Elizabeth I. Pierpont

Genotype differences in cognitive functioning in Noonan syndrome

Noonan syndrome (NS) is an autosomal‐dominant genetic disorder associated with highly variable features, including heart disease, short stature, minor facial anomalies and learning disabilities. Recent gene discoveries have laid the groundwork for exploring whether variability in the NS phenotype is related to differences at the genetic level. In this study, we examine the influence of both genotype and nongenotypic factors on cognitive functioning. Data are presented from 65 individuals with NS (ages 4–18) who were evaluated using standardized measures of intellectual functioning. The cohort included 33 individuals with PTPN11 mutations, 6 individuals with SOS1 mutations, 1 individual with a BRAF mutation and 25 participants with negative, incomplete or no genetic testing. Results indicate that genotype differences may account for some of the variation in cognitive ability in NS. Whereas cognitive impairments were common among individuals with PTPN11 mutations and those with unknown mutations, all of the individuals with SOS1 mutations exhibited verbal and nonverbal cognitive skills in the average range or higher. Participants with N308D and N308S mutations in PTPN11 also showed no (or mild) cognitive delays. Additional influences such as hearing loss, motor dexterity and parental education levels accounted for significant variability in cognitive outcomes. Severity of cardiac disease was not related to cognitive functioning. Our results suggest that some NS‐causing mutations have a more marked impact on cognitive skills than others.

Cardio-facio-cutaneous syndrome: clinical features, diagnosis, and management guidelines.

Cardio-facio-cutaneous syndrome (CFC) is one of the RASopathies that bears many clinical features in common with the other syndromes in this group, most notably Noonan syndrome and Costello syndrome. CFC is genetically heterogeneous and caused by gene mutations in the Ras/mitogen-activated protein kinase pathway. The major features of CFC include characteristic craniofacial dysmorphology, congenital heart disease, dermatologic abnormalities, growth retardation, and intellectual disability. It is essential that this condition be differentiated from other RASopathies, as a correct diagnosis is important for appropriate medical management and determining recurrence risk. Children and adults with CFC require multidisciplinary care from specialists, and the need for comprehensive management has been apparent to families and health care professionals caring for affected individuals. To address this need, CFC International, a nonprofit family support organization that provides a forum for information, support, and facilitation of research in basic medical and social issues affecting individuals with CFC, organized a consensus conference. Experts in multiple medical specialties provided clinical management guidelines for pediatricians and other care providers. These guidelines will assist in an accurate diagnosis of individuals with CFC, provide best practice recommendations, and facilitate long-term medical care.

Effects of Germline Mutations in the Ras/MAPK Signaling Pathway on Adaptive Behavior: Cardiofaciocutaneous Syndrome and Noonan Syndrome

Cardiofaciocutaneous syndrome (CFC) and Noonan syndrome (NS) are two phenotypically overlapping genetic disorders whose underlying molecular etiologies affect a common signaling pathway. Mutations in the BRAF, MEK1, and MEK2 genes cause most cases of CFC and mutations in PTPN11, SOS1, KRAS, and RAF1 typically cause NS. Although both syndromes are associated with developmental delays of varying severity, the extent to which the behavioral profiles differ may shed light on the different roles these respective genes play in development of skills necessary for everyday functioning. In this study, profiles of adaptive behavior of individuals with CFC and NS who had confirmed pathogenic mutations in Ras/mitogen‐activated protein kinase (MAPK) pathway genes were investigated. Patterns of strengths and weaknesses, age‐related differences, and risk factors for difficulties in adaptive skills were assessed. Although genes acting more downstream in the Ras/MAPK pathway were associated with more difficulties in adaptive functioning than genes more upstream in the pathway, several inconsistencies highlight the wide spectrum of possible developmental courses in CFC and NS. Along with clinical and genetic factors, variables such as chronological age, gestational age at birth, and parental education levels accounted for significant variance in adaptive skills. Results indicate that there is wide heterogeneity in adaptive functioning in CFC and NS, but that these abilities are correlated to some extent with the specific disease‐causing genes.

Attention skills and executive functioning in children with Noonan syndrome and their unaffected siblings

Emerging research indicates that gene mutations within the RAS‐MAPK signaling cascade, which cause Noonan syndrome and related disorders, affect neurophysiologic activity in brain regions underlying attention and executive functions. The present study examined whether children with Noonan syndrome are at heightened risk for symptoms of attention‐deficit–hyperactivity disorder (ADHD) and executive dysfunction relative to an unaffected sibling comparison group, and investigated three key aspects of behavioral attention: auditory attention, sustained attention, and response inhibition.

Learning and memory in children with Noonan syndrome.

Genetic syndromes resulting from molecular alterations of the RAS–MAPK signaling cascade have become the focus of heightened interest among behavioral scientists due to discoveries that proteins within this pathway play an important role in memory formation and consolidation. Individuals with Noonan syndrome (NS), caused by germline mutations in the RAS–MAPK pathway, exhibit wide variability in cognitive and memory skills. The current study aimed to characterize memory deficits that occur in some affected individuals as a key step toward understanding the neurocognitive effects of dysregulated Ras signaling. Learning and memory skills were assessed among 29 children and adolescents with NS using the Wide Range Assessment of Memory and Learning, Second Edition. Performance across subdomains (verbal memory, visual memory and working memory) was compared, as well as the effect of response type (free recall vs. recognition). For immediate memory, children with NS performed significantly better on verbal memory tasks than on visual memory or working memory tasks. For delayed memory, verbal free recall tasks that depend heavily on prefrontal‐hippocampal networks were more challenging than recognition tasks that rely on more distributed temporal cortical regions. Additionally, verbal information presented in context was more easily retained than that presented in a rote format. The current study contributes to our knowledge of the effects of dysregulated RAS–MAPK signaling on the brain and behavior. Continued research on neurocognitive skills in NS has the potential to generate a novel conceptualization of how learning disabilities can arise from altered molecular processes within a specific biological pathway.

Neurocognitive trajectory of boys who received a hematopoietic stem cell transplant at an early stage of childhood cerebral adrenoleukodystrophy

Importance Untreated childhood cerebral adrenoleukodystrophy (cALD) is a fatal disease associated with progressive cerebral demyelination and rapid, devastating neurologic decline. The standard of care to enhance long-term survival and stabilize cerebral disease is a hematopoietic stem cell transplant (HSCT). Neurologic outcomes are better when HSCT occurs at an earlier stage of cALD, yet there is limited understanding of the neurocognitive trajectory of patients who undergo HSCT. Objectives To characterize neurocognitive outcomes of boys with cALD and early-stage cerebral disease who were treated with an allogeneic HSCT and to identify disease- and treatment-related factors associated with long-term functioning. Design, Setting, and Participants Baseline and follow-up neurocognitive test performance was analyzed for all boys with cALD who received an HSCT at the University of Minnesota between January 1, 1991, and October 20, 2014, and who had a pretransplant magnetic resonance imaging (MRI) severity score of less than 10 (scale range, 0-34; higher scores indicate greater severity). Main Outcomes and Measures Longitudinal neurocognitive test performance in 4 domains (verbal comprehension, perceptual [visual] reasoning, working memory, and processing speed) were the primary outcome measures. Secondary analysis at the most recent evaluation also included measures of sustained attention, verbal memory, visual-motor integration, and fine motor function. Results Among the 62 boys in this study (mean [SD] age at transplant, 8.37 [2.80] years; range, 4-16 years), there was a significant association of pretransplant MRI severity and baseline verbal comprehension (r = –0.340; P = .008), perceptual reasoning (r = –0.419; P = .001), and processing speed (r = –0.285; P = .03) scores. Higher pretransplant MRI severity scores were also associated with a steeper decline in neurocognitive functioning during the 5-year follow-up period. Twenty-two of 33 patients (67%) with available long-term follow-up neurocognitive testing had severe impairment in at least 1 neurocognitive domain at the most recent evaluation. Conclusions and Relevance Boys with cALD who have greater than minimal cerebral disease detected on MRI scans at the time of an HSCT are at risk for severe, persistent neurocognitive deficits. These findings motivate further exploration of methods of detecting cerebral disease prior to development of lesions observable on MRI scans, an endeavor that may be facilitated by newborn screening for adrenoleukodystrophy. These findings may serve a benchmark role in evaluating the efficacy of novel interventions for cALD.

Behavioral functioning in cardiofaciocutaneous syndrome: Risk factors and impact on parenting experience

The present study is an investigation of behavioral functioning in children with cardiofaciocutaneous syndrome (CFC). CFC is a rare single‐gene disorder associated with cardiac disease, characteristic skin and facial features, intellectual disability, and neurological complications such as seizures and structural brain anomalies. Emotional and behavioral features of CFC have not been systematically investigated. We aimed to identify key variables that contribute to psychopathology during childhood and adolescence, and to examine the impact of challenging behaviors on the caregiving experience. Parents of 34 children and adolescents with CFC completed standardized broadband measures of child emotional and behavioral functioning, as well as measures of sensory modulation, functional communication, and caregiver stress. Results indicate that children with CFC syndrome are at heightened risk for psychopathology, with attention problems, social difficulties, and unusual behaviors (e.g., obsessive thoughts, strange behaviors, repetitive acts) found to be especially prevalent. Behavioral challenges in children with CFC syndrome were significantly associated with a history of obstetric complications and with problems modulating sensory information. With regard to the impact of child neurocognitive and behavioral issues on the caregiving experience, parent self‐reported stress was significantly higher among parents of children who engaged in more problem behaviors, and lower among parents whose children could communicate effectively with others. Results of this study suggest avenues to help families cope with CFC‐related stressors and enhance overall functioning. In particular, this study highlights the need for educational and treatment interventions aimed at addressing sensory needs, increasing functional communication, and identifying and managing challenging behaviors.

Variability in clinical and neuropsychological features of individuals with MAP2K1 mutations

Mutations in MAP2K1, a gene expressed within the RAS‐mitogen activated protein kinase (RAS/MAPK) pathway, are generally associated with the clinical phenotype of cardiofaciocutaneous syndrome. Here we describe two male patients (ages 16 and 20 years) with mutations in MAP2K1 and heterogeneous clinical presentations. Both young men had short stature, some facial features suggesting a RASopathy and minimal cardiac involvement. Detailed medical and neuropsychological findings are presented alongside a comprehensive review of features of patients with MAP2K1 mutations reported in the literature. Published studies have indicated that cognitive functioning of individuals with MAP2K1 mutations can range from severe intellectual disability to mildly below average. Neither of the individuals presented here had severe intellectual disability, and one had intellectual functioning within the average range. Neurodevelopmental concerns that were common among our two patients included fine motor difficulties, slow processing speed, reduced attention span, learning disabilities, and diminished energy/alertness. Taken together, our findings demonstrate that mutations in MAP2K1, which are frequently associated with neurological complications and intellectual disability, can be associated with a milder clinical and neurocognitive profile more typical of individuals with Noonan syndrome. Variability of expression may arise from a complex interplay between RAS/MAPK pathway genotype, epigenetics, medical and obstetric factors, and environmental influences.

The Arizona cognitive test battery for down syndrome: Test-retest reliability & practice effects

A multisite study investigated the test-retest reliability and practice effects of a battery of assessments to measure neurocognitive function in individuals with Down syndrome (DS). The study aimed to establish the appropriateness of these measures as potential endpoints for clinical trials. Neurocognitive tasks and parent report measures comprising the Arizona Cognitive Test Battery (ACTB) were administered to 54 young participants with DS (7-20 years of age) with mild to moderate levels of intellectual disability in an initial baseline evaluation and a follow-up assessment 3 months later. Although revisions to ACTB measures are indicated, results demonstrate adequate levels of reliability and resistance to practice effects for some measures. The ACTB offers viable options for repeated testing of memory, motor planning, behavioral regulation, and attention. Alternative measures of executive functioning are required.