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Aim: To differentiate phenotypic features of individuals with CDKL5 deficiency disorder (CDD) from those of individuals with other infantile‐onset epilepsies. Method: We performed a retrospective cohort study and ascertained individuals with CDD and comparison individuals with infantile‐onset epilepsy who had epilepsy gene panel testing. We reviewed records, updated variant classifications, and compared phenotypic features. Wilcoxon rank‐sum tests and χ2 or Fisher's exact tests were performed for between‐cohort comparisons. Results: We identified 137 individuals with CDD (110 females, 80.3%; median age at last follow‐up 3 year 11 months) and 313 individuals with infantile‐onset epilepsies (156 females, 49.8%; median age at last follow‐up 5 years 2 months; 35% with genetic diagnosis). Features reported significantly more frequently in the CDD group than in the comparison cohort included developmental and epileptic encephalopathy (81% vs 66%), treatment‐resistant epilepsy (95% vs 71%), sequential seizures (46% vs 6%), epileptic spasms (66% vs 42%, with hypsarrhythmia in 30% vs 48%), regression (52% vs 29%), evolution to Lennox–Gastaut syndrome (23% vs 5%), diffuse hypotonia (72% vs 36%), stereotypies (69% vs 11%), paroxysmal movement disorders (29% vs 17%), cerebral visual impairment (94% vs 28%), and failure to thrive (38% vs 22%). Interpretation: CDD, compared with other suspected or confirmed genetic epilepsies presenting in the first year of life, is more often characterized by a combination of treatment‐resistant epilepsy, developmental and epileptic encephalopathy, sequential seizures, spasms without hypsarrhythmia, diffuse hypotonia, paroxysmal movement disorders, cerebral visual impairment, and failure to thrive. Defining core phenotypic characteristics will improve precision diagnosis and treatment. [ABSTRACT FROM AUTHOR]

GTPases of the Rab family are important orchestrators of membrane trafficking, and their dysregulation has been linked to a variety of neuropathologies. In 2017, we established a causal link between RAB11A variants and developmental and epileptic encephalopathy. In this study, we expand the phenotype of RAB11A -associated neurodevelopmental disorder and explore genotype-phenotype correlations. We assessed 16 patients with pathogenic or likely pathogenic RAB11A variants, generally de novo , heterozygous missense variants. One individual had a homozygous nonsense variant, although concomitant with a pathogenic LAMA2 variant, which made their respective contributions to the phenotype difficult to discriminate. We reinforce the finding that certain RAB11A missense variants lead to intellectual disability and developmental delays. Other clinical features might include gait disturbances, hypotonia, magnetic resonance imaging abnormalities, visual anomalies, dysmorphisms, early adrenarche, and obesity. Epilepsy seems to be less common and linked to variants outside the binding sites. Individuals with variants in the binding sites seem to have a more multisystemic, nonepileptic phenotype. Similar to other Rab-related disorders, RAB11A -associated neurodevelopmental disorder can also impact gait, tonus, brain anatomy and physiology, vision, adrenarche, and body weight and structure. Epilepsy seems to affect the minority of patients with variants outside the binding sites. [ABSTRACT FROM AUTHOR]

Background: CDKL5 deficiency disorder (CDD) is an early-onset developmental and epileptic encephalopathy. While a subset of individuals is believed to experience comorbid behavioral disorders, none have reported well-defined affective disorders. Though there is a documented association between epilepsy and mood disorders, they may go undetected in the CDD population due to difficulty assessing mood in the presence of severe/profound intellectual disability and disease-related sleep dysregulation. We aimed to identify the clinical characteristics of an individual with CDD who presented with a mood disorder falling outside this expected behavioral phenotype., Case Presentation: We identified one 22-year-old female with CDD diagnosed with unspecified bipolar disorder at 18 years of age. Family history was noncontributory. At diagnosis, she had fluctuations in mood, characterized by periods of elated affect, increased energy and vocalizations, hypertonia, and insomnia lasting 3-4 days alternating with periods of depressed affect, irritability, hypotonia, and excessive sleep lasting for up to one month. She had experienced frequent mood swings and sleep dysregulation from early childhood, and by early adulthood the duration of "up" and "down" periods fell in the range specified in the DSM-5 bipolar disorder criteria. Trazodone and suvorexant did not alleviate sleep related symptoms. Her epilepsy was well controlled on lamotrigine monotherapy since early childhood. Though lamotrigine treatment has had no psychiatric benefit despite its known mood stabilizing properties, aripiprazole has been effective in reducing severity and frequency of fluctuations between hypomania and depression., Conclusions: While sleep and behavioral disorders fall within the expected phenotype for CDD, this is the first report of bipolar disorder. Careful attention to patterns of sleep and behavior that may indicate mood cycling in this population is required, particularly in the setting of limited communication and functional abilities.

Pathogenic variants in the cyclin-dependent kinase-like 5 (CDKL5) gene are associated with CDKL5 deficiency disorder (CDD), a severe X-linked developmental and epileptic encephalopathy. Deletions affecting the 5' untranslated region (UTR) of CDKL5, which involve the noncoding exon 1 and/or alternatively spliced first exons (exons 1a-e), are uncommonly reported. We describe genetic and phenotypic characteristics for 15 individuals with CDKL5 partial gene deletions affecting the 5' UTR. All individuals presented characteristic features of CDD, including medically refractory infantile-onset epilepsy, global developmental delay, and visual impairment. We performed RNA sequencing on fibroblast samples from three individuals with small deletions involving exons 1 and/or 1a/1b only. Results demonstrated reduced CDKL5 mRNA expression with no evidence of expression from alternatively spliced first exons. Our study broadens the genotypic spectrum for CDD by adding to existing evidence that deletions affecting the 5' UTR of the CDKL5 gene are associated with the disorder. We propose that smaller 5' UTR deletions may require additional molecular testing approaches such as RNA sequencing to determine pathogenicity., (© 2024 Wiley Periodicals LLC.)