Cleft palate and hypopituitarism in a patient with Noonan‐like syndrome with loose anagen hair‐1

Noonan syndrome (NS), the most common of the RASopathies, is a developmental disorder caused by heterozygous germline mutations in genes encoding proteins in the RAS‐MAPK signaling pathway. Noonan‐like syndrome with loose anagen hair (NSLH, including NSLH1, OMIM #607721 and NSLH2, OMIM #617506) is characterized by typical features of NS with additional findings of macrocephaly, loose anagen hair, growth hormone deficiency in some, and a higher incidence of intellectual disability. All NSLH1 reported cases to date have had an SHOC2 c.4A>G, p.Ser2Gly mutation; NSLH2 cases have been reported with a PPP1CB c.146G>C, p.Pro49Arg mutation, or c.166G>C, p.Ala56Pro mutation. True cleft palate does not appear to have been previously reported in individuals with NS or with NSLH. While some patients with NS have had growth hormone deficiency (GHD), other endocrine abnormalities are only rarely documented. We present a female patient with NSLH1 who was born with a posterior cleft palate, micrognathia, and mild hypotonia. Other findings in her childhood and young adulthood years include hearing loss, strabismus, and hypopituitarism with growth hormone, thyroid stimulating hormone (TSH), and gonadotropin deficiencies. The SHOC2 mutation may be responsible for this patient's additional features of cleft palate and hypopituitarism.     

The novel RAF1 mutation p.(Gly361Ala) located outside the kinase domain of the CR3 region in two patients with Noonan syndrome,including one with a rare brain tumor

Noonan syndrome is characterized by typical craniofacial dysmorphism, postnatal growth retardation, congenital heart defect, and learning difficulties and belongs to the RASopathies, a group of neurodevelopmental disorders caused by germline mutations in genes encoding components of the RAS‐MAPK pathway. Mutations in the RAF1 gene are associated with Noonan syndrome, with a high prevalence of hypertrophic cardiomyopathy (HCM). RAF1 mutations cluster in exons encoding the conserved region 2 (CR2), the kinase activation segment of the CR3 domain, and the C‐terminus. We present two boys with Noonan syndrome and the identical de novo RAF1 missense variant c.1082G>C/p.(Gly361Ala) affecting the CR3, but located outside the kinase activation segment. The p.(Gly361Ala) mutation has been identified as a RAF1 allele conferring resistance to RAF inhibitors. This amino acid change favors a RAF1 conformation that allows for enhanced RAF dimerization and increased intrinsic kinase activity. Both patients with Noonan syndrome showed typical craniofacial dysmorphism, macrocephaly, and short stature. One individual developed HCM and was diagnosed with a disseminated oligodendroglial‐like leptomeningeal tumor (DOLT) of childhood at the age of 9 years. While there is a well‐established association of NS with malignant tumors, especially childhood hemato‐oncological diseases, brain tumors have rarely been reported in Noonan syndrome. Our data demonstrate that mutation scanning of the entire coding region of genes associated with Noonan syndrome is mandatory not to miss rare variants located outside the known mutational hotspots.

     

RASopathy‐Associated CBL Germline Mutations Cause Aberrant Ubiquitylation and Trafficking of EGFR

Noonan syndrome, a congenital disorder comprising a characteristic face, short stature, heart defects, learning difficulties, and a predisposition to malignancies, is caused by heterozygous germline mutations in genes encoding components of RAS‐MAPK signaling pathways. Mutations in the CBL tumor suppressor gene have been reported in patients with a Noonan syndrome‐like phenotype. CBL encodes a multivalent adaptor protein with ubiquitin ligase activity, which promotes ubiquitylation and vesicle‐mediated internalization and degradation of the epidermal growth factor (EGF) receptor (EGFR). We investigated the functional consequences of disease‐associated CBL amino acid changes p.K382E, p.D390Y, and p.R420Q on ligand‐induced EGFR trafficking. Expression of CBL^K382E, CBL^D390Y, or CBL^R420Q in COS‐7 cells resulted in increased levels of surface EGFR and reduced amounts of intracellular EGFR; both consequences indicate ineffective EGFR internalization. Accordingly, receptor‐mediated uptake of EGF was decreased. Furthermore, the p.K382E, p.D390Y, and p.R420Q lesions impaired CBL‐mediated EGFR ubiquitylation and degradation. Together, these data indicate that pathogenic CBL mutations severely affect vesicle‐based EGFR trafficking. Since we detected enhanced ERK phosphorylation in cells expressing mutant CBL, we conclude that aberrant EGFR trafficking contributes to augmented RAS‐MAPK signaling, the common trait of Noonan syndrome and related RASopathies. Thus, our data suggest that EGFR trafficking is a novel disease‐relevant regulatory level in the RASopathy network.     

Noonan-like syndrome with loose anagen hair associated with growth hormone insensitivity and atypical neurological manifestations

Noonan-like syndrome with loose anagen hair (NS/LAH; OMIM 607721), recently related to the invariant c.4A>G missense change in SHOC2, is characterized by features reminiscent of Noonan syndrome. Ectodermal involvement, short stature associated with growth hormone (GH) deficiency (GHD), and cognitive deficits are common features. We report on a patient with molecularly confirmed NS/LAH exhibiting severe short stature associated with GH insensitivity (GHI), and chronic complex tics, a neurological feature never described before in this syndrome. IGF1 generation test revealed only a blunted increase in IGF1 after exogenous GH treatment, revealing mild GH insensitivity associated with proper STAT5 activation. Most common causes of secondary tics in childhood were excluded.     

First‐year growth in children with Noonan syndrome: Associated with feeding problems?

Children with Noonan syndrome show rapid decline of growth in the first year of life and feeding problems are present in over 50%. The aim of this study was to explore whether growth decelerates because of feeding problems or other Noonan syndrome‐related factors. We performed a retrospective, longitudinal cohort study of clinically and genetically diagnosed subjects with Noonan syndrome (n = 143). Questionnaires about the phenotypic–genotypic profile and reported feeding problems were sent to eligible subjects. Data on first‐year growth was obtained from growth charts. Ninety‐one participants were excluded because of different criteria. A total of 52 subjects with Noonan syndrome were included. The largest decline in weight and length standard deviation score (SDS) occurred in the first 2.5 months after birth (−1.93 and −1.15, respectively), with feeding problems causing a decline of 0.57 SDS in the remaining months. At 1 year, children with feeding problems were on average 290 g lighter and 0.8 cm shorter than children without feeding problems. Weight gain was also negatively influenced by having a PTPN11 mutation (n = 39) and a higher gestational age, whereas children of parents with Noonan syndrome and with a higher birth weight gained more weight. Growth in length was reduced by having cardiac surgery and a higher gestational age, but positively influenced by birth length and maternal height. Growth in children with Noonan syndrome is impaired right after birth and only partially associated with feeding problems. In addition, several specific Noonan syndrome‐related factors seem to influence growth in the first year.     

Clinical analysis of Noonan syndrome caused by RRAS2 mutations and literature review

Noonan syndrome is a common developmental disorder characterized by distinctive facial dysmorphism, short stature, congenital heart defects, pectus deformity, and developmental delay. It is related to the abnormal activation of genes involved in the RAS-MAPK signaling pathway, more than a dozen of which can be affected. However, mutations of the RRAS2 gene are rare, with only 6 different RRAS2 variants in 13 patients reported to date. In this case report, whole-exome sequencing revealed a novel heterozygous variant in the RRAS2 gene NM_012250: c.212G > A, p.(Gly71Glu). Phenotypically, our patient had typical Noonan syndrome-related clinical manifestations consistent with published reports, such as short stature, facial dysmorphism, short neck, patent foramen ovale, moderate global developmental delay, and hearing impairment. In addition, our patient also had a distal middle finger deformity and hair defect, which have not been reported in previous cases. We analyzed the clinical characteristics of all patients with Noonan syndrome caused by RRAS2 variants and reviewed the literature. This discovery expands the genetic and phenotypic spectrum of Noonan syndrome.     

A Novel SHOC2 Variant in Rasopathy

Rasopathies are a group of genetic disorders caused by germline mutations in multiple genes of the Extracellular signal‐Regulated Kinases 1 and 2 (ERK1/2) pathway. The only previously identified missense mutation in SHOC2, a scaffold protein of the ERK1/2 pathway, led to Noonan‐like syndrome with loose anagen hair. Here, we report a novel mutation in SHOC2(c.519G>A; p.M173I) that leads to a Rasopathy with clinical features partially overlapping those occurring in Noonan and cardiofaciocutaneous syndromes. Studies to clarify the significance of this SHOC2 variant revealed that the mutant protein has impaired capacity to interact with protein phosphatase 1c (PP1c), leading to insufficient activation of RAF‐1 kinase. This SHOC2 variant thus is unable to fully rescue ERK1/2 activity in cells depleted of endogenous SHOC2. We conclude that SHOC2 mutations can cause a spectrum of Rasopathy phenotypes in heterozygous individuals. Importantly, our work suggests that individuals with mild Rasopathy symptoms may be underdiagnosed.     

The RRAS2 pathogenic variant p.Q72L produces severe Noonan syndrome with hydrocephalus: A case report

Noonan syndrome (NS) is the most common disease among RASopathies, characterized by short stature, distinctive facial features, congenital cardiac defects, and variable developmental delay. NS rarely presents with overt neurologic manifestations, in particular hydrocephalus. Recent evidence suggests that pathogenic variants in the gene RRAS2 are a rare cause of NS. Specifically, an RRAS2 pathogenic variant, p.Q72L, may be particularly severe, manifesting with lethal neurologic findings. Here, we report a NS patient with documented p.Q72L variant in RRAS2. The patient was identified in utero to have hydrocephalus and a Dandy Walker malformation. Postnatal examination revealed multiple dysmorphic features, some reminiscent of NS including low-set posteriorly rotated ears, redundant nuchal skin, widely spaced nipples, and cryptorchidism. Despite suspicion of NS, results of a 14-gene Noonan syndrome panel (Invitae) were negative. Follow-up rapid whole exome sequencing revealed a de novo p.Q72L variant in RRAS2, a poorly studied gene recently identified as a cause of NS. The patient herein reported brings to three the total number of cases reported with the RRAS2 p.Q72L pathogenic variant. All three documented patients presented with a particularly fulminant course of NS, which included hydrocephalus. RRAS2, specifically p.Q72L, should be considered in severe NS cases with neurologic manifestations.     

RAF1 variant in a patient with Noonan syndrome with multiple lentigines and craniosynostosis

We report the case of a 14 years and 8 months girl, who is the first child of nonconsanguineous parents, with short stature, obstructive hypertrophic cardiomyopathy, multiple facial lentigines, high and wide forehead, downslanting palpebral fissures, low‐set ears, short neck, and pectus excavatum; all features suggestive of Noonan syndrome with multiple lentigines (NSML). In addition, the patient exhibited craniosynostosis. Molecular analysis of rats sarcoma (RAS)/mitogen‐activated protein kinase (MAPK) pathway genes with high‐resolution melting curve analysis followed by sequencing showed a RAF1 amino acid substitution of valine to glycine at position 263 (p.V263G). The present report provides clinical data regarding the first association of a RAF1 variant and craniosynostosis in a patient with clinical diagnosis of NSML.     

ADA2 deficiency in a patient with Noonan syndrome‐like disorder with loose anagen hair: The co‐occurrence of two rare syndromes

Noonan syndrome‐like disorder with loose anagen hair (NS/LAH) is one of the RASopathies, a group of clinically related developmental disorders caused by germline mutations in genes that encode components acting in the RAS/MAPK pathway. Among RASopathies, NS/LAH (OMIM 607721) is an extremely rare, multiple anomaly syndrome characterized by dysmorphic facial features similar to those observed in Noonan syndrome along with some distinctive ectodermal findings including easily pluckable, sparse, thin, and slow‐growing hair. ADA2 deficiency (DADA2, OMIM 615688) is a monogenic autoinflammatory disorder caused by homozygous or compound heterozygous mutations in ADA2, with clinical features including recurrent fever, livedo racemosa, hepatosplenomegaly, and strokes as well as immune dysregulation. This is the first report of NS/LAH and ADA2 deficiency in the same individual. We report on a patient presenting with facial features, recurrent infections and ectodermal findings in whom both the clinical and molecular diagnoses of NS/LAH and ADA2 deficiency were established, respectively.     

Patient with anomalous skin pigmentation expands the phenotype of ARID2 loss‐of‐function disorder,a SWI/SNF‐related intellectual disability

ARID2 loss‐of‐function is associated with a rare genetic disorder characterized in 14 reported patients to date. ARID2 encodes a member of the SWItch/sucrose non‐fermentable chromatin remodeling complex. Other genes encoding subunits of this complex, such as ARID1A, ARID1B, and SMARCA2, are mutated in association with Coffin‐Siris syndrome (CSS) and Nicolaides Baraitser syndrome (NCBRS) phenotypes. Previously reported ARID2 mutations manifested clinically with a CSS‐like phenotype including intellectual disability, coarsened facial features, fifth toenail hypoplasia, and other recognizable dysmorphisms. However, heterogeneity exists between previously reported patients with some patients showing more overlapping features with NCBRS. Herein, we present a patient with a novel disease‐causing ARID2 loss‐of‐function mutation. His clinical features included intellectual disability, coarse and dysmorphic facial features, toenail hypoplasia, ADHD, short stature, and delayed development consistent with prior reports. Our patient also presented with previously unreported clinical findings including ophthalmologic involvement, persistent fetal fingertip and toetip pads, and diffuse hyperpigmentary and hypopigmentary changes sparing his face, palms, and soles. The anomalous skin findings are particularly of interest given prior literature outlining the role of ARID2 in melanocyte homeostasis and melanoma. This clinical report and review of the literature is further affirming of the characteristic symptoms and expands the phenotype of this newly described and rare syndrome.     

Expanding the phenotypic spectrum of cardiospondylocarpofacial syndrome: From a detailed clinical and radiological observation of a boy with a novel missense variant in MAP3K7

Cardiospondylocarpofacial syndrome (CSCF; OMIM#157800) is characterized by growth impairment, failure to thrive in infancy, multiple valvular disease, carpal and tarsal fusions, vertebral fusions, and joint hypermobility. It is caused by pathogenic variants of MAP3K7, which encodes transforming growth factor-β activated kinase 1 (TAK1), a member of the mitogen-activated protein kinase kinase kinase family (MAPKKK). Only eight individuals with molecularly confirmed CSCF have been reported. Here, we report the first Asian CSCF male with a novel missense variant of MAP3K7 (NM_145331.3: c.467A > T: p.Asp156Val). We compared and reviewed the clinical and molecular findings in previously reported CSCF cases and the present case to better delineate the phenotype of CSCF. In addition to the main symptoms of CSCF, the present case had a mixed phenotype of Ehlers–Danlos syndrome (EDS) and Noonan syndrome. Taking this case together with the previously reported cases, CSCF may overlap with the phenotypes of EDS and Noonan syndrome, suggesting that this finding may contribute to diagnosing CSCF. Another major achievement of this research is to successfully capture the process of carpal fusion in a CSCF case radiographically. This work may expand the phenotypic spectrum of CSCF.     

6例Noonan综合征患者临床特点及重组人生长激素治疗效果分析

目的 本研究将总结6例Noonan综合征(NS)患者的临床特点、基因诊断结果及对重组人生长激素(rh GH)治疗的反应。方法 回顾性总结2009年5月至2015年8月在北京协和医院内分泌科矮小门诊的6例NS患者的临床特点。5例以0.1 IU/(kg·d)为起始剂量应用rh GH,进行定期随访,并与年龄/性别相匹配的同期应用rh GH的10例特纳综合征(TS)和10例生长激素缺乏症(GHD)患者进行比较。结果 6例患者均存在NS的典型临床表现;5例经rh GH治疗后,年生长速度显著增加(P0.01);NS与TS患者rh GH疗效相似,随访各点均无显著性差异;但GHD患者相比,在应用rh GH后疗效欠佳;不良事件:2例NS在随访期出现亚临床甲状腺功能减低。结论 NS患者具有典型的临床表现,基因检查有助于明确诊断,rh GH治疗有显著疗效及较高的安全性。     

Novel PPP1CB‐ALK fusion in spindle cell tumor defined by S100 and CD34 coexpression and distinctive stromal and perivascular hyalinization

A novel group of S100‐ and CD34‐positive spindle cell tumors with distinctive stromal and perivascular hyalinization harboring recurrent gene fusions involving kinases including RAF1, BRAF, NTRK1/2/3, and RET have been recently reported. To our knowledge, no such cases harboring ALK rearrangements have been identified. We report a previously healthy 41‐year‐old male with a 12‐cm intramuscular shoulder mass. The tumor was composed of bland‐appearing spindled to epithelioid cells, arranged in a patternless pattern in a background of loose myxoid stroma containing striking amianthoid‐like stromal collagen and perivascular rings. In accordance with the previously reported tumors, the tumor cells showed diffuse immunopositivity with S100 and CD34, while lacking SOX10 expression. Targeted RNA‐based next‐generation sequencing identified a novel serine/threonine‐protein phosphatase PP1‐beta‐catalytic subunit (PPP1CB)‐ALK fusion gene. Although ALK break‐apart was not detected by FISH, likely due to a paracentric inversion of chromosome 2, the presence of the fusion was confirmed by Sanger sequencing showing a 10‐bp linker between exon 6 of PPP1CB and intron 19 of ALK while maintaining reading frame. Subsequent ALK‐1 immunostain exhibited diffuse cytoplasmic staining in the tumor cells. Our case expands the molecular genetic spectrum of the distinctive group of spindle cell tumors with CD34/S100+ immunophenotype, supporting the important role of various kinases as drivers of oncogenesis. Awareness of this entity including its unique morphologic and immunophenotypic features as well as its interchangeable kinase gene fusions is crucial for correct classification and potential targeted therapy, particularly in aggressive subsets.     

Noonan syndrome and neurofibromatosis type I in a family with a novel mutation in NF1

Noonan syndrome (NS) and neurofibromatosis type I (NF1) belong to a group of clinically related disorders that share a common pathogenesis, dysregulation of the RAS‐MAPK pathway. NS is characterized by short stature, heart defect, pectus deformity and facial dysmorphism, whereas skin manifestations, skeletal defects, Lisch nodules and neurofibromas are characteristic of NF1. Both disorders display considerable clinical variability. Features of NS have been observed in individuals with NF1 –a condition known as neurofibromatosis–Noonan syndrome (NFNS). The major gene causing NFNS is NF1. Rarely, a mutation in PTPN11 in addition to an NF1 mutation is present. We present the clinical and molecular characterization of a family displaying features of both NS and NF1, with complete absence of neurofibromas. To investigate the etiology of the phenotype, mutational analysis of NF1 was conducted, revealing a novel missense mutation in exon 24, p.L1390F, affecting the GAP‐domain. Additional RAS‐MAPK pathway genes were examined, but no additional mutations were identified. We confirm that NF1 mutations are involved in the etiology of NFNS. Furthermore, based on our results and previous studies we suggest that evaluation of the GAP‐domain of NF1 should be prioritized in NFNS.     

Clinical and functional characterization of a novel RASopathy‐causing SHOC2 mutation associated with prenatal‐onset hypertrophic cardiomyopathy

SHOC2 is a scaffold protein mediating RAS‐promoted activation of mitogen‐activated protein kinase (MAPK) signaling in response to extracellular stimuli. A recurrent activating mutation in SHOC2 (p.Ser2Gly) causes Mazzanti syndrome, a RASopathy characterized by features resembling Noonan syndrome and distinctive ectodermal abnormalities. A second mutation (p.Met173Ile) supposed to cause loss‐of‐function was more recently identified in two individuals with milder phenotypes. Here, we report on the third RASopathy‐causing SHOC2 mutation (c.807_808delinsTT, p.Gln269_His270delinsHisTyr), which was found associated with prenatal‐onset hypertrophic cardiomyopathy. Structural analyses indicated a possible impact of the mutation on the relative orientation of the two SHOC2's leucine‐rich repeat domains. Functional studies provided evidence of its activating role, revealing enhanced binding of the mutant protein to MRAS and PPP1CB, and increased signaling through the MAPK cascade. Differing from SHOC2 ^S2G, SHOC2 ^{Q269_H270delinsHY} is not constitutively targeted to the plasma membrane. These data document that diverse mechanisms in SHOC2 functional dysregulation converge toward MAPK signaling upregulation.     

A child with Myhre syndrome presenting with corectopia and tetralogy of Fallot

Myhre syndrome is a rare autosomal dominant disorder caused by a narrow spectrum of missense mutations in the SMAD4 gene. Typical features of this disorder are distinctive facial appearance, deafness, intellectual disability, cardiovascular abnormalities, short stature, short hands and feet, compact build, joint stiffness, and skeletal anomalies. The clinical features generally appear during childhood and become more evident in older patients. Therefore, the diagnosis of this syndrome in the first years of life is challenging. We report a 2‐year‐old girl diagnosed with Myhre syndrome by whole exome sequencing (WES) that revealed the recurrent p.Ile500Val mutation in the SMAD4 gene. Our patient presented with growth deficiency, dysmorphic features, tetralogy of Fallot, and corectopia (also known as ectopia pupillae). The girl we described is the youngest patient with Myhre syndrome. Moreover, corectopia and tetralogy of Fallot have not been previously reported in this disorder.     

Mutation analysis of the SHOC2 gene in Noonan-like syndrome and in hematologic malignancies

Noonan syndrome is an autosomal dominant disease characterized by dysmorphic features, webbed neck, cardiac anomalies, short stature and cryptorchidism. It shows phenotypic overlap with Costello syndrome and cardio-facio-cutaneous (CFC) syndrome. Noonan syndrome and related disorders are caused by germline mutations in genes encoding molecules in the RAS/MAPK pathway. Recently, a gain-of-function mutation in SHOC2, p.S2G, has been identified as causative for a type of Noonan-like syndrome characterized by the presence of loose anagen hair. In order to understand the contribution of SHOC2 mutations to the clinical manifestations of Noonan syndrome and related disorders, we analyzed SHOC2 in 92 patients with Noonan syndrome and related disorders who did not exhibit PTPN11, KRAS, HRAS, BRAF, MAP2K1/2, SOS1 or RAF1 mutations. We found the previously identified p.S2G mutation in eight of our patients. We developed a rapid detection system to identify the p.S2G mutation using melting curve analysis, which will be a useful tool to screen for the apparently common mutation. All the patients with the p.S2G mutation showed short stature, sparse hair and atopic skin. Six of the mutation-positive patients showed severe mental retardation and easily pluckable hair, and one showed leukocytosis. No SHOC2 mutations were identified in leukemia cells from 82 leukemia patients. These results suggest that clinical manifestations in SHOC2 mutation-positive patients partially overlap with those in patients with typical Noonan or CFC syndrome and show that easily pluckable/loose anagen hair is distinctive in SHOC2 mutation-positive patients.     

Growth curves for height in Noonan syndrome

Growth retardation is a relatively consistent feature of Noonan syndrome but a standardized growth curve for height has never been calculated. Analysis of retrospective growth data on 112 patients with Noonan syndrome has permitted the establishment of preliminary reference growth standards for height for males and females. The results confirm the clinical impression that short stature among this group of patients occurs uniformly and is independent of chronological age. Various factors which may modify this are considered.