A case of Bainbridge-Ropers syndrome with breath holding spells and intractable epilepsy: challenges in diagnosis and management

Four heterozygous de novo variants in ASXL3 identified with Bainbridge-Ropers syndrome and further dissecting published genotype-phenotype spectrum

Bainbridge-Ropers syndrome (BRPS) is a recently described neurodevelopmental genetic disorder associated with de novo truncating variants in additional sex combs like 3 (ASXL3) on chromosome 18q12.1. Trio-based exome sequencing was conducted on patients admitted to the Children's Hospital Affiliated to Shandong University and diagnosed with unexplained intellectual disabilities or developmental delay between June 2022 and January 2024. De novo truncation of ASXL3 was identified in four patients, and the pathogenic variants and their de novo status were validated using Sanger sequencing. Comprehensive clinical phenotype-genotype information of all previously reported patients with BRPS was collected and summarized. The common clinical manifestations observed in the four patients included language and intellectual disabilities or psychomotor retardation. Genetic analysis revealed that patient 1 carried a de novo heterozygous variant, c.1667_1668del (p.Thr556Arpfs*3), whereas patient 2 had a novel heterozygous frameshift variant of ASXL3, c.3324del (p.Lys1109Serfs*34). These two variants have not been documented to date. Additionally, patients 3 and 4 exhibited a de novo variant, c.4678C > T (p.Arg1560Ter). Based on the combined assessment of clinical phenotypes and genetic testing results, it was postulated that all four children presented with BRPS syndrome caused by pathogenic variations in ASXL3. The present study complements the range of ASXL3 mutational and phenotypic spectra in the population, highlighting subtle distinctions in clinical manifestations between Chinese patients and other racial groups. The reporting of additional cases will contribute to further elucidating the function of ASXL3 and establishing a solid foundation for clinical diagnosis and treatment.

Bainbridge-Ropers Syndrome in a Texan Boy: A Case Report and Review of the Literature

Bainbridge-Ropers syndrome (BRPS) or additional sex combs-like 3 (ASXL3)-related disorder is a neurodevelopmental disorder caused by a de novo missense mutation in the ASXL3 gene found on chromosome 18. The number of BRPS cases recorded to date is less than 100. In this report, a six-year-old Texan boy with global developmental delay, aggressive behavior, insomnia, microcephaly, strabismus, facial dysmorphic features, vesicoureteral reflux (VUR), bilateral congenital renal dysplasia, gastroesophageal reflux disease (GERD), hypotonia, failure to thrive, dysphagia, and status post-gastrostomy tube was referred to Children's Health in Dallas for evaluation. The patient shares a chromosomal abnormality with his father that did not explain his clinical findings. Therefore, further tests were indicated and a whole-exome gene sequencing revealed a de novo pathogenic heterozygous mutation in the ASXL3 gene in chromosome 18q12.1 associated with autosomal dominant BRPS. To our knowledge, this is the first case of BRPS with bilateral congenital renal dysplasia and may be correlated to the presence of the ASXL3 gene in renal tissue. This discovery provides significant new information about this condition that might be essential for comprehending it.

ASXL3 De Novo Variant-Related Neurodevelopmental Disorder Presenting as Dystonic Cerebral Palsy

ASXL3 loss-of-function variants represent a well-established cause of Bainbridge-Ropers syndrome, a syndromic neurodevelopmental disorder with intellectual and motor disabilities. Although a recent large-scale genomics-based study has suggested an association between ASXL3 variation and cerebral palsy, there have been no detailed case descriptions. We report, here, a female individual with a de novo pathogenic c.1210C > T, p.Gln404* nonsense variant in ASXL3, identified within the frame of an ongoing research project applying trio whole-exome sequencing to the diagnosis of dystonic cerebral palsy. The patient presented with a mixture of infantile-onset limb/trunk dystonic postures and secondarily evolving distal spastic contractures, in addition to more typical features of ASXL3-related diseases such as severe feeding issues, intellectual disability, speech impairment, and facial dysmorphic abnormalities. Our case study confirms a role for ASXL3 pathogenic variants in the etiology of cerebral-palsy phenotypes and indicates that dystonic features can be part of the clinical spectrum in Bainbridge-Ropers syndrome. ASXL3 should be added to target-gene lists used for molecular evaluation of cerebral palsy.

Fenfluramine: A Review of Pharmacology, Clinical Efficacy, and Safety in Epilepsy

Despite the availability of more than 30 antiseizure medications (ASMs), the proportion of patients who remain refractory to ASMs remains static. Refractory seizures are almost universal in patients with epileptic encephalopathies. Since many of these patients are not candidates for curative surgery, there is always a need for newer ASMs with better efficacy and safety profile. Recently, the anti-obesity medication fenfluramine (FFA) has been successfully repurposed, and various regulatory agencies approved it for seizures associated with Dravet and Lennox–Gastaut syndromes. However, there is a limited in-depth critical review of FFA to facilitate its optimal use in a clinical context. This narrative review discusses and summarizes the antiseizure mechanism of action of FFA, clinical pharmacology, and clinical studies related to epilepsy, focusing on efficacy and adverse effects.