UNASSIGNED: With no family history, and an atypical phenotype, the clinical diagnosing of Noonan syndrome (NS) can be very difficult. The present case emphasized that generalized edema in neonates may be the potential first symptom of NS.
UNASSIGNED: Severe generalized edema is a rare pathological condition with high mortality in newborns, in particular the premature infants. It is characterized by the extensive subcutaneous tissue edema and the accumulation of fluid in neonatal body fluid compartments. The etiology and pathogenesis of hydrops in neonates are quite complex. Generally speaking, hydrops can be divided into immune hydrops and non-immune hydrops according to the etiology. It is still challenging in treating severe neonatal edema. In this study, we presented a preterm newborn with severe generalized edema after birth, which was finally diagnosed with Noonan syndrome (NS). The infant clinically manifested as severe generalized edema alone, without the involvement of multiple organ malformation. Generalized edema in neonates was probably the first symptom of NS. Therefore, differential diagnosis of NS is necessary for infants developing generalized edema.

Histiocytic sarcoma (HS) is a rare and highly aggressive cancer in humans and dogs. In dogs, it has a high prevalence in certain breeds, such as Bernese mountain dogs (BMDs) and flat-coated retrievers. Hemophagocytic histiocytic sarcoma (HHS) is a unique form of HS that presents with erythrophagocytosis. Due to its rareness, the study of HHS is very limited, and mutations in canine HHS patients have not been studied to date. In previous work, our research group identified two major PTPN11/SHP2 driver mutations, E76K and G503V, in HS in dogs. Here, we report additional mutations located in exon 3 of PTPN11/SHP2 in both HS and HHS cases, further supporting that this area is a mutational hotspot in dogs and that mutations in tumors and liquid biopsies should be evaluated utilizing comprehensive methods such as Sanger and NextGen sequencing. The overall prevalence of PTPN11/SHP2 mutations was 55.8% in HS and 46.2% in HHS. In addition, we identified mutations in KRAS, in about 3% of HS and 4% of HHS cases. These findings point to the shared molecular pathology of activation of the MAPK pathway in HS and HHS cases. We evaluated the efficacy of the highly specific MEK inhibitor, cobimetinib, in canine HS and HHS cell lines. We found that the IC50 values ranged from 74 to 372 nM, which are within the achievable and tolerable ranges for cobimetinib. This finding positions cobimetinib as a promising potential candidate for future canine clinical trials and enhances our understanding of the molecular defects in these challenging cancers.

Juvenile myelomonocytic leukemia (JMML), a clonal hematologic malignancy, originates from mutated hematopoietic stem cells (HSCs). The mechanism sustaining the persistence of mutant stem cells, leading to leukemia development, remains elusive. In this study, we conducted comprehensive examination of gene expression profiles, transcriptional factor regulons, and cell compositions/interactions throughout various stages of tumor cell development in Ptpn11 mutation-associated JMML. Our analyses revealed that leukemia-initiating Ptpn11 E76K/+ mutant stem cells exhibited de novo activation of the myeloid transcriptional program and aberrant developmental trajectories. These mutant stem cells displayed significantly elevated expression of innate immunity-associated anti-microbial peptides and pro-inflammatory proteins, particularly S100a9 and S100a8. Biological experiments confirmed that S100a9/S100a8 conferred a selective advantage to the leukemia-initiating cells through autocrine effects and facilitated immune evasion by recruiting and promoting immune suppressive myeloid-derived suppressor cells (MDSCs) in the microenvironment. Importantly, pharmacological inhibition of S100a9/S100a8 signaling effectively impeded leukemia development from Ptpn11 E76K/+ mutant stem cells. These findings collectively suggest that JMML tumor-initiating cells exploit evolutionarily conserved innate immune and inflammatory mechanisms to establish clonal dominance.

UNASSIGNED: Noonan syndrome (NS) and Noonan-like syndrome with loose anagen hair (NS/LAH) are neurodevelopmental syndromes resulting from germline mutations in genes that participate in the rat sarcoma/mitogen-activated protein kinases (RAS/MAPK) pathway. The aim of this retrospective study was to describe common and rare manifestations of NS and NS/LAH.
UNASSIGNED: We collected and analyzed clinical and genetic data from 25 patients with NS and NS/LAH.
UNASSIGNED: The patients\' median age was 6.3 years (range, 1-13 years), and the male-to-female ratio was 18:7. In total, 19 patients had NS caused by a mutation in PTPN11. Another causative gene was found in six patients, including two patients with a SHOC2 mutation, one patient with a KRAS mutation, one patient with an LZTR1 mutation, one patient with a BRAF mutation, and one patient with a PPP1CB mutation. Short stature was detected in 100% of the patients. This study provides an overview of the clinical features of NS, including unique facial features, short stature, congenital heart defects, and other manifestations. Notably, systemic lupus erythematosus (SLE) was found in two SHOC2-positive patients. One patient had a posterior urethral valve, which is very rare in NS patients.
UNASSIGNED: Our study identified several clinical features that were previously poorly related to NS, including SLE. We concluded that SHOC2-related NS is associated with a particularly high risk of SLE, which may have a significant impact on quality of life, and a posterior urethral valve is a novel phenotype. These findings could be helpful in enhancing the understanding of the clinical spectrum of NS.

UNASSIGNED: Congenital scoliosis and congenital anomalies of the kidney and urinary tract are distinct genetic disorders with differing clinical manifestations. Clinically, their coexistence is not rare, but the etiologies of these complex diseases remain largely unknown, especially their shared genetic basis.
UNASSIGNED: We sequenced the genomes of 40 individuals diagnosed with both CS and CAKUT, alongside 2,764 controls from a Chinese Han population cohort. Our analyses encompassed gene-based and pathway-based weighted rare variant association tests, complemented by copy number variant association analyses, aiming to unravel the shared genomic etiology underlying these congenital conditions.
UNASSIGNED: Gene-based analysis identified PTPN11 as a pivotal gene influencing both skeletal and urinary system development (P = 1.95E-21), participating in metabolic pathways, especially the MAPK/ERK pathway known to regulate skeletal and urinary system development. Pathway-based enrichment showed a significant signal in the MAPK/ERK pathway (P = 3E-04), reinforcing the potential role of PTPN11 and MAPK/ERK pathway in both conditions. Additionally, CNV analysis pinpointed IGFLR1 haploinsufficiency as a potential influential factor in the combined CS-CAKUT phenotypic spectrum.
UNASSIGNED: This study enriches our understanding of the intricate genomic interplay underlying congenital scoliosis and kidney and urinary tract anomalies, emphasizing the shared genetic foundations between these two disorders.

Multi-domain enzymes can be regulated by both inter-domain interactions and structural features intrinsic to the catalytic domain. The tyrosine phosphatase SHP2 is a quintessential example of a multi-domain protein that is regulated by inter-domain interactions. This enzyme has a protein tyrosine phosphatase (PTP) domain and two phosphotyrosine-recognition domains (N-SH2 and C-SH2) that regulate phosphatase activity through autoinhibitory interactions. SHP2 is canonically activated by phosphoprotein binding to the SH2 domains, which causes large inter-domain rearrangements, but autoinhibition can also be disrupted by disease-associated mutations. Many details of the SHP2 activation mechanism are still unclear, the physiologically-relevant active conformations remain elusive, and hundreds of human variants of SHP2 have not been functionally characterized. Here, we perform deep mutational scanning on both full-length SHP2 and its isolated PTP domain to examine mutational effects on inter-domain regulation and catalytic activity. Our experiments provide a comprehensive map of SHP2 mutational sensitivity, both in the presence and absence of inter-domain regulation. Coupled with molecular dynamics simulations, our investigation reveals novel structural features that govern the stability of the autoinhibited and active states of SHP2. Our analysis also identifies key residues beyond the SHP2 active site that control PTP domain dynamics and intrinsic catalytic activity. This work expands our understanding of SHP2 regulation and provides new insights into SHP2 pathogenicity.

RASopathies are a group that encompasses a spectrum of related disorders caused by mutations linked to the RAS/mitogen-activated protein kinase (RAS/MAPK) pathway, including neurofibromatosis type 1 (NF1), Noonan syndrome (NS), neurofibromatosis-Noonan syndrome (NFNS), Noonan syndrome with multiple lentigines (NSML). Neurofibromas, as a hallmark of NF1, are extremely rare in patients with other RASopathies. Here we present a case of a 39-year-old Chinese male displaying orbital neurofibromas and lumbosacral plexiform neurofibromas. Histopathology of a CT-guided biopsy of the mass revealed it to be a neurofibroma. The targeted sequencing analysis did not find any pathogenic sequence alteration in the NF1 or NF2 causative genes in blood lymphocytes and hypertrophic nerve tissue, and no additional signs of NF1 were detected, thereby not meeting the diagnostic criteria for NF1. However, we identified a heterozygous mutation (c.836A>G, p.Y279C) in the PTPN11 gene, which is one of the key components of the RAS-MAPK signaling pathway and is associated with NS, NFNS, and NSML. Nonetheless, a thorough examination did not reveal any signs of these syndromes in the patient. Consequently, it was inferred that this patient likely falls within the spectrum of the RASopathies. This represents a unique case manifesting as orbital and lumbosacral plexiform neurofibromas carrying a PTPN11 gene mutation, thereby broadening the phenotype spectrum of PTPN11 mutations. Our results also highlight the overlap between RASopathies. Neurofibromas should be considered indicative of a broader spectrum of disorders resulting from mutations in RASopathies other than NF1.

UNASSIGNED: Fibroblast growth factor receptor 1 (FGFR1) mutations have been associated with poorer prognoses in pediatric central nervous system tumor patients. A recent study highlighted a link between FGFR1 mutations and spontaneous intracranial hemorrhage (ICH), demonstrating that all patients with an FGFR1 alteration experienced hemorrhage at some point during their course of treatment.
UNASSIGNED: The current study examined 50 out of 67 pediatric patients with low-grade gliomas (LGGs) who had genomic testing between 2011 and 2022 at our institution to determine whether a correlation exists between FGFR1 mutations and spontaneous ICH.
UNASSIGNED: We found that of the 50 patients with genomic data, 7 (14%) experienced ICH, and an additional spontaneous hemorrhage was recorded; however, no genomic testing was performed for this case. Five of the seven patients (71.4%) had an FGFR1 modification. In our patient population, 6 expressed a detectable FGFR1 mutation (66.7% [4/6] had N546K alteration, 16.7% [1/6] FGFR1 exons duplication, and 16.7% [1/6] had a variant of unknown significance [VUS]). The patient with the FGFR1 VUS had no reported spontaneous hemorrhage. Statistical analysis found a significant association between FGFR1 and spontaneous intracranial hemorrhage (P-value = < .0001). In the patient population, all cases of PTPN11 alterations (n = 3) co-occurred with FGFR1 mutations.
UNASSIGNED: Our case series highlights this link between the FGFR1 mutation and spontaneous intracranial hemorrhage in pediatric LGGs.

Lesions of the semilunar valve and the aortic arch can occur either in isolation or as part of well-described clinical syndromes. The polygenic cause of calcific aortic valve disease will be discussed including the key role of NOTCH1 mutations. In addition, the complex trait of bicuspid aortic valve disease will be outlined, both in sporadic/familial cases and in the context of associated syndromes, such as Alagille, Williams, and Kabuki syndromes. Aortic arch abnormalities particularly coarctation of the aorta and interrupted aortic arch, including their association with syndromes such as Turner and 22q11 deletion, respectively, are also discussed. Finally, the genetic basis of congenital pulmonary valve stenosis is summarized, with particular note to Ras-/mitogen-activated protein kinase (Ras/MAPK) pathway syndromes and other less common associations, such as Holt-Oram syndrome.

Ventricular septal defects (VSDs) are recognized as one of the commonest congenital heart diseases (CHD), accounting for up to 40% of all cardiac malformations, and occur as isolated CHDs as well as together with other cardiac and extracardiac congenital malformations in individual patients and families. The genetic etiology of VSD is complex and extraordinarily heterogeneous. Chromosomal abnormalities such as aneuploidy and structural variations as well as rare point mutations in various genes have been reported to be associated with this cardiac defect. This includes both well-defined syndromes with known genetic cause (e.g., DiGeorge syndrome and Holt-Oram syndrome) and so far undefined syndromic forms characterized by unspecific symptoms. Mutations in genes encoding cardiac transcription factors (e.g., NKX2-5 and GATA4) and signaling molecules (e.g., CFC1) have been most frequently found in VSD cases. Moreover, new high-resolution methods such as comparative genomic hybridization enabled the discovery of a high number of different copy number variations, leading to gain or loss of chromosomal regions often containing multiple genes, in patients with VSD. In this chapter, we will describe the broad genetic heterogeneity observed in VSD patients considering recent advances in this field.