Familial cardiofaciocutaneous syndrome in a father and a son with a novel MEK2 mutation

Obstetrical and neonatal outcomes of cardio-facio-cutaneous syndrome: Prenatal consequences of Ras/MAPK dysregulation

We systematically delineated the prenatal phenotype, and obstetrical and neonatal outcomes of the RASopathy cardio-facio-cutaneous (CFC) syndrome. A comprehensive, retrospective medical history survey was distributed to parents of children with confirmed CFC in collaboration with CFC International, Inc. Data were collected on CFC gene variant, maternal characteristics, pregnancy course, delivery, and neonatal outcomes with the support of medical records. We identified 43 individuals with pathogenic variants in BRAF (81%), MEK1 (14%), or MEK2 (5%) genes. The median age was 8.5 years. Hyperemesis gravidarum, gestational diabetes, gestational hypertension, and preeclampsia occurred in 5/43 (12%), 4/43 (9%), 3/43 (7%), and 3/43 (7%) of pregnancies, respectively. Second and third trimester ultrasound abnormalities included polyhydramnios, macrocephaly, macrosomia, and renal and cardiac abnormalities. Delivery occurred via spontaneous vaginal, operative vaginal, or cesarean delivery in 15/42 (36%), 7/42 (16%), and 20/42 (48%), respectively. Median gestational age at delivery was 37 weeks and median birth weight was 3501 grams. Germline pathogenic vaiants had mutiple congenital consequences including polyhydramnios, renal and cardiac abnormalities, macrosomia, and macrocephaly on second and third trimester ultrasound. Elevated rates of operative delivery and neonatal complications were also noted. Understanding and defining a prenatal phenotype may improve prenatal prognostic counseling and outcomes.

Familial cardio-facio-cutaneous syndrome: Vertical transmission of the BRAF p.G464R pathogenic variant and review of the literature

Cardio-facio-cutaneous syndrome (CFC) is one of the RASopathies and is caused by germline mutations that activate the Ras/mitogen-activated protein kinase (MAPK) pathway. CFC is due to heterozygous germline mutations in protein kinases BRAF, MEK1, or MEK2 and rarely in KRAS, a small GTPase. CFC is a multiple congenital anomaly disorder in which individuals may have craniofacial dysmorphia, heart issues, skin and hair anomalies, and delayed development. Pathogenic variants for CFC syndrome are usually considered de novo because vertical transmission has only been reported with MEK2 and KRAS. The index case was a 3-year-old male with features consistent with the clinical diagnosis of CFC. Sequencing revealed a previously reported heterozygous likely pathogenic variant BRAF p.G464R. Upon detailed family history, the index case's pregnant mother was noted to have similar features to her son. Targeted familial testing of the BRAF pathogenic variant was performed on the mother, confirming her diagnosis. Prenatal genetic testing for the fetus was declined, but postnatal molecular testing of the index case's sister was positive for the familial BRAF p.G464R variant. Functional analysis of the variant demonstrated increased kinase activity. We report the first identified vertically transmitted functional BRAF pathogenic variant. Our findings emphasize the importance of obtaining a comprehensive evaluation of family members and that activating pathogenic variants within the canonical MAPK cascade mediated by BRAF are compatible with human reproduction.

Cardiofaciocutaneous syndrome with rare structural variant in DOCK8 gene associated with neurodevelopmental disorders

We describe a girl with clinical signs of cardiofaciocutaneous syndrome who simultaneously presents a mutation in the BRAF gene and a 9p24.3 microduplication. This genetic condition has never been described in the literature and could explain the phenotypic variability observed in the girl.

Effect of disease-associated SLC9A9 mutations on protein-protein interaction networks: implications for molecular mechanisms for ADHD and autism

Na⁺/H⁺ Exchanger 9 (NHE9) is an endosomal membrane protein encoded by the Solute Carrier 9A, member 9 gene (SLC9A9). SLC9A9 has been implicated in attention deficit hyperactivity disorder (ADHD), autism spectrum disorders (ASDs), epilepsy, multiple sclerosis and cancers. To better understand the function of NHE9 and the effects of disease-associated variants on protein-protein interactions, we conducted a quantitative analysis of the NHE9 interactome using co-immunoprecipitation and isobaric labeling-based quantitative mass spectrometry. We identified 100 proteins that interact with NHE9. These proteins were enriched in known functional pathways for NHE9: the endocytosis, protein ubiquitination and phagosome pathways, as well as some novel pathways including oxidative stress, mitochondrial dysfunction, mTOR signaling, cell death and RNA processing pathways. An ADHD-associated mutation (A409P) significantly altered NHE9's interactions with a subset of proteins involved in caveolae-mediated endocytosis and MAP2K2-mediated downstream signaling. An ASD nonsense mutation in SLC9A9, R423X, produced no-detectable amount of NHE9, suggesting the overall loss of NHE9 functional networks. In addition, seven of the NHE9 interactors are products of known autism candidate genes (Simons Foundation Autism Research Initiative, SFARI Gene) and 90% of the NHE9 interactome overlap with SFARI protein interaction network PIN (p < 0.0001), supporting the role of NHE9 interactome in ASDs molecular mechanisms. Our results provide a detailed understanding of the functions of protein NHE9 and its disrupted interactions, possibly underlying ADHD and ASDs. Furthermore, our methodological framework proved useful for functional characterization of disease-associated genetic variants and suggestion of druggable targets.

Variability in clinical and neuropsychological features of individuals with MAP2K1 mutations

Mutations in MAP2K1, a gene expressed within the RAS-mitogen activated protein kinase (RAS/MAPK) pathway, are generally associated with the clinical phenotype of cardiofaciocutaneous syndrome. Here we describe two male patients (ages 16 and 20 years) with mutations in MAP2K1 and heterogeneous clinical presentations. Both young men had short stature, some facial features suggesting a RASopathy and minimal cardiac involvement. Detailed medical and neuropsychological findings are presented alongside a comprehensive review of features of patients with MAP2K1 mutations reported in the literature. Published studies have indicated that cognitive functioning of individuals with MAP2K1 mutations can range from severe intellectual disability to mildly below average. Neither of the individuals presented here had severe intellectual disability, and one had intellectual functioning within the average range. Neurodevelopmental concerns that were common among our two patients included fine motor difficulties, slow processing speed, reduced attention span, learning disabilities, and diminished energy/alertness. Taken together, our findings demonstrate that mutations in MAP2K1, which are frequently associated with neurological complications and intellectual disability, can be associated with a milder clinical and neurocognitive profile more typical of individuals with Noonan syndrome. Variability of expression may arise from a complex interplay between RAS/MAPK pathway genotype, epigenetics, medical and obstetric factors, and environmental influences. © 2016 Wiley Periodicals, Inc.