Genotype-phenotype correlations with autism spectrum disorder-related traits in noonan syndrome and noonan syndrome with multiple lentigines: a cross-sectional study.

Researchers studied behavior patterns in children with Noonan Syndrome, a genetic condition that can affect development. They found that children with certain genetic types of Noonan Syndrome showed more autism-like behaviors, social difficulties, and emotional problems compared to typically developing children. The study also discovered that a specific protein activity level could predict which children might have more repetitive behaviors. This helps explain why some children with Noonan Syndrome have different behavioral challenges than others.

This cross-sectional study examined behavioral phenotypes in 121 individuals with Noonan Syndrome (NS) and 7 with Noonan Syndrome with Multiple Lentigines (NSML), comparing them to 71 typically developing controls. Using standardized questionnaires (SRS-2, CBCL), researchers found that individuals with PTPN11-associated NS, NSML, and SOS1-associated NS showed clinically elevated autism spectrum disorder (ASD)-related behaviors, poorer social functioning, and heightened emotional problems compared to controls. PTPN11-associated NS and NSML groups demonstrated greater ASD-related challenges than RAF1 variants. Biochemical analysis revealed that higher SHP2 protein activation in PTPN11 variants corresponded to a 64% increased likelihood of severe restricted and repetitive behaviors, suggesting specific genotype-phenotype relationships within the RAS-MAPK pathway.

Results support genetic variant-specific behavioral screening and intervention planning for Noonan Syndrome. SHP2 activation levels may serve as biomarkers for predicting restricted/repetitive behavior severity in PTPN11 variants. Findings suggest need for ASD-informed assessment protocols and potentially targeted treatments based on specific genetic variants in clinical practice.

Small sample sizes for rarer genetic variants led to unequal group comparisons, with PTPN11 variants comprising most participants. Cross-sectional design limits understanding of behavioral development over time. Findings may not generalize to all Noonan Syndrome variants due to sampling constraints.

Noonan syndrome (NS) and Noonan syndrome with multiple lentigines (NSML) are neurodevelopmental conditions caused by genetic variants leading to upregulated signaling in the RAS-MAPK pathway. While previous research has focused on genetic variability in cognitive and cardiac phenotypes, behavioral phenotypes, and their correlations across genetic variants and within the PTPN11 gene remain poorly characterized. This study included 121 individuals with NS (PTPN11: 88, SOS1: 18, RAF1: 6, KRAS: 2, RIT1: 3, NRAS: 2, LZTR1: 2, SOS2: 1) and seven individuals with NSML (PTPN11), compared to age- and sex-matched typically developing (TD) (N = 71). Behavioral questionnaires assessed social responsiveness and ASD-related traits (using SRS-2), and emotional problems (using CBCL) to identify genetic variant-specific behavioral profiles.

Biochemical profiling of SHP2 activity in PTPN11-associated NS variants examined genotype-phenotype relationships. Compared to TD individuals, those with PTPN11-associated NS, NSML, and SOS1-associated NS exhibited clinically elevated scores, indicating increased ASD-related behaviors, poorer social functioning, and heightened emotional problems. Genetic variant comparisons revealed that individuals with PTPN11-associated NS and NSML exhibited greater ASD-related challenges than those with RAF1. Individuals with NSML exhibit elevated attention problems compared to all other genetic groups.

Logistic regression results suggested each one-unit increase in SHP2 fold activation for PTPN11-associated NS corresponded to a 64% higher likelihood of markedly elevated restricted and repetitive behaviors, suggesting genotype-phenotype links. Small sample sizes for rarer variants, leading to unequal group sizes across subgroups, with PTPN11 variants comprising most of the NS group. Future research should address these sampling constraints and conduct functional studies to clarify variant impacts. Longitudinal assessments could elucidate behavioral phenotype trajectories.

This study underscores the importance of genetic variant-specific research to understand unique behavioral phenotypes in NS and NSML. Our findings indicate a higher risk for ASD-related symptoms in PTPN11-associated NS and NSML compared to other variants. Additionally, individuals with PTPN11-associated NS and higher SHP2 fold activation exhibited greater impairments in restricted and repetitive behaviors, suggesting SHP2 activation variations may contribute to phenotypic variability. By linking ASD-related symptoms to biochemical predictors in PTPN11-associated NS, this study may inform future targeted treatment approaches.