UNLABELLED: Noonan syndrome (NS) is a genetic condition presenting with typical facies, cardiac defects, short stature, variable developmental deficit, cryptorchidism, skeletal, and other abnormalities. Germline mutations in genes involved in the RAS/MAPK signaling have been discovered to underlie NS. Recently, missense mutations in RIT1 have been reported as causative for individuals with clinical signs of NS. We report on a 2.5-year-old boy with NS phenotype with a novel heterozygous change in the RIT1 gene. The patient was born prematurely from pregnancy monitored for polyhydramnios. At 7 months of age, non-immune neutropenia and splenomegaly have been observed. During the severe pneumonia at 10 months, significant progression of hepatosplenomegaly, leukopenia with monocytosis (15-29 %), and thrombocytopenia occurred. Bone marrow evaluation showed myeloid hyperplasia and monocytosis, suggestive of myeloproliferative syndrome. Clinical phenotype (facial dysmorphism, soft hair, short neck, broad chest, widely spaced nipples, mild pectus carinatum, deep palmar creases, unilateral cryptorchidism), and moderate pulmonary valve stenosis with mild psychomotor delay were indicative of NS. DNA analysis identified a de novo heterozygous variant c.69A >T, p.(Lys23Asn) in exon 2 of the RIT1 gene, presumed to be causative. CONCLUSION: We present a patient with a clinical suspicion of NS carrying a novel substitution in RIT1 and hematologic findings not being observed in RIT1 positive patients to date. Thus, the case broadens variability of hematologic symptoms in RIT1 positive NS individuals. WHAT IS KNOWN: • Noonan syndrome is a common genetically heterogeneous disorder of autosomal dominant inheritance characterized by craniofacial dysmorphism, short stature, congenital heart defects, variable cognitive deficit, and other anomalies. What is new: • We report on a 2.5-year-old male patient with clinical signs of NS and hematologic abnormalities, in whom a novel heterozygous substitution in RIT1 with probable pathogenicity was detected.

• Klíčová slova
• Leukopenia, Myeloproliferative, Noonan syndrome, RASopathies, RIT1,
• MeSH
• fenotyp MeSH
• heterozygot MeSH
• leukopenie diagnóza   genetika   MeSH
• lidé MeSH
• missense mutace MeSH
• myeloproliferativní poruchy diagnóza   genetika   MeSH
• Noonanové syndrom diagnóza   genetika   MeSH
• předškolní dítě MeSH
• Ras proteiny genetika   MeSH
• těhotenství MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• Ras proteiny MeSH
• RIT1 protein, human MeSH Prohlížeč

PURPOSE: Noonan syndrome (NS) is an autosomal-dominant disorder characterized by craniofacial dysmorphism, growth retardation, cardiac abnormalities, and learning difficulties. It belongs to the RASopathies, which are caused by germ-line mutations in genes encoding components of the RAS mitogen-activated protein kinase (MAPK) pathway. RIT1 was recently reported as a disease gene for NS, but the number of published cases is still limited. METHODS: We sequenced RIT1 in 310 mutation-negative individuals with a suspected RASopathy and prospectively in individuals who underwent genetic testing for NS. Using a standardized form, we recorded clinical features of all RIT1 mutation-positive patients. Clinical and genotype data from 36 individuals with RIT1 mutation reported previously were reviewed. RESULTS: Eleven different RIT1 missense mutations, three of which were novel, were identified in 33 subjects from 28 families; codons 57, 82, and 95 represent mutation hotspots. In relation to NS of other genetic etiologies, prenatal abnormalities, cardiovascular disease, and lymphatic abnormalities were common in individuals with RIT1 mutation, whereas short stature, intellectual problems, pectus anomalies, and ectodermal findings were less frequent. CONCLUSION: RIT1 is one of the major genes for NS. The RIT1-associated phenotype differs gradually from other NS subtypes, with a high prevalence of cardiovascular manifestations, especially hypertrophic cardiomyopathy, and lymphatic problems.Genet Med 18 12, 1226-1234.

• MeSH
• fenotyp MeSH
• genetické asociační studie MeSH
• genotyp MeSH
• hypertrofická kardiomyopatie genetika   patologie   MeSH
• lidé MeSH
• Noonanové syndrom genetika   patologie   MeSH
• Ras proteiny genetika   MeSH
• rodokmen MeSH
• vrozené srdeční vady genetika   patologie   MeSH
• zárodečné mutace MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Ras proteiny MeSH
• RIT1 protein, human MeSH Prohlížeč

We performed the genetic analysis of Rasopathy syndromes in patients from Central European by direct sequencing followed by next generation sequencing of genes associated with Rasopathies. All 51 patients harboured the typical features of Rasopathy syndromes. Thirty-five mutations were identified in the examined patients (22 in PTPN11, two in SOS1, one in RIT1, one in SHOC2, two in HRAS, three in BRAF, two in MAP2K1 and two in the NF1 gene). Two of them (p.Gly392Glu in the BRAF gene and p.Gln164Lys in the MAP2K1 gene) were novel with a potentially pathogenic effect on the structure of these proteins. Statistically significant differences in the presence of pulmonary stenosis (63.64% vs. 23.81%, P = 0.013897) and cryptorchidism (76.47% vs. 30%, P = 0.040224) were identified as the result of comparison of the prevalence of phenotypic features in patients with the phenotype of Noonan syndrome and mutation in the PTPN11 gene, with the prevalence of the same features in patients without PTPN11 mutation. Cryptorchidism as a statistically significant feature in our patients with PTPN11 mutation was not reported as significant in other European countries (Germany, Italy and Greece). The majority of mutations were clustered in exons 3 (45.45%), 8 (22.73%), and 13 (22.73%) of the PTPN11 gene.

• Klíčová slova
• BRAF, MAP2K1, PTPN11, Rasopathies, cardio-facio-cutaneous syndrome, central Europe, noonan syndrome,
• MeSH
• běloši genetika   MeSH
• dítě MeSH
• dospělí MeSH
• ektodermální dysplazie genetika   MeSH
• exony MeSH
• faciální stigmatizace MeSH
• fenotyp MeSH
• intracelulární signální peptidy a proteiny genetika   MeSH
• kojenec MeSH
• kryptorchismus genetika   MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mutační analýza DNA * MeSH
• neprospívání genetika   MeSH
• Noonanové syndrom genetika   MeSH
• předškolní dítě MeSH
• protein SOS1 genetika   MeSH
• Ras proteiny genetika   MeSH
• stenóza pulmonální chlopně genetika   MeSH
• tyrosinfosfatasa nereceptorového typu 11 genetika   MeSH
• vrozené srdeční vady genetika   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• intracelulární signální peptidy a proteiny MeSH
• protein SOS1 MeSH
• PTPN11 protein, human MeSH Prohlížeč
• Ras proteiny MeSH
• RIT1 protein, human MeSH Prohlížeč
• SHOC2 protein, human MeSH Prohlížeč
• tyrosinfosfatasa nereceptorového typu 11 MeSH