurodevelopmental disorder caused by CDKL5 gene mutations. We created a gene therapy vector that produces an Igk-TATk-CDKL5 fusion protein that can be secreted via constitutive secretory pathways and, due to the cell-penetration property of the TATk peptide, internalized by cells. We found that, although AAVPHP.B_Igk-TATk-CDKL5 and AAVPHP.B_CDKL5 vectors had similar brain infection efficiency, the AAVPHP.B_Igk-TATk-CDKL5 vector led to higher CDKL5 protein replacement due to secretion and penetration of the TATk-CDKL5 protein into the neighboring cells. Importantly, Cdkl5 KO mice treated with the AAVPHP.B_Igk-TATk-CDKL5 vector showed a behavioral and neuroanatomical improvement in comparison with vehicle or AAVPHP.B_CDKL5 vector-treated Cdkl5 KO mice. In conclusion, we provide the first evidence that a gene therapy based on a cross-correction approach is more effective at compensating Cdkl5-null brain defects than gene therapy based on the expression of the native CDKL5, opening avenues for the development of this innovative approach for other monogenic diseases. Supplementary InformationThe online version contains supplementary material available at 10.1007/s13311-022-01295-8.     

Respiratory and sleep disorders in female children with atypical Rett syndrome caused by mutations in the CDKL5 gene

Aim In female children with drug‐resistant seizures and developmental delay from birth, atypical Rett syndrome caused by mutations in the CDKL5 gene should be considered. Several clinical features resemble classic Rett syndrome. Respiratory and sleep abnormalities are frequently present in Rett syndrome, whereas little is known in patients with CDKL5 mutations. Method In four genetically confirmed female patients with CDKL5 mutations (age range 2–15y), the presence of breathing and sleep abnormalities was evaluated using the validated Sleep Disturbance Scale for Children and polysomnography (PSG). Results The Sleep Disturbance Scale for Children indicated disorders of initiating and maintaining sleep, daytime somnolence, and sleep breathing disorders. In one patient, PSG showed central apnoeas during sleep: her total apnoea–hypopnoea index (AHI) was 4.9, of which the central AHI was 3.4/h. When awake, central apnoeas were present in two of the four female children (central AHI 28/h and 41/h respectively), all preceded by hyperventilation. PSG showed low rapid eye movement (REM) sleep (9.7–18.3%), frequent awakenings, and low sleep efficiency (range 59–78%). Interpretation Episodic hyperventilation followed by central apnoeas was present while awake in two of four patients. This may indicate failure of brainstem respiratory centres. In addition, low REM sleep, frequent arousals (not caused by apnoeas/seizures), and low sleep efficiency were present. Similar to Rett syndrome, in patients with CDKL5 mutations PSG seems warranted to evaluate breathing and sleep disturbances.     

Aspects of Attention in Rett Syndrome

BackgroundWe sought to examine fundamental aspects of attention in children with Rett syndrome, a severely disabling neurodevelopmental disorder caused by spontaneous mutations in the X-linked MECP2 gene. To gauge their attention, we used eye tracking, which bypasses the profound impairments in expressive language and hand use in Rett syndrome. We report two aspects of attention—shifting and sustaining—basic abilities known to drive cognitive growth.MethodsTwo groups were compared: those with Rett syndrome (N = 20; 3-15 years) and a typically developing comparison group (N = 14; 3-16 years), using a task in which an attractive central stimulus was followed, after a short gap, by a dynamic target presented to one side. Time to shift to the target location (reactive and anticipatory saccades) and time fixating the target were assessed.ResultsChildren with Rett syndrome were consistently slower to shift (largely because of fewer anticipations); their reactive saccades were also slower than those of typically developing children, but not significantly so. The Rett syndrome group spent considerable time looking at the target (over 75% of available time), although significantly less so than the typically developing group.ConclusionsThese findings indicate that children with Rett syndrome could maintain attention on a stimulus and orient relatively quickly to the appearance of a target in the visual field. However, they had difficulty in anticipating predictable events, a difficulty in endogenous attention that is likely to have deleterious implications for executive functioning.     

Melkersson-Rosenthal综合征(附3例报告)

目的 探讨Melkersson-Rosenthal综合征（MRS）的临床特点及发病机制。方法 分析本院近10年来收治的3例完全型MRS患者临床及随访资料。结果 3例患者临床资料符合完全性MRS的诊断，即间歇性面瘫、再生性唇面肿及皱襞舌，其中1例有家族性皱襞舌。结论 MRS发病机制可能与免疫功能异常所致组织炎性肉芽肿有关，激素治疗有效。     

Parental view of epilepsy in Rett Syndrome

Few instruments exist to measure the impact of epilepsy on the quality of life in Rett Syndrome (RS). METHODS: We attended to describe seizures characteristics, parental opinion and quality of life related in RS by using a newly developed self administered questionnaire, postal sent to parents of French Association for Rett Syndrome (AFSR). RESULTS: Two-hundred completed questionnaires were returned. Mean age of patients was 14.8+/-8.1 years [3-42]. Parents reported that 70% of children had epileptic and non-epileptic seizures and mean age at first seizures was 7.3+/-5.1 years [1-24]. No statistical difference was found between the ages of first seizures, diagnosis of epilepsy and introduction of treatment. Seizures had a negative impact on child and family's life (68% of cases), strongly correlated to the existence of generalized, prolonged, cyanotic and drug-resistant seizures, on the child's level of alertness and progress in communication skills and psycho-social consequences such as fear of seizures, and difficulties to find home care aids. CONCLUSIONS: We identified major concerns of parents with RS that determine the impact of seizures on children and their family's quality of life. Our results suggest that in order to improve seizures management in RS, better information should reduce fear about seizures and should improve the quality of life of RS.     

Epilepsy in Rett syndrome,and CDKL5‐ and FOXG1‐gene–related encephalopathies

Rett syndrome is an X‐linked neurodevelopmental disorder that manifests in early childhood with developmental stagnation, and loss of spoken language and hand use, with the development of distinctive hand stereotypies, severe cognitive impairment, and autistic features. About 60% of patients have epilepsy. Seizure onset before the age of 3 years is unlikely, and onset after age 20 is rare. Diagnosis of Rett syndrome is based on key clinical elements that identify “typical” Rett syndrome but also “variant” or “atypical” forms. Diagnostic criteria have been modified only slightly over time, even after discovering that MECP2 gene alterations are present in >90% of patients with typical Rett syndrome but only in 50–70% of atypical cases. Over the last several years, intragenic or genomic alterations of the CDKL5 and FOXG1 genes have been associated with severe cognitive impairment, early onset epilepsy and, often, dyskinetic movement disorders, which have variably been defined as Rett variants. It is now clearly emerging that epilepsy has distinctive characteristics in typical Rett syndrome and in the different syndromes caused by CDKL5 and FOXG1 gene alterations. The progressive parting of CDKL5‐ and FOXG1‐gene–related encephalopathies from the core Rett syndrome is reflected by the effort to produce clearer diagnostic criteria for typical and atypical Rett syndrome. Efforts to characterize the molecular pathology underlying these developmental encephalopathies are pointing to abnormalities of telencephalic development, neuronal morphogenesis, maturation and maintenance, and dendritic arborization.     

Update on Novel CCM Gene Mutations in Patients with Cerebral Cavernous Malformations

Cerebral cavernous malformations (CCMs) are lesions affecting brain microvessels. The pathogenesis is not clearly understood. Conventional classification criterion is based on genetics, and thus, familial and sporadic forms can be distinguished; however, classification of sporadic cases with multiple lesions still remains uncertain. To date, three CCM causative genes have been identified: CCM1/KRIT1, CCM2/MGC4607 and CCM3/PDCD10. In our previous mutation screening, performed in a cohort of 95 Italian patients, with both sporadic and familial cases, we identified several mutations in CCM genes. This study represents further molecular screening in a cohort of 19 Italian patients enrolled by us in the few last years and classified into familial, sporadic and sporadic with multiple lesions cases. Direct sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis were performed to detect point mutations and large genomic rearrangements, respectively. Effects of detected mutations and single-nucleotide polymorphisms (SNPs) were evaluated by an in silico approach and by western blot analysis. A novel nonsense mutation in CCM1 and a novel missense mutation in CCM2 were detected; moreover, several CCM2 gene polymorphisms in sporadic CCM patients were reported. We believe that these data enrich the mutation spectrum of CCM genes, which is useful for genetic counselling to identify both familial and sporadic CCM cases, as early as possible.     

The spectrum of phenotypes in females with Rett Syndrome

Since the discovery of mutations in the methyl-CpG binding protein-2 (MECP2) gene in Rett Syndrome (RTT) a large number of females have been diagnosed worldwide. In this article we present the clinical and developmental data of 120 RTT females with mutations in the MECP2 gene and individually describe typical and atypical cases. We found a broad spectrum of phenotypes in females. At the severest end we have females with primary developmental delay who never learned to turn, sit or walk and who developed severe epilepsy. At the mildest end of the spectrum, there are females with only minor neurological symptoms who have good gross motor function, speak and have relatively well-preserved hand function. A number of girls either do not fulfil all the necessary diagnostic criteria or present with symptoms that have not been described in RTT before. Comparing our data with the normal population we found that girls with RTT have a smaller occipito-frontal circumference, shorter length and lower weight at birth. As a result of molecular genetic analysis a broad spectrum of phenotypes in RTT females has evolved. We found evidence that the defect in MeCP2 influences the somatic growth before birth.     

Case Report: Complicated Molecular Diagnosis of MECP2 Gene Structural Rearrangement in a Proband with Rett Syndrome

Journal of Autism and Developmental Disorders -     

Development of a Video-based Evaluation Tool in Rett Syndrome

This paper describes the development of a video-based evaluation tool for use in Rett syndrome (RTT). Components include a parent-report checklist, and video filming and coding protocols that contain items on eating, drinking, communication, hand function and movements, personal care and mobility. Ninety-seven of the 169 families who initially agreed to participate returned a videotape within 8 months of the first request. Subjects whose videos were returned had a similar age profile to those who did not provide a video but were more likely to have classical than atypical RTT. Evidence of the content and social validity and inter-rater reliability on 11 videos is provided. Video may provide detailed, objective assessment of function and behaviour in RTT.     

Novel microsatellite DNA markers for Indian Gharial (Gavialis gangeticus)

The present status of existing crocodile species has increased the necessity to develop novel utilities for conservation. We have developed 18 microsatellite loci from the Indian Gharial (Gavialis gangeticus) intended for genomic explanation and applied them to study genetic variation. Polymorphism of each locus was assessed in 32 individuals for G. gangeticus India. The number of alleles per locus varied from 2 to 8 (mean 5.5) for Indian population. Observed and expected heterozygosity ranged from 0.73 to 1.00 and 0.50 to 0.81, respectively and the average polymorphic information content is 0.565. These selected markers are helpful for assessing population structure, intraspecific difference, and conservation and management of G. gangeticus.