Further delineation of cardiac abnormalities in Costello syndrome

Progress of Pathogenesis in Pediatric Multifocal Atrial Tachycardia

Multifocal atrial tachycardia (MAT) is defined as irregular P-P, R-R, and P-R intervals, isoelectric baseline between P waves, and ventricular rate over 100 beats/min. Although the prognosis of pediatric MAT in most patients is favorable, adverse outcomes of MAT have been reported, such as cardiogenic death (3%), respiratory failure (6%), or persistent arrhythmia (7%), due to delayed diagnosis and poorly controlled MAT. Previous studies demonstrated that pediatric MAT is associated with multiple enhanced automatic lesions located in the atrium or abnormal automaticity of a single lesion located in the pulmonary veins via multiple pathways to trigger electrical activity. Recent studies indicated that pediatric MAT is associated with the formation of a re-entry loop, abnormal automaticity, and triggering activity. The occurrence of pediatric MAT is affected by gestational disease, congenital heart disease, post-cardiac surgery, pulmonary hypertension, and infectious diseases, which promote MAT via inflammation, redistribution of the autonomic nervous system, and abnormal ion channels. However, the pathogenesis of MAT needs to be explored. This review is aimed to summarize and analyze the pathogenesis in pediatric MAT.

Hyperinsulinemic Hypoglycemia in a Patient with Costello Syndrome: An Etiology to Consider in Hypoglycemia

Several endocrine disorders have been defined in patients with Costello syndrome (CS). In this report, we describe a patient with CS accompanied by a clinical picture of hyperinsulinemic hypoglycemia responsive to diazoxide treatment. A 41-day-old female patient with a birth weight of 3,600 g was referred for atypical facial features and swallowing dysfunction. She had a weight of 4,000 g (-0.8 SDS), a length of 50 cm (-2.4 SDS), and a head circumference of 38 cm (0.2 SDS). The clinical findings were suggestive of a genetic syndrome, mainly a RASopathy or Beckwith-Wiedemann syndrome. Whole exome sequencing revealed a de novo heterozygous missense variant in the HRAS (NM_001130442) gene in exon 2: c.35G>C; p.(Gly12Ala), establishing the molecular diagnosis of CS. The patient developed symptomatic hypoglycemia (jitteriness and sweating) at the age of 13 months. The patient's serum glucose was 38 mg/dL with simultaneous serum insulin and C-peptide levels, 2.8 μIU/mL and 1.8 ng/mL, respectively. Hyperinsulinism was suspected, and an exaggerated glucose response was detected in a glucagon test. Blood glucose monitoring indicated episodes of fasting hypoglycemia and postprandial hyperglycemia. Diazoxide of 10 mg/kg/day was initiated in 3 doses for hyperinsulinemic hypoglycemia, which resolved without new episodes of postprandial hyperglycemia. The patient deceased at the age of 17 months due to cardiorespiratory failure in the course of severe pneumonia complicated with pulmonary hypertension and hypertrophic cardiomyopathy. Several genetic syndromes including CS are associated with endocrinologic manifestations including abnormal glucose homeostasis. Although the frequency and underlying mechanisms leading to hyperinsulinemic hypoglycemia are yet unknown, hypoglycemia in CS responds well to diazoxide.

Neonatal cardiac hypertrophy: the role of hyperinsulinism-a review of literature

Hypertrophic cardiomyopathy (HCM) in neonates is a rare and heterogeneous disorder which is characterized by hypertrophy of heart with histological and functional disruption of the myocardial structure/composition. The prognosis of HCM depends on the underlying diagnosis. In this review, we emphasize the importance to consider hyperinsulinism in the differential diagnosis of HCM, as hyperinsulinism is widely associated with cardiac hypertrophy (CH) which cannot be distinguished from HCM on echocardiographic examination. We supply an overview of the incidence and treatment strategies of neonatal CH in a broad spectrum of hyperinsulinemic diseases. Reviewing the literature, we found that CH is reported in 13 to 44% of infants of diabetic mothers, in approximately 40% of infants with congenital hyperinsulinism, in 61% of infants with leprechaunism and in 48 to 61% of the patients with congenital generalized lipodystrophy. The correct diagnosis is of importance since there is a large variation in prognoses and there are various strategies to treat CH in hyperinsulinemic diseases.Conclusion: The relationship between CH and hyperinsulism has implications for clinical practice as it might help to establish the correct diagnosis in neonates with cardiac hypertrophy which has both prognostic and therapeutic consequences. In addition, CH should be recognized as a potential comorbidity which might necessitate treatment in all neonates with known hyperinsulinism.What is Known:• Hyperinsulinism is currently not acknowledged as a cause of hypertrophic cardiomyopathy (HCM) in textbooks and recent Pediatric Cardiomyopathy Registry publications.What is New:• This article presents an overview of the literature of hyperinsulinism in neonates and infants showing that hyperinsulinism is associated with cardiac hypertrophy (CH) in a broad range of hyperinsulinemic diseases.• As CH cannot be distinguished from HCM on echocardiographic examination, we emphasize the importance to consider hyperinsulinism in the differential diagnosis of HCM/CH as establishing the correct diagnosis has both prognostic and therapeutic consequences.

Medically actionable comorbidities in adults with Costello syndrome

Costello syndrome (CS) is an autosomal-dominant condition caused by activating missense mutations in HRAS. There is little literature describing health concerns specific to adults with CS. Parents of individuals with CS need to know what to anticipate as their children age. We surveyed a group of 20 adults and older adolescents with CS regarding their medical concerns and lifestyle characteristics. We identified several previously undescribed actionable medical concerns in adults with CS. First, the high prevalence of anxiety in this cohort indicates that screening for anxiety is warranted since this is a treatable condition that can have a significant impact on quality of life. Second, adults with CS should be monitored for progressive contractures or other problems that could decrease mobility. This is especially important in a population that seems to have increased risk for osteopenia. Finally, the lack of cancer diagnoses in adulthood is of interest, although the cohort is too small to draw definitive conclusions about cancer risk in adults with CS. Ongoing follow-up of the current cohort of adults with CS is necessary to delineate progressive medical and physical problems, which is essential for providing targeted management recommendations and anticipatory guidance to families.

Phenotypic and Genetic Characteristics of Five Korean Patients with Costello Syndrome

Costello syndrome (CS) is a rare genetic disorder characterized by distinctive facial appearance, cardiopulmonary complications, severe growth retardation, skin and skeletal defects, developmental delay, and tumor predisposition. CS is caused by heterozygous de novo mutations in the proto-oncogene HRAS, which is a component of the RAS/mitogen-activated protein kinase pathway. Herein, we reviewed the phenotypic and genetic features of 5 Korean patients who were genetically diagnosed with CS. Atrial tachycardia and polyhydramnios, which are important prenatal features for CS, were observed in 4 and 5 patients, respectively. The distinctive coarse facial appearances of the patients and presence of deep palmoplantar creases supported the clinical diagnosis of CS, which was confirmed by HRAS sequence analysis. Extremely poor postnatal growth was observed in all 5 patients. Further, all patients exhibited cardiac abnormalities; left ventricular hypertrophy and hypertrophic cardiomyopathy were observed in 3 patients. All 5 patients suffered from airway problems; 3 of them required intubation right after birth, and 2 of them received tracheostomy. One patient with a p.Gly12Ser mutation was diagnosed with retroperitoneal rhabdomyosarcoma alveolar type at the age of 5 years. Consistent with previous reports, both patients with p.Gly12Cys mutations died within the first year of life due to cardiopulmonary failure. Our study summarizes the characteristics of these 5 Korean patients with CS and, along with previous studies, provides clues for genotype-phenotype correlation in patients with CS.

A system-based approach to the genetic etiologies of non-immune hydrops fetalis

A wide spectrum of genetic causes may lead to nonimmune hydrops fetalis (NIHF), and a thorough phenotypic and genetic evaluation are essential to determine the underlying etiology, optimally manage these pregnancies, and inform discussions about anticipated prognosis. In this review, we outline the known genetic etiologies of NIHF by fetal organ system affected, and provide a systematic approach to the evaluation of NIHF. Some of the underlying genetic disorders are associated with characteristic phenotypic features that may be seen on prenatal ultrasound, such as hepatomegaly with lysosomal storage disorders, hyperechoic kidneys with congenital nephrosis, or pulmonary valve stenosis with RASopathies. However, this is not always the case, and the approach to evaluation must include prenatal ultrasound findings as well as genetic testing and many other factors. Genetic testing that has been utilized for NIHF ranges from standard chromosomal microarray or karyotype to gene panels and broad approaches such as whole exome sequencing. Family and obstetric history, as well as pathology examination, can yield additional clues that are helpful in establishing a diagnosis. A systematic approach to evaluation can guide a more targeted approach to genetic evaluation, diagnosis, and management of NIHF.

Retinal dystrophy in two boys with Costello syndrome due to the HRAS p.Gly13Cys mutation

Features of Costello Syndrome, a systemic disorder caused by germline mutations in the proto-oncogene HRAS from the RAS/MAPK pathway, include failure-to-thrive, short stature, coarse facial features, cardiac defects including hypertrophic cardiomyopathy, intellectual disability, and predisposition to neoplasia. Two unrelated boys with Costello syndrome and an HRAS mutation (p.Gly13Cys) are presented with their ophthalmologic findings. Both had early symptoms of nystagmus, photophobia, and vision abnormalities. Fundus examination findings of retinal dystrophy were present at age 3 years. Both boys have abnormal electroretinograms with reduced or undetectable rod responses along with reduced cone responses consistent with rod-cone dystrophy. Our observations suggest that early ophthalmic examination and re-evaluations are indicated in children with Costello syndrome.

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.

Novel pathogenic variant in the HRAS gene with lethal outcome and a broad phenotypic spectrum among Polish patients with Costello syndrome

Costello syndrome (CS) is a rare congenital disorder from the group of RASopathies, characterized by a distinctive facial appearance, failure to thrive, cardiac and skin anomalies, intellectual disability, and a predisposition to neoplasia. CS is associated with germline mutations in the proto-oncogene HRAS, a small GTPase from the Ras family. In this study, a molecular and clinical analysis was carried out in eight Polish patients with the Costello phenotype. A molecular test showed two known heterozygous mutations in the first coding exon of the gene in seven patients: p.G12S (n=4) and p.G12A (n=3), and a novel pathogenic variant p.G60V in one child with an unusually severe, lethal course of the syndrome. In addition, a fatal course of CS was present in one patient with the p.G12A mutation and in another with p.G12S, there was a co-occurrence of Turner syndrome because of the distal Xp deletion. A severe clinical manifestation with a lethal outcome in an individual with p.G60V in HRAS and contrary observations of an attenuated phenotype in CS patients with other mutations at glycine-60 residue may suggest that the nature of the substituted amino acid plays a significant role in the clinical variability observed in some CS cases.

Genetic testing in congenital heart disease: A clinical approach

Congenital heart disease (CHD) is the most common type of birth defect. Traditionally, a polygenic model defined by the interaction of multiple genes and environmental factors was hypothesized to account for different forms of CHD. It is now understood that the contribution of genetics to CHD extends beyond a single unified paradigm. For example, monogenic models and chromosomal abnormalities have been associated with various syndromic and non-syndromic forms of CHD. In such instances, genetic investigation and testing may potentially play an important role in clinical care. A family tree with a detailed phenotypic description serves as the initial screening tool to identify potentially inherited defects and to guide further genetic investigation. The selection of a genetic test is contingent upon the particular diagnostic hypothesis generated by clinical examination. Genetic investigation in CHD may carry the potential to improve prognosis by yielding valuable information with regards to personalized medical care, confidence in the clinical diagnosis, and/or targeted patient follow-up. Moreover, genetic assessment may serve as a tool to predict recurrence risk, define the pattern of inheritance within a family, and evaluate the need for further family screening. In some circumstances, prenatal or preimplantation genetic screening could identify fetuses or embryos at high risk for CHD. Although genetics may appear to constitute a highly specialized sector of cardiology, basic knowledge regarding inheritance patterns, recurrence risks, and available screening and diagnostic tools, including their strengths and limitations, could assist the treating physician in providing sound counsel.

Cardiac events in Costello syndrome: One case and a review of the literature

Costello syndrome is a rare syndrome associated with de novo mutations in the HRAS gene. It is mostly revealed during in the first months of life by growth retardation, facial dysmorphic features, skin and cardiac abnormalities and subsequent cognitive deficit of varying severity. We report a case of Costello syndrome in a 3-month-old infant. The initial cardiac investigations were normal except frequent premature atrial complexes. After few months, worsening arrhythmia with bursts of ventricular tachycardia were noted as well as the secondary progressive obstructive left ventricular hypertrophic cardiomyopathy (HCM). Cardiac involvement is determinant for the prognosis of Costello syndrome. It frequently consists of hypertrophic cardiomyopathy (one third of patients), with involvement of the left ventricle in half of the cases. It is often asymmetrical and associated with obstruction of the outflow recalling family hypertrophic cardiomyopathy. The natural history of HCM in Costello syndrome and its management remains poorly known because of paucity of reported cases. Progression of the HCM can be very rapid like the reported case. On the other hand, the spontaneous regression of the HCM in some patients has been reported. In addition, cardiac threatening arrhythmias may be noted. So that, cardiac assessment and monitoring with regular echocardiography and electrocardiogram follow up is mandatory.

Cutaneous manifestations in Costello and cardiofaciocutaneous syndrome: report of 18 cases and literature review

Costello syndrome (CS) and cardiofaciocutaneous syndrome (CFCS) are congenital disorders involving the Ras-MAPK pathway with phenotypic overlap. These two entities are thought to share common cutaneous findings, although so far they have been poorly studied. The objective of this prospective observational study was to describe the spectrum of skin findings in CS and CFCS and to highlight those specific to each of these two diseases. Patients with a confirmed diagnosis of CFCS or CS underwent a systematic skin examination during the annual workshop organized by the French CS association in 2007 and 2009 in Bordeaux, France. Eighteen patients were included in the study. Specific skin abnormalities, including cutis laxa, curly hair, pruritus, and hyperhidrosis, are shared by CFCS and CS, whereas others may help to differentiate between these two syndromes. Acanthosis nigricans, papillomas, and loose thick skin of the dorsum of the hands are characteristic of CS, whereas sparse eyebrows and dry hyperkeratotic skin are suggestive of CFCS. Our results highlight that a systematic cutaneous examination, in addition to dysmorphologic and noncutaneous anomalies, may be helpful in establishing the diagnosis of CFCS and CS. The physiopathologic link between constitutional Ras-MAPK pathway activation and the observed ectodermal findings remains to be investigated.

Noonan syndrome

Noonan syndrome is a genetic multisystem disorder characterised by distinctive facial features, developmental delay, learning difficulties, short stature, congenital heart disease, renal anomalies, lymphatic malformations, and bleeding difficulties. Mutations that cause Noonan syndrome alter genes encoding proteins with roles in the RAS-MAPK pathway, leading to pathway dysregulation. Management guidelines have been developed. Several clinically relevant genotype-phenotype correlations aid risk assessment and patient management. Increased understanding of the pathophysiology of the disease could help development of pharmacogenetic treatments.

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.

New Genetic Insights into Congenital Heart Disease

There has been remarkable progress in understanding the genetic basis of cardiovascular malformations. Chromosome microarray analysis has provided a new tool to understand the genetic basis of syndromic cardiovascular malformations resulting from microdeletion or microduplication of genetic material, allowing the delineation of new syndromes. Improvements in sequencing technology have led to increasingly comprehensive testing for aortopathy, cardiomyopathy, single gene syndromic disorders, and Mendelian-inherited congenital heart disease. Understanding the genetic etiology for these disorders has improved their clinical recognition and management and led to new guidelines for treatment and family-based diagnosis and surveillance. These new discoveries have also expanded our understanding of the contribution of genetic variation, susceptibility alleles, and epigenetics to isolated congenital heart disease. This review summarizes the current understanding of the genetic basis of syndromic and non-syndromic congenital heart disease and highlights new diagnostic and management recommendations.

Ross operation in a neuro-cardio-facial-cutaneous syndrome patient

Congenital heart diseases are a major part of Costello and cardio-facio-cutaneous syndromes. Subaortic stenosis was reported rarely and Ross operation never in these syndromes.

We reported a girl patient whose manifestations were consistent with these syndromes. Distinction between these syndromes was not possible as genetic testing was not carried out. She developed severe neoaortic regurgitation 2.5 years after the Ross operation and died due to the complications of aortic valve replacement.

Ross operation may be an unsuitable option in these syndromes due to the possibility of subtle pulmonic valve pathology.

[Neonatal atrial tachycardia: suggestive clinical sign of Costello syndrome]

Costello syndrome is a rare association of symptoms caused by de novo germline mutations of the HRAS oncogene interfering in the RAS/mitogen-activated protein kinase (MAPK) signal transduction pathway. Mutations in this pathway are also responsible for Noonan syndrome and the related cardiofaciocutaneous syndrome (CFC) as well as LEOPARD syndrome. The 4 syndromes share phenotypic resemblances concerning patients' morphology but also regarding associated cardiac disease, namely hypertrophic cardiomyopathy, pulmonary stenosis, and atrial septal defect. The electrocardiogram often shows an upper deviation of the QRS axis. Arrhythmias are rare but, if present, are particularly typical of CS. We describe herein two newborn infants with Costello syndrome revealed by atrial tachycardia associated with characteristic morphological and cardiac features of syndromes related to mutations in the RAS/MAPK pathway.

Phenotypic analysis of individuals with Costello syndrome due to HRAS p.G13C

Costello syndrome is characterized by severe failure-to-thrive, short stature, cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic cardiomyopathy (HCM)), distinctive facial features, a predisposition to papillomata and malignant tumors, postnatal cerebellar overgrowth resulting in Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the glycine residues in position 12 or 13, and more than 80% of patients share p.G12S. To test the hypothesis that subtle genotype-phenotype differences exist, we report the first cohort comparison between 12 Costello syndrome individuals with p.G13C and individuals with p.G12S. The individuals with p.G13C had many typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly with posterior fossa crowding, and developmental delay. Subjectively, their facial features were less coarse. Statistically significant differences included the absence of multifocal atrial tachycardia (P-value = 0.033), ulnar deviation of the wrist (P < 0.001) and papillomata (P = 0.003), and fewer neurosurgical procedures (P = 0.024). Fewer individuals with p.G13C had short stature (height below -2 SD) without use of growth hormone (P < 0.001). The noteworthy absence of malignant tumors did not reach statistical significance. Novel ectodermal findings were noted in individuals with p.G13C, including loose anagen hair resulting in easily pluckable hair with a matted appearance, different from the tight curls typical for most Costello syndrome individuals. Unusually long eye lashes requiring trimming are a novel finding we termed dolichocilia. These distinctive ectodermal findings suggest a cell type specific effect of this particular mutation. Additional patients are needed to validate these findings.

Clinical, pathological, and molecular analyses of cardiovascular abnormalities in Costello syndrome: a Ras/MAPK pathway syndrome

Cardiovascular abnormalities are important features of Costello syndrome and other Ras/MAPK pathway syndromes ("RASopathies"). We conducted clinical, pathological and molecular analyses of 146 patients with an HRAS mutation including 61 enrolled in an ongoing longitudinal study and 85 from the literature. In our study, the most common (84%) HRAS mutation was p.G12S. A congenital heart defect (CHD) was present in 27 of 61 patients (44%), usually non-progressive valvar pulmonary stenosis. Hypertrophic cardiomyopathy (HCM), typically subaortic septal hypertrophy, was noted in 37 (61%), and 5 also had a CHD (14% of those with HCM). HCM was chronic or progressive in 14 (37%), stabilized in 10 (27%), and resolved in 5 (15%) patients with HCM; follow-up data was not available in 8 (22%). Atrial tachycardia occurred in 29 (48%). Valvar pulmonary stenosis rarely progressed and atrial septal defect was uncommon. Among those with HCM, the likelihood of progressing or remaining stable was similar (37%, 41% respectively). The observation of myocardial fiber disarray in 7 of 10 (70%) genotyped specimens with Costello syndrome is consistent with sarcomeric dysfunction. Multifocal atrial tachycardia may be distinctive for Costello syndrome. Potentially serious atrial tachycardia may present in the fetus, and may continue or worsen in about one-fourth of those with arrhythmia, but is generally self-limited in the remaining three-fourths of patients. Physicians should be aware of the potential for rapid development of severe HCM in infants with Costello syndrome, and the need for cardiovascular surveillance into adulthood as the natural history continues to be delineated.

High incidence of progressive postnatal cerebellar enlargement in Costello syndrome: brain overgrowth associated with HRAS mutations as the likely cause of structural brain and spinal cord abnormalities

Costello syndrome is a rasopathy caused by germline mutations in the proto-oncogene HRAS. Its presentation includes failure-to-thrive with macrocephaly, characteristic facial features, hypertrophic cardiomyopathy, papillomata, malignant tumors, and cognitive impairment. In a systematic review we found absolute or relative macrocephaly (100%), ventriculomegaly (50%), and other abnormalities on brain and spinal cord imaging studies in 27/28 individuals. Posterior fossa crowding with cerebellar tonsillar herniation (CBTH) was noted in 27/28 (96%), and in 10/17 (59%) with serial studies posterior fossa crowding progressed. Sequelae of posterior fossa crowding and CBTH included hydrocephalus requiring shunt or ventriculostomy (25%), Chiari 1 malformation (32%), and syrinx formation (25%). Our data reveal macrocephaly with progressive frontal bossing and CBTH, documenting an ongoing process rather than a static congenital anomaly. Comparison of images obtained in young infants to subsequent studies demonstrated postnatal development of posterior fossa crowding. This process of evolving megalencephaly and cerebellar enlargement is in keeping with mouse model data, delineating abnormal genesis of neurons and glia, resulting in an increased number of astrocytes and enlarged brain volume. In Costello syndrome and macrocephaly-capillary malformation syndrome disproportionate brain growth is the main factor resulting in postnatal CBTH and Chiari 1 malformation.

Progressively worsening hypertrophic cardiomyopathy in a child with newly diagnosed Costello syndrome while receiving growth hormone therapy

We describe a 6-year-old boy with newly diagnosed Costello syndrome after the diagnosis of severe hypertrophic cardiomyopathy. His neonatal asymmetric septal cardiomyopathy resolved by 9 months of age but reappeared at 6 years of age. This report highlights two important concepts: the association of genetic syndromes with hypertrophic cardiomyopathy and the possibility of worsening severity of hypertrophic cardiomyopathy linked to growth hormone therapy.

Neuro-kardio-fazio-kutane Syndrome

Neuro-kardio-fazio-kutane („neuro-cardio-facio-cutaneous“: NCFC) Syndrome wurden in den letzten Jahren als eine Gruppe von angeborenen Erkrankungen definiert, deren phänotypische Überschneidungen eine gemeinsame pathogenetische Grundlage haben. Erkrankungen aus diesem phänotypischen Spektrum gehen mit einer Überfunktion des RAS-MAPK-Signalwegs (RAS: „rat sarcoma“, MAPK mitogenaktivierte Proteinkinase) einher. Zu den neuro-kardio-fazio-kutanen Erkrankungen gehören das Noonan-, das LEOPARD-, das kardio-fazio-kutane („cardio-facio-cutaneous“: CFC) und das Costello-Syndrom, die Neurofibromatose Typ 1 sowie das Legius-Syndrom. Für eine sachgerechte medizinische Diagnostik und Behandlung sowie die notwendige psychosoziale Betreuung von Betroffenen und deren Familien ist das Zusammenwirken verschiedener Fachdisziplinen notwendig.

Medical and surgical perspectives of cardiac hypertrophy in Costello syndrome

We describe our experience with 2 patients having Costello syndrome, aged 11 and 36 months, who suffered systolic anterior motion of the aortic leaflet of the mitral valve and obstructive cardiac hypertrophy requiring surgery, comparing their cardiac characteristics to those described previously. We conclude that the heterogeneous nature of the cardiac hypertrophy in this syndrome can be considered and managed as the sum of a diffuse hypertrophy accessible to beta-blockade, and an asymmetric hypertrophy accessible to surgical myomectomy.

Prenatal features of Costello syndrome: ultrasonographic findings and atrial tachycardia

OBJECTIVE

Delineate prenatal features of Costello syndrome (caused by HRAS mutations), which consists of mental retardation, facial, cardiovascular, skin, and musculoskeletal anomalies, and tumor predisposition.

METHODS

Literature and new cases classified as Group I (pre-HRAS), Group II (HRAS confirmed), and Group III (HRAS confirmed in natural history study, plus three contributed cases).

RESULTS

Polyhydramnios occurred in most (mean 79%) pregnancies of cases in Groups I (98), II (107), and III (17); advanced paternal age and prematurity were noted in approximately half. Less frequent were nuchal thickening, ascites, shortened long bones, abnormal hand posture, ventriculomegaly, macrosomia, and macrocephaly. Fetal arrhythmia occurred in nine cases (six supraventricular or unspecified tachycardia, one unspecified arrhythmia, and two premature atrial contractions, PACs); excluding three new cases and two with PACs, the estimated prenatal frequency is 4/222 (2%).

CONCLUSION

Costello syndrome can be suspected prenatally when polyhydramnios is accompanied by nuchal thickening, hydrops, shortened long bones, abnormal hand posture, ventriculomegaly, large size, and macrocephaly, and especially fetal atrial tachycardia. Consideration should be given for timely prenatal diagnostic studies for confirmative HRAS gene mutations and for maternal treatment of serious fetal arrhythmia.

Looking past the lump: genetic aspects of inguinal hernia in children

Inguinal hernia is associated with a multitude of genetic syndromes. Disorders of the microfibril, elastin, collagen, and the glycosaminoglycan component of the extracellular matrix can result in an increase in the likelihood of inguinal hernia. In addition, inguinal hernia may be the presenting feature of disorders of sexual differentiation. Inguinal hernia of unknown etiology also occurs more commonly in several other groups of genetic diseases including chromosomal disorders, microdeletion disorders such as 22q11.2 microdeletion, and in single gene disorders. We review the genetics of connective tissue formation and focus on a series of genetic conditions that may present with or are characterized by a higher risk of inguinal hernia. A comprehensive review of the literature aims to provide a diagnostic framework to aid in the identification of patients with inguinal hernia as part of underlying genetic disease.

Oncogenic HRAS mutations cause prolonged PI3K signaling in response to epidermal growth factor in fibroblasts of patients with Costello syndrome

Costello syndrome (CS) is a rare congenital disorder characterized by failure to thrive, craniofacial dysmorphisms, cardiac and skin abnormalities, mental retardation, and predisposition to malignancies. CS is caused by heterozygous gain-of-function mutations in HRAS that also occur as somatic alterations in human tumors. HRAS is one of the three classical RAS proteins and cycles between an active, GTP- and an inactive, GDP-bound conformation. We used primary human skin fibroblasts from patients with CS as a model system to study the functional consequences of HRAS mutations on endogenous signaling pathways. The GTP-bound form of HRAS was significantly enriched in CS compared with normal fibroblasts. Active HRAS is known to stimulate both the RAF-MEK-ERK and the PI3K-AKT signaling cascade. Phosphorylation of MEK and ERK was normal in CS fibroblasts under basal conditions and slightly prolonged after epidermal growth factor (EGF) stimulation. Interestingly, basal phosphorylation of AKT was increased yet more in CS fibroblasts. Moreover, AKT phosphorylation was diminished in the early and enhanced in the late phase of EGF stimulation. Taken together, these results document that CS-associated HRAS mutations result in prolonged signal flux in a ligand-dependent manner. Our data suggest that altered cellular response to growth factors rather than constitutive activation of HRAS downstream signaling molecules may contribute to some of the clinical features in patients with CS.

Endogenous expression of Hras(G12V) induces developmental defects and neoplasms with copy number imbalances of the oncogene

We developed mice with germline endogenous expression of oncogenic Hras to study effects on development and mechanisms of tumor initiation. They had high perinatal mortality, abnormal cranial dimensions, defective dental ameloblasts, and nasal septal deviation, consistent with some of the features of human Costello syndrome. These mice developed papillomas and angiosarcomas, which were associated with Hras(G12V) allelic imbalance and augmented Hras signaling. Endogenous expression of Hras(G12V) was also associated with a higher mutation rate in vivo. Tumor initiation by Hras(G12V) likely requires augmentation of signal output, which in papillomas and angiosarcomas is achieved via increased Hras-gene copy number, which may be favored by a higher mutation frequency in cells expressing the oncoprotein.

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.

Severe, obstructive biventricular hypertrophy in a patient with Costello syndrome: Clinical impact and management

We report a severe, biventricular obstructive cardiomyopathy in a young female with Costello syndrome, who underwent a right ventricular myectomy for symptoms relief. We discuss potential clinical implications and management of severe hypertrophy in Costello syndrome.

A mouse model for Costello syndrome reveals an Ang II-mediated hypertensive condition

Germline activation of H-RAS oncogenes is the primary cause of Costello syndrome (CS), a neuro-cardio-facio-cutaneous developmental syndrome. Here we describe the generation of a mouse model of CS by introduction of an oncogenic Gly12Val mutation in the mouse H-Ras locus using homologous recombination in ES cells. Germline expression of the endogenous H-RasG12V oncogene, even in homozygosis, resulted in hyperplasia of the mammary gland. However, development of tumors in these mice was rare. H-RasG12V mutant mice closely phenocopied some of the abnormalities observed in patients with CS, including facial dysmorphia and cardiomyopathies. These mice also displayed alterations in the homeostasis of the cardiovascular system, including development of systemic hypertension, extensive vascular remodeling, and fibrosis in both the heart and the kidneys. This phenotype was age dependent and was a consequence of the abnormal upregulation of the renin-Ang II system. Treatment with captopril, an inhibitor of Ang II biosynthesis, prevented development of the hypertension condition, vascular remodeling, and heart and kidney fibrosis. In addition, it partially alleviated the observed cardiomyopathies. These mice should help in elucidating the etiology of CS symptoms, identifying additional defects, and evaluating potential therapeutic strategies.

Adults with genetic syndromes and cardiovascular abnormalities: clinical history and management

Cardiovascular abnormalities, especially structural congenital heart defects, commonly occur in malformation syndromes and genetic disorders. Individuals with syndromes comprise a significant proportion of those affected with selected congenital heart defects such as complete atrioventricular canal, interrupted arch type B, supravalvar aortic stenosis, and pulmonary stenosis. As these individuals age, they contribute to the growing population of adults with special health care needs. Although most will require longterm cardiology follow-up, primary care providers, geneticists, and other specialists should be aware of (1) the type and frequency of cardiovascular abnormalities, (2) the range of clinical outcomes, and (3) guidelines for prospective management and treatment of potential complications. This article reviews fundamental genetic, cardiac, medical, and reproductive issues associated with common genetic syndromes that are frequently associated with a cardiovascular abnormality. New data are also provided about the cardiac status of adults with a 22q11.2 deletion and with Down syndrome.

Costello syndrome: clinical diagnosis in the first year of life

We report on three patients with Costello syndrome (CS) diagnosed during the first year of life and try to outline the clinical characteristics facilitating early recognition of this syndrome, which can now be corroborated by testing the HRAS gene. Phenotypical overlap of CS with Noonan (NS) and cardiofaciocutaneous syndrome (CFCS), particularly in neonatal age, is well known. Diagnostic features useful for recognition of CS in the first year of life are the following: (1) fetal and neonatal macrosomia with subsequent slow growth due to severe feeding difficulties, (2) developmental delay, (3) particularly coarse facial dysmorphisms and gingival hyperplasia, (4) skeletal anomalies as osteoporosis and metaphyseal enlargement, (5) hypertrophic cardiomyopathy (HCM) with asymmetric septal thickening and systolic anterior motion of the mitral valve, and (6) specific atrial arrhythmias. Following a clinical suspect of CS based on specific features, molecular screening of HRAS gene mutations should precede analysis of the other genes in the Ras-MAPK pathway implicated in related disorders with overlapping phenotypes.

Small GTP-binding proteins and their regulators in cardiac hypertrophy

Small GTP-binding proteins (small G proteins) act as GDP-GTP-regulated molecular switches and are activated by guanine nucleotide exchange factors (GEFs) in response to diverse extracellular stimuli. During this last decade, numerous molecular and cellular studies, as well as genetically-modified animal models, have highlighted the role of small G proteins in the regulation of cardiac hypertrophy. The growing interest in small G protein signalling comes from the fact that chronic hypertrophic response is considered maladaptive and predisposes individuals to heart failure. Although some of the hypertrophic signalling pathways involving small G proteins have now been identified, a central question deals with the identity of the GEFs that modulate small G protein activation in the context of cardiac hypertrophy. Here, we discuss the precise regulation of Ras and Rho subfamilies of GTPases by GEFs and other regulatory proteins during cardiac hypertrophy. In addition, we summarize recent published data, mainly those describing the role of small G proteins in the development of myocardial hypertrophy and we further present the importance of their downstream effectors in myocardial remodelling.

Costello syndrome and related disorders

PURPOSE OF REVIEW

Costello syndrome is a rare congenital disorder affecting multiple organ systems, encompassing severe failure to thrive, cardiac anomalies including hypertrophic cardiomyopathy and atrial tachycardia, tumor predisposition, and cognitive impairment. Costello syndrome shares findings with cardio-facio-cutaneous syndrome and the diagnosis can be challenging. The discovery of gene mutations underlying these and other closely related disorders allows for molecular confirmation of a clinical diagnosis.

RECENT FINDINGS

The identification of germline HRAS mutations in Costello syndrome, and mutations in BRAF, MEK1 and MEK2 in cardio-facio-cutaneous syndrome, uncovered the biologic mechanism for the shared phenotypic findings based on the close interaction of the gene products within the Ras-mitogen-activated protein kinase pathway. Changes in other genes encoding mitogen-activated protein kinase pathway proteins are responsible for Noonan syndrome and the KRAS mutation phenotype.

SUMMARY

Costello syndrome is caused by heterozygous de-novo point mutations in HRAS, resulting in increased activation of the mitogen-activated protein kinase pathway. Despite their overlapping presentation, Costello syndrome and its related disorders are distinct, and the phenotypes become more distinctive with age. Molecular testing is available and a clinical diagnosis should be reconsidered if it is inconsistent with the molecular result.

What's new in the neuro-cardio-facial-cutaneous syndromes?

The RAS-MAPKinase pathway is a signal transduction cascade which has been studied extensively during the last decades for its role in human oncogenesis. Activation of this cascade is controlled by cycling of the RAS protein between an inactive and an active state and by phosphorylation of downstream proteins. The signalling cascade regulates cell proliferation, differentiation and survival. Disturbed RAS signalling in malignancies is caused by acquired somatic mutations in RAS genes or other components of this pathway. Recently, germline mutations in genes coding for different components of the RAS signalling cascade have been recognized as the cause of several phenotypically overlapping disorders, recently referred to as the neuro-cardio-facial-cutaneous syndromes. Neurofibromatosis type 1, Noonan, LEOPARD, Costello and cardiofaciocutaneous syndromes all present with variable degrees of psychomotor delay, congenital heart defects, facial dysmorphism, short stature, skin abnormalities and a predisposition for malignancy. These findings point to important roles for this evolutionary conserved pathway in oncogenesis, development, cognition and growth.

CONCLUSION

it has become obvious in recent years that the neuro-cardio-facial-cutaneous syndromes all share a common genetic and pathophysiologic basis. Dysregulation of the RAS-MAPKinase pathway is caused by germline mutations in genes involved in this pathway. Undoubtedly more genes causing related syndromes will be discovered in the near future since there are still a substantial number of genes in the pathway that are not yet associated with a known syndrome.

Further delineation of the phenotype resulting fromBRAForMEK1germline mutations helps differentiate cardio-facio-cutaneous syndrome from Costello syndrome

Because Cardio-facio-cutaneous (CFC) syndrome has significant phenotypic overlap with Costello syndrome, it may be difficult to establish the diagnosis on a clinical basis. The recent discoveries of germline HRAS mutations in patients with Costello syndrome and mutations in BRAF, MEK1, and MEK2 in CFC syndrome uncovered the biologic mechanism for the shared phenotypic findings based on the close interaction of the affected gene products within the MAP kinase pathway. We evaluated a series of patients who were either clinically diagnosed with Costello syndrome, or in whom the diagnoses of both Costello and CFC syndromes were considered. After excluding mutations in HRAS, we identified eight changes in BRAF and five in MEK1. Five mutations are novel, and all changes occurred de novo among those triads tested. A review of the clinical abnormalities showed important differences between patients with either a BRAF or MEK1 mutation, and those previously reported with an HRAS mutation. Statistical significance was achieved, despite the relatively small number of patients with BRAF and MEK1 mutations reported here, for polyhydramnios, growth hormone deficiency and the presence of more than one papilloma, which were less common in CFC compared to HRAS mutation positive patients. Although both CFC and Costello syndrome are characterized by cardiac abnormalities in about three-fourths of patients, the pattern of congenital heart defects (CHD), hypertrophic cardiomyopathy (HCM), and tachycardia differs somewhat. CHD, especially pulmonic stenosis associated with a secundum-type atrial septal defect, are more common in CFC than Costello syndrome (P = 0.02). Atrial tachycardia is less frequent in CFC patients with BRAF or MEK1 mutations, compared to Costello syndrome patients with HRAS mutation (P = 0.04). Chaotic atrial rhythm or multifocal atrial tachycardia was observed only in Costello syndrome. Malignant tumors have been viewed as characteristic for Costello syndrome due to HRAS mutations, however, we report here on a MEK1 mutation in a patient with a malignant tumor, a hepatoblastoma. Although this indicates that the presence of a tumor is not specific for Costello syndrome with HRAS mutation, it is noteworthy that the tumor histology differs from those commonly seen in Costello syndrome. Based on these clinical differences we suggest that patients with BRAF and MEK mutations should be diagnosed with CFC syndrome, and the diagnosis of Costello syndrome be reserved for patients with HRAS mutations.

Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

The intent of this review is to provide the clinician with a summary of what is currently known about the contribution of genetics to the origin of congenital heart disease. Techniques are discussed to evaluate children with heart disease for genetic alterations. Many of these techniques are now available on a clinical basis. Information on the genetic and clinical evaluation of children with cardiac disease is presented, and several tables have been constructed to aid the clinician in the assessment of children with different types of heart disease. Genetic algorithms for cardiac defects have been constructed and are available in an appendix. It is anticipated that this summary will update a wide range of medical personnel, including pediatric cardiologists and pediatricians, adult cardiologists, internists, obstetricians, nurses, and thoracic surgeons, about the genetic aspects of congenital heart disease and will encourage an interdisciplinary approach to the child and adult with congenital heart disease.

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.