Down syndrome (DS) is the most commonly identifiable genetic form of intellectual disability. Individuals with DS have considerable deficits in intellectual functioning (i.e., low intellectual quotient, delayed learning and/or impaired language development) and adaptive behavior. Previous pharmacological studies in this population have been limited by a lack of appropriate endpoints that accurately measured change in cognitive and functional abilities. Therefore, the current longitudinal observational study assessed the suitability and reliability of existing cognitive scales to determine which tools would be the most effective in future interventional clinical studies. Subtests of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Cambridge Neuropsychological Test Automated Battery (CANTAB), and Clinical Evaluation of Language Fundamentals-Preschool-2 (CELF-P-2), and the Observer Memory Questionnaire-Parent Form (OMQ-PF), Behavior Rating Inventory of Executive Function®–Preschool Version (BRIEF-P) and Leiter International Performance Scale-Revised were assessed. The results reported here have contributed to the optimization of trial design and endpoint selection for the Phase 2 study of a new selective negative allosteric modulator of the GABAA receptor α5-subtype (Basmisanil), and can be applied to other studies in the DS population.

Interferon regulatory factor 2 binding protein-like (IRF2BPL) encodes a member of the IRF2BP family of transcriptional regulators. Currently the biological function of this gene is obscure, and the gene has not been associated with a Mendelian disease. Here we describe seven individuals who carry damaging heterozygous variants in IRF2BPL and are affected with neurological symptoms. Five individuals who carry IRF2BPL nonsense variants resulting in a premature stop codon display severe neurodevelopmental regression, hypotonia, progressive ataxia, seizures, and a lack of coordination. Two additional individuals, both with missense variants, display global developmental delay and seizures and a relatively milder phenotype than those with nonsense alleles. The IRF2BPL bioinformatics signature based on population genomics is consistent with a gene that is intolerant to variation. We show that the fruit-fly IRF2BPL ortholog, called pits (protein interacting with Ttk69 and Sin3A), is broadly detected, including in the nervous system. Complete loss of pits is lethal early in development, whereas partial knockdown with RNA interference in neurons leads to neurodegeneration, revealing a requirement for this gene in proper neuronal function and maintenance. The identified IRF2BPL nonsense variants behave as severe loss-of-function alleles in this model organism, and ectopic expression of the missense variants leads to a range of phenotypes. Taken together, our results show that IRF2BPL and pits are required in the nervous system in humans and flies, and their loss leads to a range of neurological phenotypes in both species.

We conducted two multicenter studies on adaptive trajectories and profiles in males with fragile X syndrome. Study 1 longitudinally assessed 29 males ages 1-20 years using age-equivalent scores from the Vineland Adaptive Behavior Scales. Fragile X boys ages 1-10 years showed significant gains in adaptive skills from first to second testing; males ages 11-20 years were stable in their adaptive development. Study 2 cross-sectionally examined 132 males ages 1-20 years. Significant age-related gains were found in boys ages 1-10, particularly in preschool children. Subjects ages 11-20 showed increased variability and nonsignificant relations between age and adaptive skills. Preliminary findings from 26 young adults with fragile X syndrome ages 21-40 years showed stable age-equivalent adaptive scores during these years. Relative strengths in daily living skills and weaknesses in communication were only evident among older subjects. Significant relations were found between adaptive behavior standard scores and IQ; these two scores also showed age-related declines that likely parallel one another. Findings are related to adaptive features in other genetic syndromes, and to directions for future adaptive behavior research.

Little is known about how and what genetic risk information parents communicate to their children and even less is known about what children hear and remember. To address this void, we explored how genetic risk information was learned, what information was given and who was primarily provided information to adolescent girls and young adult women in families with fragile X syndrome. We explored three levels of risk knowledge, learning that fragile X syndrome was an inherited disorder, that they could be a carrier, and for those who had been tested, actual carrier status. These data were collected as part of a study that also explored adolescent self concept and age preferences about when to inform about genetic risk. Those findings have been presented separately. The purpose of this paper is to present the communication data. Using a multi-group cross-sectional design this study focused on girls ages 14–25 years from families previously diagnosed with fragile X syndrome, who knew they were carriers (n = 20), noncarriers (n = 18), or 3) at-risk to be carriers (n = 15). For all three stages of information the majority of the study participants were informed by a family member. We identified three different communication styles, open, sought information, and indirect. The content of the remembered conversations varied based on the stage of genetic risk information being disclosed as well as the girls’ knowledge of her own carrier status. Girls who had been tested and knew their actual carrier status were more likely to report an open communication pattern than girls who knew only that they were at-risk.

The purpose of this study is to describe the interplay of adolescent girls' self-concept, coping behaviors, and adjustment associated with knowledge of genetic risk for fragile X syndrome. We will report here findings on self concept. Using a multi-group cross-sectional design this study focused on girls ages 14-25 years from families previously diagnosed with fragile X syndrome, who knew they were 1) carriers (n = 20; mean age 18.35 years s.d. 2.5), or 2) noncarriers (n =18; mean age 17.78 years s.d. 2.69), or 3) at-risk to be carriers (n = 15; mean age 17.87 s.d. 3.18). The girls completed the Tennessee Self Concept Scale (TSCS:2), a visual analog scale, and a guided interview. Total and all subscale scores on the TSCS:2 were in the normal range for all three groups. However, threats to self concept were found in personal self (physical self, genetic identity, and parental role), social self, and family self (family genetic identity) as they specifically related to the meaning of genetic information and varied based on risk status. Our findings suggest that risk information itself is threatening and for some girls, may be as threatening as learning one is a carrier. Certainty related to genetic risk status appears to make a positive difference for some girls by allowing them the opportunity to face the challenge of their genetic risk status and to begin to consider the meaning of this information.