Is the locus for Costello syndrome on 11p?

Costello Syndrome and Umbilical Ligament Rhabdomyosarcoma in Two Pediatric Patients: Case Reports and Review of the Literature

Costello syndrome is caused by heterozygous de novo missense mutations in the protooncogene HRAS with tumor predisposition, especially rhabdomyosarcoma. We here report two pediatric patients with Costello syndrome and umbilical ligament rhabdomyosarcoma. A review of the literature published in English in MEDLINE from January 1971 to June 2016 using the search terms “Costello syndrome” and “rhabdomyosarcoma” was performed, including two new cases that we describe. Twenty-six patients with Costello syndrome and rhabdomyosarcoma were recorded with mean age of diagnosis of 2 years and 8 months. The most common tumor location was the abdomen/pelvis, including four out of ten of those in the umbilical ligament. The most common histological subtype was embryonal rhabdomyosarcoma. Overall survival was 43%. A total of 17 rhabdomyosarcomas in pediatric patients arising in the umbilical ligament were recorded with mean age of diagnosis of 3 years and 4 months. Overall survival was 69%. Costello syndrome is a poorly known disorder in pediatric oncology but their predisposition to malignancies implies the need for a new perspective on early diagnosis and aggressive medical and surgical treatment.

Recombinant growth hormone therapy in a girl with Costello syndrome: a 4-year observation

Background

Costello syndrome is a rare syndrome of multiple congenital anomalies. The typical clinical traits include dysmorphic craniofacial features, skin hyperpigmentation and excess, feeding difficulties leading to severe postnatal growth retardation, short stature, joint hypermobility, and delayed psychomotor development. Additionally, Costello syndrome may present with an increased incidence of congenital heart disease, hypertrophic cardiomyopathy, and increased risk of both benign and malignant tumors. Furthermore, cases of patients with endocrine disorders such as adrenal insufficiency and endogenous growth hormone deficiency have also been documented.

Case presentation

We present a patient with Costello syndrome who has been successfully treated with recombinant human growth hormone (rhGH) for almost 4 years.

Conclusions

The possibility of growth hormone (GH) treatment can be considered in cases of documented GH deficiency in patients with Costello syndrome, but only under close oncologic and cardiologic supervision.

Paternal uniparental disomy 11p15.5 in the pancreatic nodule of an infant with Costello syndrome: Shared mechanism for hyperinsulinemic hypoglycemia in neonates with Costello and Beckwith-Wiedemann syndrome and somatic loss of heterozygosity in Costello syndrome driving clonal expansion

Costello syndrome (CS) entails a cancer predisposition and is caused by activating HRAS mutations, typically arising de novo in the paternal germline. Hypoglycemia is common in CS neonates. A previously reported individual with the rare HRAS p.Gln22Lys had hyperinsulinemic hypoglycemia. Autopsy showed a discrete pancreatic nodule. The morphologic and immunohistochemistry findings, including loss of p57(Kip2) protein, were identical to a focal lesion of congenital hyperinsulinism, however, no KCNJ11 or ABCC8 mutation was identified and germline derived DNA showed no alternation of the maternal or paternal 11p15 alleles. Here we report paternal uniparental disomy (pUPD) within the lesion, similar to the pUPD11p15.5 in Beckwith-Wiedemann syndrome (BWS). The similar extent of the pUPD suggests a similar mechanism driving hyperinsulinemia in both conditions. After coincidental somatic LOH and pUPD, the growth promoting effects of the paternally derived HRAS mutation, in combination with the increased function of the adjacent paternally expressed IGF2, may together result in clonal expansion. Although this somatic LOH within pancreatic tissue resulted in hyperinsulinism, similar LOH in mesenchymal cells may drive embryonal rhabdomyosarcoma (ERMS). Interestingly, biallelic IGF2 expression has been linked to rhabdomyosarcoma tumorigenesis and pUPD11 occurred in all 8 ERMS samples from CS individuals. Somatic KRAS and HRAS mutations occur with comparable frequency in isolated malignancies. Yet, the malignancy risk in CS is notably higher than in Noonan syndrome with a KRAS mutation. It is conceivable that HRAS co-localization with IGF2 and the combined effect of pUPD 11p15.5 on both genes contributes to the oncogenic potential.

Costello syndrome: a Ras/mitogen activated protein kinase pathway syndrome (rasopathy) resulting from HRAS germline mutations

Costello syndrome (OMIM# 218040) is a distinctive rare multisystem disorder comprising a characteristic coarse facial appearance, intellectual disabilities, and tumor predisposition. Although the diagnosis can be suspected clinically, confirmation requires identification of a heterozygous mutation in the proto-oncogene HRAS. In contrast to somatic oncogenic mutations in neoplasia, the Costello syndrome changes are typically introduced in the paternal germline. The predicted amino acid substitutions allow for constitutive or prolonged activation of the HRAS protein, resulting in dysregulation of the Ras/mitogen activated protein kinase pathway. Dysregulation of this signaling pathway is the disease mechanism shared among Costello syndrome and other rasopathies, including neurofibromatosis type 1, Noonan syndrome, cardio-facio-cutaneous syndrome, and Legius syndrome. The Ras/mitogen activated protein kinase pathway governs cell proliferation and differentiation, and its dysregulation affects cardiac and brain development, accounting for the significant overlap in physical and developmental differences and common medical problems among rasopathies. Unlike the genetically heterogeneous Noonan syndrome and cardio-facio-cutaneous syndrome, Costello syndrome is caused by HRAS mutations only. Patients, clinicians, and researchers may benefit from a multidisciplinary "rasopathy clinic," which serves patients with more common conditions such as Noonan syndrome and neurofibromatosis and those affected by rare conditions such as Costello syndrome.

Noonan, Costello and cardio–facio–cutaneous syndromes: dysregulation of the Ras–MAPK pathway

A class of developmental disorders caused by dysregulation of the Ras-induced mitogen-activated protein kinase (MAPK) cascade (the Ras–MAPK pathway) has emerged. Three of these disorders – Noonan, Costello and cardio–facio–cutaneous syndromes – have overlapping phenotypic features characterised by distinctive facial dysmorphia, cardiac defects, musculoskeletal and cutaneous abnormalities, and neurocognitive delay. The germline mutations associated with these disorders are in genes that encode proteins of the Ras–MAPK pathway. In vitro studies have determined that the overwhelming majority of these mutations result in increased signal transduction down the pathway, but usually to a lesser degree than somatic mutations in the same genes that are associated with cancer. The Ras–MAPK pathway is essential in the regulation of the cell cycle, differentiation, growth and senescence, so it is not surprising that germline mutations that affect its function have profound effects on development. Here we review the clinical consequences of the known molecular lesions associated with Noonan syndrome, Costello syndrome and cardio–facio–cutaneous syndrome, and explore possible therapeutic modalities for treatment.

Congenital ulcerating hemangioma in a baby with KRAS mutation and cardio-facio-cutaneous syndrome

CFC syndrome is a genetically heterogenous condition. Missense mutations have been identified in BRAF, KRAS, MEK1 and MEK2. We have reported here a KRAS mutation in a baby girl with an early clinical diagnosis of CFC syndrome associated with a large ulcerating hemangioma. Although ectodermal abnormalities have been described in all individuals with this condition, features such as ichthyosis and hemangioma have been previously found only in those patients carrying a mutation in BRAF, and not in KRAS. The findings we have described contrast with these observations. The relatively high frequency of hemangiomas in CFC syndrome suggests that defects in the expression of the MAPK pathway may alter endothelial cell proliferation. Increased understanding of how the molecular pathways with which defects in CFC syndrome predispose affected individuals to hemangiomas might offer insights into the pathogenesis of this common childhood tumour in the general population.

HRAS and the Costello syndrome

Costello syndrome (CS) is a complex developmental disorder involving characteristic craniofacial features, failure to thrive, developmental delay, cardiac and skeletal anomalies and a predisposition to develop neoplasia, both benign and malignant. CS is caused by activating germline mutations in HRAS and belongs to an exciting class of genetic syndromes that are caused by perturbation of function through the Ras pathway. Some of these other syndromes include Noonan syndrome, LEOPARD syndrome, neurofibromatosis 1 and cardio-facio-cutaneous syndrome. Ras is a critical signaling hub in the cell and is activated by receptor tyrosine kinases, G-protein-coupled receptors, cytokine receptors and extracellular matrix receptors. The downstream effectors of Ras are many and control vital cellular functions including cell cycle progression, cell survival, motility, transcription, translation and membrane trafficking. Understanding the genetic etiology of CS is the first step in gaining insight to the role Ras plays in human development, cellular signaling and cancer pathogenesis.

Hepatoblastoma and heart transplantation in a patient with cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous syndrome (CFC) and Costello syndrome (CS) are disorders with an overlapping spectrum of congenital anomalies. Mutations in the RAS-MAPK pathway have recently been reported in both of these syndromes, with HRAS mutations characteristic for CS and BRAF and MEK1/2 mutations for CFC. We report on a 3-year-old boy who underwent a cardiac transplant at age 8 months for hypertrophic cardiomyopathy; he was subsequently suspected to have CS. At age 35 months he presented with an intra-cardiac mass that was diagnosed as metastatic hepatoblastoma. Although hepatoblastoma is not known to have an increased frequency in immunocompromised patients, questions were raised as whether the post-transplant immuno-suppressive therapy played a role in tumor development. The patient died shortly thereafter and his post-mortem DNA analysis revealed a MEK1 mutation (Y130C) previously reported in CFC. While CS is associated with increased cancer risk, only a single case of leukemia has been reported in a patient with CFC, making this the first case of a solid tumor reported in a patient with CFC.

Uniparental disomy at chromosome 11p15.5 followed by HRAS mutations in embryonal rhabdomyosarcoma: lessons from Costello syndrome

Costello syndrome (CS; MIM 218040) is characterized by short stature, facial dysmorphism, cardiac defects and predisposition to embryonal rhabdomyosarcoma (CS/ERMS) and other neoplasias. CS is caused by germline mutations in the HRAS gene on chromosome 11p15.5, a region showing allelic imbalances in sporadic ERMS and CS/ERMS. The critical gene for ERMS development in this region is unknown. The association of CS and ERMS as well as previous reports illustrating that somatic HRAS mutations are found in a proportion of these tumors prompted us to clarify the significance and a possible correlation of HRAS mutations and genomic rearrangements at 11p15.5 in sporadic ERMS. We screened for somatic HRAS mutations and 11p15.5 imbalances in six sporadic ERMS samples. This analysis uncovered five ERMS samples with uniparental disomy (UPD) at the HRAS locus, two of which harbored HRAS mutations. By analyzing informative genetic variations in or at the HRAS gene locus, we show that one HRAS allele is entirely lost in specimens with UPD at 11p15.5. Notably, in both cases with UPD and HRAS mutations these mutations were heterozygous. Therefore, they must have succeeded the emergence of UPD. In contrast, HRAS germline mutations are the first step in CS/ERMS. Subsequent development of UPD at 11p15.5 may explain previous observations that CS/ERMS express mutant HRAS only. These data implicate that in sporadic ERMS, UPD at 11p15.5 is not driven by HRAS mutations and that imbalances at 11p15.5 and HRAS mutations represent independent but cooperating events during ERMS development.

Costello syndrome and hyperinsulinemic hypoglycemia

Costello syndrome is characterized by mental retardation, loose skin, coarse facies, skeletal abnormalities, cardiovascular abnormalities (congenital heart defects, cardiomyopathy, rhythm disturbances), and predisposition to neoplasia. Endocrine abnormalities including growth hormone deficiency, adrenal insufficiency, glucose intolerance, parathyroid adenoma with hyperprolactinemia and hypoglycemia have been described. Hypoglycemia has been documented due to growth hormone and cortisol deficiency. We report on two patients with Costello syndrome and persistent hyperinsulinemic hypoglycemia and review the endocrine manifestations of Costello syndrome. Both patients required diazoxide therapy to stop the unregulated insulin secretion and maintain normoglycemia. The mechanism of persistent hyperinsulinism in patients with Costello syndrome is unclear.

Paternal bias in parental origin ofHRASmutations in Costello syndrome

Costello syndrome (CS) is a rare congenital condition caused by heterozygous de novo missense mutations affecting the codon for glycine 12 or 13 of the HRAS gene. We have identified 39 CS patients harboring the p.Gly12Ser mutation (NM_005343.2:c.34 G > A), two patients with c.35G > C mutations resulting in p.Gly12Ala substitutions, and one patient carrying the p.Gly13Cys substitution (c.37G > A). We analyzed the region flanking the mutated sites in 42 probands and 59 parents, and used four polymorphic markers to trace the parental origin of the germline mutations: one highly polymorphic hexanucleotide (GGGCCT) repeat region, defining three alleles with different numbers of repeat units (two, three, or four), and three SNPs. One of the SNPs, rs12628 (c.81T > C), was found in strong linkage disequilibrium with the hexanucleotide repeat region. Out of a total of 24 probands with polymorphic markers, 16 informative families were tested and the paternal origin of the germline mutation was found in 14 CS probands; a distribution that is neither consistent with an equal likelihood of mutations arising in either parent (P = 0.0018), nor with exclusive paternal origin.

HRAS mutations in Costello syndrome: detection of constitutional activating mutations in codon 12 and 13 and loss of wild-type allele in malignancy

Costello syndrome (CS) is a complex developmental disorder involving characteristic craniofacial features, failure to thrive, developmental delay, cardiac and skeletal anomalies, and a predisposition to develop neoplasia. Based on similarities with other cancer syndromes, we previously hypothesized that CS is likely due to activation of signal transduction through the Ras/MAPK pathway [Tartaglia et al., 2003]. In this study, the HRAS coding region was sequenced for mutations in a large, well-characterized cohort of 36 CS patients. Heterogeneous missense point mutations predicting an amino acid substitution were identified in 33/36 (92%) patients. The majority (91%) had a 34G --> A transition in codon 12. Less frequent mutations included 35G --> C (codon 12) and 37G --> T (codon 13). Parental samples did not have an HRAS mutation supporting the hypothesis of de novo heterogeneous mutations. There is phenotypic variability among patients with a 34G --> A transition. The most consistent features included characteristic facies and skin, failure to thrive, developmental delay, musculoskeletal abnormalities, visual impairment, cardiac abnormalities, and generalized hyperpigmentation. The two patients with 35G --> C had cardiac arrhythmias whereas one patient with a 37G --> T transversion had an enlarged aortic root. Of the patients with a clinical diagnosis of CS, neoplasia was the most consistent phenotypic feature for predicating an HRAS mutation. To gain an understanding of the relationship between constitutional HRAS mutations and malignancy, HRAS was sequenced in an advanced biphasic rhabdomyosarcoma/fibrosarcoma from an individual with a 34G --> A mutation. Loss of the wild-type HRAS allele was observed, suggesting tumorigenesis in CS patients is accompanied by additional somatic changes affecting HRAS. Finally, due to phenotypic overlap between CS and cardio-facio-cutaneous (CFC) syndromes, the HRAS coding region was sequenced in a well-characterized CFC cohort. No mutations were found which support a distinct genetic etiology between CS and CFC syndromes.

Tumor predisposition in Costello syndrome

Costello syndrome (CS) is a rare congenital anomaly syndrome. Although it may be classified as an "overgrowth" syndrome due to slightly increased birth weight and relative macrocephaly, it is characterized by severe postnatal failure to thrive and short stature. Patients with CS have an increased risk for malignant tumors, a hallmark of several model overgrowth syndromes. The most common tumor in CS is rhabdomyosarcoma (RMS), followed by neuroblastoma and bladder carcinoma. The occurrence of bladder carcinoma in adolescents is distinctly unusual as this is typically a neoplasm of older adults and is not seen with increased frequency in other tumor predisposition syndromes. The increased tumor frequency in CS led to the proposal of a screening protocol, consisting of abdominal and pelvic ultrasounds, and urine studies for catecholamine metabolites and hematuria. It has since become apparent that patients with CS have an increased excretion of catecholamine metabolites in urine without the presence of an identifiable catecholamine secreting tumor. Thus, the urine assay for catecholamines is unhelpful as a screening test for neuroblastoma and should not be used in this population. The benefit of abdominal and pelvic ultrasound and urinalysis for hematuria as screening tests remains to be shown. A timely diagnosis of CS is a necessary prerequisite for awareness of the increased tumor risk. Once a malignancy has been identified, treatment should follow standard protocols. Additional medical problems characteristic for CS, such as hypertrophic cardiomyopathy and arrhythmia, need to be considered and addressed appropriately.

HRAS mutation analysis in Costello syndrome: Genotype and phenotype correlation

Costello syndrome is a rare condition comprising mental retardation, distinctive facial appearance, cardiovascular abnormalities (typically pulmonic stenosis, hypertrophic cardiomyopathy, and/or atrial tachycardia), tumor predisposition, and skin and musculoskeletal abnormalities. Recently mutations in HRAS were identified in 12 Japanese and Italian patients with clinical information available on 7 of the Japanese patients. To expand the molecular delineation of Costello syndrome, we performed mutation analysis in 34 North American and 6 European (total 40) patients with Costello syndrome, and detected missense mutations in HRAS in 33 (82.5%) patients. All mutations affected either codon 12 or 13 of the protein product, with G12S occurring in 30 (90.9%) patients of the mutation-positive cases. In two patients, we found a mutation resulting in an alanine substitution in position 12 (G12A), and in one patient, we detected a novel mutation (G13C). Five different HRAS mutations have now been reported in Costello syndrome, however genotype-phenotype correlation remains incomplete.

Disruption of the PDGFB gene in a 1;22 translocation patient does not cause Costello syndrome

We studied a female patient initially diagnosed with Costello syndrome who carries an apparently balanced translocation, t(1;22) (q24.3;q13.1). Molecular characterization of the translocation revealed a mosaic of two derivative chromosomes 1 in her peripheral blood lymphocytes, in one of which the coding region of the platelet-derived growth factor (PDGFB; chromosome 22q13.1) gene was disrupted. Both the initial translocation and the secondary intrachromosomal rearrangement appear to have occurred by nonhomologous (illegitimate) recombination. In 18 patients with Costello syndrome, mutation analysis of the genes belonging to the PDGF/R family, PDGFA, PDGFB, PDGFC, PDGFD, PDGFRA, and PDGFRB, revealed no pathogenic mutations. Reevaluation of the clinical symptoms of the translocation patient challenges the diagnosis of Costello syndrome in this patient. In total RNA isolated from lymphocytes of the translocation patient, we identified four different fusion transcripts consisting of PDGFB exons and parts of chromosome 1q24.3. In two of the mRNAs, exon 6 of PDGFB, encoding the 41 C-terminal amino acid residues, was absent. Immunofluorescence analysis showed that the wild-type protein was dispersed and formed a network-like structure in the extracellular matrix, whereas the two aberrant PDGFB proteins were localized in aggregates. We speculate that the biological consequences of the mutant PDGFB allele contributed to the unique disease phenotype of the translocation patient.

Epidemiology and genetics of childhood cancer

Childhood cancer is rare everywhere in the world, with age-standardized annual incidence usually between 70 and 160 per million at age 0-14 years. Greater variation is seen between populations for some specific tumour types. Some of the largest variations are geographical and are attributable to environmental factors, whereas variation mainly on ethnic lines seems likely to be a marker of genetic predisposition. A wide range of familial and genetic syndromes is associated with an increased risk of childhood cancer. Virtually all the excess risk of cancer among first-degree relatives of children with cancer can be accounted for by known hereditary syndromes. Studies of weak predisposition and gene-environment interaction have so far shown limited consistency. There are very few established environmental or exogenous risk factors and most of these are infective agents. Many putative risk factors can hardly ever be investigated epidemiologically except by interview or questionnaire studies. Some recent examples illustrate the continuing problems of participation bias and recall bias.