Noonan syndrome associated with both a new Jnk-activating familial SOS1 and a de novo RAF1 mutations.
Summary of "Noonan syndrome associated with both a new Jnk-activating familial SOS1 and a de novo RAF1 mutations."
Noonan syndrome is a genetic condition characterized by congenital heart defects, short stature, and characteristic facial features. Familial or de novo mutations in PTPN11, RAF1, SOS1, KRAS, and NRAS are responsible for 60-75% of the cases, thus, additional genes are expected to be involved in the pathogenesis. In addition, the genotype-phenotype correlation has been hindered by the highly variable expressivity of the disease. For all these reasons, expanding the genotyped and clinically evaluated case numbers will benefit the clinical community. A mutation analysis has been performed on RAF1, SOS1, and GRB2, in 24 patients previously found to be negative for PTPN11 and KRAS mutations. We identified four mutations in SOS1 and one in RAF1, while no GRB2 variants have been found. Interestingly, the RAF1 mutation was present in a patient also carrying a newly identified p.R497Q familial SOS1 mutation, segregating with a typical Noonan Syndrome SOS1 cutaneous phenotype. Functional analysis demonstrated that the R497Q SOS1 mutation leads to Jnk activation, but has no effect on the Ras effector Erk1. We propose that this variant might contribute to the onset of the peculiar ectodermal traits displayed by the propositus amidst the more classical Noonan syndrome presentation. To our knowledge, this is the first reported case of a patient harboring mutations in two genes, with an involvement of both Ras and Rac1 pathways, indicating that SOS1 may have a role of modifier gene that might contribute the variable expressivity of the disease, evidencing a genotype-phenotype correlation in the family. (c) 2010 Wiley-Liss, Inc.
Dipartimento di Biologia e Genetica per le Scienze Mediche, Università degli Studi di Milano, Milano, Italy.
This article was published in the following journal.
Name: American journal of medical genetics. Part A
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20683980
- DOI: http://dx.doi.org/10.1002/ajmg.a.33564
Medical and Biotech [MESH] Definitions
A multifaceted disorder characterized by short stature, webbed neck, ptosis, skeletal malformations, hypertelorism, hormonal imbalance, CRYPTORCHIDISM, multiple cardiac abnormalities (most commonly including PULMONARY VALVE STENOSIS), and some degree of MENTAL RETARDATION. The phenotype bears similarities to that of TURNER SYNDROME that occurs only in females and has its basis in a 45, X karyotype abnormality. However, Noonan syndrome occurs in both males and females with a normal sex chromosome constitution (46,XX and 46,XY). NS1 is due to mutations at chromosome location 12q24.1, in PTPN11, a gene encoding PROTEIN TYROSINE PHOSPHATASE, NON-RECEPTOR TYPE 11. LEOPARD SYNDROME, a disorder that has clinical features overlapping those of Noonan Syndrome, is also due to mutations in PTPN11. In addition, there is a syndrome called neurofibromatosis-Noonan syndrome. Both the PTPN11 and NF1 gene products are involved in the SIGNAL TRANSDUCTION pathway of Ras (RAS PROTEINS).
Rare congenital disorder with multiple anomalies including: characteristic dysmorphic craniofacial features, musculoskeletal abnormalities, neurocognitive delay, and high prevalence of cancer. Germline mutations in H-Ras protein can cause Costello syndrome. Costello syndrome shows early phenotypic overlap with other disorders that involve MAP KINASE SIGNALING SYSTEM (e.g., NOONAN SYNDROME and cardiofaciocutaneous syndrome).
An autosomal dominant inherited disorder (with a high frequency of spontaneous mutations) that features developmental changes in the nervous system, muscles, bones, and skin, most notably in tissue derived from the embryonic NEURAL CREST. Multiple hyperpigmented skin lesions and subcutaneous tumors are the hallmark of this disease. Peripheral and central nervous system neoplasms occur frequently, especially OPTIC NERVE GLIOMA and NEUROFIBROSARCOMA. NF1 is caused by mutations which inactivate the NF1 gene (GENES, NEUROFIBROMATOSIS 1) on chromosome 17q. The incidence of learning disabilities is also elevated in this condition. (From Adams et al., Principles of Neurology, 6th ed, pp1014-18) There is overlap of clinical features with NOONAN SYNDROME in a syndrome called neurofibromatosis-Noonan syndrome. Both the PTPN11 and NF1 gene products are involved in the SIGNAL TRANSDUCTION pathway of Ras (RAS PROTEINS).
An autosomal dominant disorder with an acronym of its seven features (LENTIGO; ELECTROCARDIOGRAM abnormalities; ocular HYPERTELORISM; PULMONARY STENOSIS; abnormal genitalia; retardation of growth; and DEAFNESS or SENSORINEURAL HEARING LOSS). This syndrome is caused by mutations of PTPN11 gene encoding the non-receptor PROTEIN TYROSINE PHOSPHATASE, type 11, and is an allelic to NOONAN SYNDROME. Features of LEOPARD syndrome overlap with those of NEUROFIBROMATOSIS 1 which is caused by mutations in the NEUROFIBROMATOSIS 1 GENES.
A syndrome of defective gonadal development in phenotypic women with a karyotype of sex chromosome monosomy (45,X or 45,XO), associated with the loss of a sex chromosome X or Y. Patients generally are of short stature with undifferentiated (streak) gonads, sexual infantilism (HYPOGONADISM), webbing of the neck, cubitus valgus, elevated GONADOTROPINS and decreased ESTRADIOL level in blood. Studies of Turner Syndrome and its variants have contributed significantly to the understanding of SEX DIFFERENTIATION. NOONAN SYNDROME bears similarity to this disorder; however, it also occurs in males, has normal karyotype, and is inherited as an autosomal dominant.
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