This study reports a previously unrecognized heterozygous MYCN missense variant, c.454G>A (p.Ala152Thr), identified in a child and two affected relatives with clinical findings consistent with Feingold syndrome type 1, an autosomal dominant developmental disorder most commonly caused by loss-of-function variants in MYCN. The proband presented with cleft palate, craniofacial dysmorphism, feeding difficulties, hypotonia, and characteristic digital anomalies. Similar features were observed in the father and sibling. Clinical exome sequencing revealed the novel MYCN variant, which was confirmed by Sanger sequencing and demonstrated co-segregation with the phenotype. Although most pathogenic MYCN variants leading to FS1 truncate the protein, this missense change lies within the N-terminal transactivation domain, a region involved in transcriptional regulation and protein stability. The physicochemical alteration introduced at residue Ala152 may plausibly affect MYCN function, consistent with haploinsufficiency as the established disease mechanism. According to the 2024 ACGS Best Practice Guidelines, the variant is classified as a Variant of Uncertain Significance leaning toward pathogenicity (VUS-warm). This report expands the mutational spectrum of MYCN, supports the potential clinical relevance of N-terminal missense variation in MYCN, and highlights intrafamilial phenotypic variability in FS1.

This study reports a previously unreported heterozygous MYCN missense variant, c.454G>A (p.Ala152Thr), identified in a child and two affected relatives, with clinical findings consistent with Feingold syndrome type 1, an autosomal dominant developmental disorder most commonly caused by loss-of-function variants in MYCN. The proband presented with a cleft palate, craniofacial dysmorphism, feeding difficulties, hypotonia, and characteristic digital anomalies. Similar features were observed in the father and sibling. Clinical exome sequencing revealed the novel MYCN variant, which was confirmed by Sanger sequencing and demonstrated co-segregation with the phenotype. Although most pathogenic MYCN variants leading to FS1 truncate the protein, this missense change lies within the N-terminal transactivation domain, a region involved in transcriptional regulation and protein stability. The physicochemical alteration introduced at residue Ala152 may plausibly affect MYCN function, consistent with haploinsufficiency as the established disease mechanism. According to the 2024 ACGS Best Practice Guidelines, the variant was classified as a variant of uncertain significance leaning toward pathogenicity. This report expands the mutational spectrum of MYCN, supports the potential clinical relevance of N-terminal missense variation in MYCN, and highlights intrafamilial phenotypic variability in FS1.

Background/Objectives: Pharmacogenomics (PGx) enables personalized therapy by identifying genetic variants that influence drug response. Despite the advantages of next-generation sequencing (NGS), few clinically validated, guideline-aligned panels comprehensively detect common, rare, and structurally complex pharmacogenetic variants. Methods: We developed and analytically validated Action PharmaKitDx, a targeted NGS panel covering 335 pharmacogenes, including all priority genes recommended by CPIC, DPWG, and CPNDS. Performance was assessed using Coriell HapMap and GeT-RM reference materials across multiple library preparation workflows and Illumina platforms. Clinical feasibility was evaluated in 41 patient samples from diverse specialties. Results were compared with established reference methods, including PCR-based assays, STR analysis, Sanger sequencing, and whole-exome sequencing. Results: More than 99% of target bases achieved ≥30× coverage. Analytical accuracy, sensitivity, specificity, and positive predictive value exceeded 99.3%, with repeatability and reproducibility >99.7%. Concordance with GeT-RM haplotypes reached 98% after star-allele harmonization. The panel accurately detected complex variants, including CYP2D6 copy-number changes and hybrid alleles. Full concordance with prior genotyping was observed in clinical samples. Beyond the initial testing indication, each sample harbored a mean of six actionable variants (range 2–10). Thirty-six rare (minor allele frequency <1%) potentially actionable variants were additionally identified. Conclusions: Action PharmaKitDx demonstrates high analytical performance and broad clinical applicability, supporting its implementation as a scalable solution for comprehensive pharmacogenetic testing and precision prescribing.

Background/Objectives: Pharmacogenomics (PGx) enables personalized therapy by identifying genetic variants that influence drug response. Despite the advantages of next-generation sequencing (NGS), few clinically validated, guideline-aligned panels comprehensively detect common, rare, and structurally complex pharmacogenetic variants. Methods: We developed and analytically validated Action PharmaKitDx, a targeted NGS panel covering 335 pharmacogenes, including all priority genes recommended by CPIC, DPWG, and CPNDS. Performance was assessed using Coriell HapMap and GeT-RM reference materials across multiple library preparation workflows and Illumina platforms. Clinical feasibility was evaluated in 41 patient samples from diverse specialties. Results were compared with established reference methods, including PCR-based assays, STR analysis, Sanger sequencing, and whole-exome sequencing. Results: Analytical validation: More than 99% of target bases achieved ≥30× coverage. Analytical accuracy, sensitivity, specificity, and positive predictive value exceeded 99.3%, with repeatability and reproducibility >99.7%. Concordance with GeT-RM haplotypes reached 98% after star-allele harmonization. The panel accurately detected complex variants, including CYP2D6 copy-number changes and hybrid alleles. Clinical validation: Full concordance with prior genotyping was observed in clinical samples. Beyond the initial testing indication, each sample harbored a mean of six actionable variants (range 2–10). Thirty-six rare (minor allele frequency <1%) potentially actionable variants were additionally identified. Conclusions: Action PharmaKitDx demonstrates high analytical performance and broad clinical applicability, supporting its implementation as a scalable solution for comprehensive pharmacogenetic testing and precision prescribing.