Noonan syndrome (NS) is an autosomal dominant disorder consisting of short stature, short and/or webbed neck, distinctive facial features, cardiac abnormalities, cryptorchidism, and coagulation defects. NS exhibits genetic heterogeneity, associated with mutated genes that participate in RAS-mitogen-activated protein kinase signal transduction. Recently, a new gene (RIT1) was discovered as the causative gene in 17 of 180 Japanese individuals who were negative for the previously known genes for NS and were studied using exome sequencing (four patients), followed by Sanger sequencing (13 patients). The present study used the same technique in 70 Brazilian patients with NS and identified six with RIT1 missense mutations. Thus, we confirm that RIT1 is responsible for approximately 10% of the patients negative for mutations in the previously known genes. The phenotype includes a high frequency of high birth weight, relative macrocephaly, left ventricular hypertrophy, and ectodermal findings, such as curly hair, hyperpigmentation, and wrinkled palms and soles. Short stature and pectus deformity were less frequent. The majority of patients with a RIT1 mutation did not show apparent intellectual disability. Because of the relatively high frequency of mutations in RIT1 among patients with NS and its occurrence in different populations, we suggest that it should be added to the list of genes included in panels for the molecular diagnosis of NS through targeted next-generation sequencing.
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http://dx.doi.org/10.1002/ajmg.a.36722 | DOI Listing |
Eur J Pediatr
December 2024
Dept. of Research and Development, SeysCentra, Malden, The Netherlands.
Unlabelled: Children with Noonan syndrome-like RASopathies are at increased risk for developing feeding problems due to comorbid organic impairments at an early age, such as gastrointestinal problems or other organicity. Their feeding problems can ultimately often be classified as avoidant/restrictive food intake disorder, for which behavioral therapy is the first-choice treatment. The research question in this study is whether this treatment leads to similar results as in children without these RASopathies.
View Article and Find Full Text PDFHum Brain Mapp
December 2024
Division of Interdisciplinary Brain Sciences, Department of Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, California, USA.
Neurodevelopmental disorders (NDDs) can severely impact functioning yet effective treatments are limited. Greater insight into the neurobiology underlying NDDs is critical to the development of successful treatments. Using a genetics-first approach, we investigated the potential of advanced diffusion-weighted imaging (DWI) techniques to characterize the neural microstructure unique to neurofibromatosis type 1 (NF1) and Noonan syndrome (NS).
View Article and Find Full Text PDFInt J Dev Neurosci
December 2024
Department of Pediatric Neurology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China.
Background: According to previous literature reports, PTPN11 gene variants account for approximately 50% of Noonan syndrome (NS) cases and 85% of Leopard syndrome (LS) cases. Several patients who were diagnosed with NS or LS complicated with Chiari I malformation (CIM) and/or syringomyelia have been reported to have a PTPN11 variant. However, it is not always clear whether the association between CIM and/or syringomyelia and PTPN11 variants is real or random.
View Article and Find Full Text PDFZhonghua Yi Xue Yi Chuan Xue Za Zhi
December 2024
Center for Obstetrics and Gynecology, the Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing, Jiangsu 210008, China.
Objective: To report on the phenotype of an adult patient with 2p23.2p22.1 duplication and explore its genotype-phenotype correlation.
View Article and Find Full Text PDFBackground And Aims: Neurofibromatosis-Noonan syndrome (NFNS) is an extremely rare genetic entity combining the clinical phenotype of two conditions: neurofibromatosis type 1 syndrome (NF1) and Noonan syndrome (NS). Nevertheless, many inconsistencies reside in our understanding of this condition, mainly its clinical features and genetic background. Through this systematic review, we aim to shed light on the epidemiological features, the broad clinical spectrum, the underlying genetic defects and the associated comorbidities of NFNS.
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