A Qualitative Study to Characterize the Humanistic Burden of Kabuki Syndrome in the United States and Canada

Understanding the patient experience of Classic Galactosemia in pediatric and adult patients: increased disease burden, challenges with daily living, and how they evolve over time

BACKGROUND

Classic Galactosemia (CG) is a rare, autosomal recessive condition. Newborn screening and a timely galactose-restricted diet can resolve acute symptoms and decrease fatalities, but significant chronic, progressive morbidities remain and significantly impact daily life. The objective of this study was to better understand the burden of disease in children and adults with CGs and describe how morbidities evolve over time.

METHODS

A total of 49 individuals with CG from the United States (US) were included in the qualitative surveys (13 adults [9 self-reported] and 36 pediatric patients). Fifteen follow-up interviews were conducted with 5 adults and 10 caregivers, discussing 17 individuals with CG overall (2 caregivers each discussed 2 children).

RESULTS

Qualitative survey and interview data demonstrated the substantial burden of CG. Difficulties in a wide range of functions were experienced, which included: speech articulation; language and communication; cognition, memory and learning; emotions; and social interactions. Most difficulties appeared in childhood and persisted or worsened with age. Most adults did not live independently. Others lived semi-independently and experienced many daily challenges and required support. Caregivers also described the burden of caring for someone with CG and spoke about the impact this has on their day-to-day life, work, and relationships.

CONCLUSIONS

These findings demonstrate the pronounced and persistent burden of disease encountered by individuals with CG, and that the condition has a significant impact on the quality of life of caregivers.

Epigenetics of cognition and behavior: insights from Mendelian disorders of epigenetic machinery

Epigenetics, one mechanism by which gene expression can change without any changes to the DNA sequence, was described nearly a century ago. However, the importance of epigenetic processes to neurodevelopment and higher order neurological functions like cognition and behavior is only now being realized. A group of disorders known as the Mendelian disorders of the epigenetic machinery are caused by the altered function of epigenetic machinery proteins, which consequently affects downstream expression of many genes. These disorders almost universally have cognitive dysfunction and behavioral issues as core features. Here, we review what is known about the neurodevelopmental phenotypes of some key examples of these disorders divided into categories based on the underlying function of the affected protein. Understanding these Mendelian disorders of the epigenetic machinery can illuminate the role of epigenetic regulation in typical brain function and can lead to future therapies and better management for a host of neurodevelopmental and neuropsychological disorders.

Neurobehavioral phenotype of Kabuki syndrome: Anxiety is a common feature

Kabuki syndrome (KS) is a Mendelian Disorder of the Epigenetic Machinery (MDEM) caused by loss of function variants in either of two genes involved in the regulation of histone methylation, KMT2D (34–76%) or KDM6A (9–13%). Previously, representative neurobehavioral deficits of KS were recapitulated in a mouse model, emphasizing the role of KMT2D in brain development, specifically in ongoing hippocampal neurogenesis in the granule cell layer of the dentate gyrus. Interestingly, anxiety, a phenotype that has a known association with decreased hippocampal neurogenesis, has been anecdotally reported in individuals with KS. In this study, anxiety and behavior were assessed in a cohort of 60 individuals with molecularly confirmed KS and 25 unaffected biological siblings, via questionnaires (SCARED/GAS-ID and CBCL/ABCL). Participant age ranged from 4 to 43 years old, with 88.3% of participants having a pathogenic variant in KMT2D, and the rest having variants in KDM6A. In addition, data was collected on adaptive function and positive affect/quality of life in participants with KS using appropriate online surveys including ABAS-III and PROMIS Positive Affect. Survey scores were compared within the KS participants across age groups and between KS participants and their unaffected siblings. We found that children with KS have significantly higher anxiety scores and total behavior problem scores than their unaffected siblings (p = 0.0225, p < 0.0001). Moreover, a large proportion of affected individuals (22.2% of children and 60.0% of adults) surpassed the established threshold for anxiety; this may even be an underestimate given many patients are already treated for anxiety. In this sample, anxiety levels did not correlate with level of cognitive or adaptive function in any KS participants, but negatively correlated with positive affect in children with KS (p = 0.0005). These findings indicate that anxiety is a common neurobehavioral feature of KS. Providers should therefore carefully screen individuals with KS for anxiety as well as other behavioral issues in order to allow for prompt intervention. Neurobehavioral anxiety measures may also prove to be important outcome measures for clinical trials in KS.

From Genotype to Phenotype-A Review of Kabuki Syndrome

Kabuki syndrome (KS) is a rare neuro-developmental disorder caused by variants in genes of histone modification, including KMT2D and KDM6A. This review assesses our current understanding of KS, which was originally named Niikawa-Kuroki syndrome, and aims to guide surveillance and medical care of affected individuals as well as identify gaps in knowledge and unmet patient needs. Ovid MEDLINE and EMBASE databases were searched from 1981 to 2021 to identify reports related to genotype and systems-based phenotype characterization of KS. A total of 2418 articles were retrieved, and 152 were included in this review, representing a total of 1369 individuals with KS. Genotype, phenotype, and the developmental and behavioral profile of KS are reviewed. There is a continuous clinical phenotype spectrum associated with KS with notable variability between affected individuals and an emerging genotype-phenotype correlation. The observed clinical variability may be attributable to differences in genotypes and/or unknown genetic and epigenetic factors. Clinical management is symptom oriented, fragmented, and lacks established clinical care standards. Additional research should focus on enhancing understanding of the burden of illness, the impact on quality of life, the adult phenotype, life expectancy and development of standard-of-care guidelines.