Phenotypic Analysis of Individuals With Costello Syndrome due to HRAS p.G13C

Division of Medical Genetics, A. I. duPont Hospital for Children, Wilmington, Delaware, USA.
American Journal of Medical Genetics Part A (Impact Factor: 2.16). 04/2011; 155A(4):706-16. DOI: 10.1002/ajmg.a.33884
Source: PubMed


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.

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    • "It typically encompasses severe failure to thrive, cardiac abnormalities including tachyarrhythmia and hypertrophic cardiomyopathy, a predisposition to papillomata and malignant tumors, and neurologic abnormalities including Chiari 1 malformation and tethered cord, nystagmus, hypotonia and intellectual disability [Gripp and Lin, 2006, 2012]. Most patients have an HRAS mutation affecting the glycine residue in position 12 [Gripp et al., 2006; Kerr et al., 2006], and the glycine in position 13 is the second most commonly altered amino acid [Gripp et al., 2011a]. Specific amino acid substitutions, particularly those strongly inducing oncogenic cell transformation, may result in an early lethal phenotype [Lo et al., 2008]. "
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    ABSTRACT: Heterozygous germline mutations in the proto-oncogene HRAS cause Costello syndrome (CS), an intellectual disability condition with severe failure to thrive, cardiac abnormalities, predisposition to tumors, and neurologic abnormalities. More than 80% of patients share the HRAS mutation c.34G>A (p.Gly12Ser) associated with the typical, relatively homogeneous phenotype. Rarer mutations occurred in individuals with an attenuated phenotype and less characteristic facial features. Most pathogenic HRAS alterations affect hydrolytic HRAS activity resulting in constitutive activation. "Gain-of-function" and "hyperactivation" concerning downstream pathways are widely used to explain the molecular basis and dysregulation of the RAS-MAPK pathway is the biologic mechanism shared amongst rasopathies. Panel testing for rasopathies identified a novel HRAS mutation (c.179G>A; p.Gly60Asp) in three individuals with attenuated features of Costello syndrome. De novo paternal origin occurred in two, transmission from a heterozygous mother in the third. Individuals showed subtle facial features; curly hair and relative macrocephaly were seen in three; atrial tachycardia and learning difficulties in two, and pulmonic valve dysplasia and mildly thickened left ventricle in one. None had severe failure to thrive, intellectual disability or cancer, underscoring the need to consider HRAS mutations in individuals with an unspecific rasopathy phenotype. Functional studies revealed strongly increased HRAS(Gly60Asp) binding to RAF1, but not to other signaling effectors. Hyperactivation of the MAPK downstream signaling pathways was absent. Our results indicate that an increase in the proportion of activated RAS downstream signaling components does not entirely explain the molecular basis of CS. We conclude that the phenotypic variability in CS recapitulates variable qualities of molecular dysfunction. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.
    Full-text · Article · Apr 2015 · American Journal of Medical Genetics Part A
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    • "Rarer HRAS germline changes, including p.G12C, may be associated with a more severe phenotype [van der Burgt et al., 2007; Lo et al., 2008]; whereas others, such as p.G13C, may result in a milder phenotype [Gripp et al., 2008, 2011]. Because the growth parameters of individuals with HRAS p.G13C may be closer to the range for typical individuals than those of patients with p.G12S [Gripp et al., 2011], it is important to note that data from Costello syndrome patients with rare mutations are included in our analysis (Table I). Limitations of our study are largely due to the small number of patients with Costello syndrome, and are compounded by the lack of reliable growth data as exemplified by our inability to generate OFC centiles past age 36 months. "
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    ABSTRACT: Costello syndrome is a rare condition due to heterozygous germline mutations in the proto-oncogene HRAS. It affects multiple organ systems and includes severe failure-to-thrive, short stature, and macrocephaly. The goal of this study was to develop Costello syndrome-specific growth curves. We collected height, weight, and head circumference (OFC) measurements from 94 individuals (45 males and 49 females). Their HRAS mutation spectrum reflects previously published cohorts, with p.G12S in 77.7%. Participants received medical care, therefore our data does not reflect natural history per se, but rather growth with nutritional support. Due to limited cohort size, we analyzed data from males and females together. Weight-for-age data included 417 separate measurements from 80 individuals age 0-36 months, and 585 measurements from 82 individuals for age 0-10 years. Height-for-age data were derived from 391 measurements from 77 individuals age 0-36 months, and 591 measurements from 90 individuals age 0-10 years. Measurements obtained after growth hormone exposure in 15 individuals were excluded in this analysis. The OFC curve was derived from 221 measurements from 55 individuals age 0-36 months. Centiles (5th, 50th, and 95th) were estimated across the age continuum for each growth parameter, and compared to gender-specific curves for average stature individuals. The resulting curves demonstrate very slow weight gain in the first 2 years. Short stature is seen in many, but after age 4 years the 95th centile for height falls within the low normal range for average stature children. Head circumference curves largely overlap those for average stature, reflecting relative macrocephaly. © 2012 Wiley Periodicals, Inc.
    Full-text · Article · Nov 2012 · American Journal of Medical Genetics Part A
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    • "Common clinical features include prenatal overgrowth and polyhydramnios, severe postnatal failure to thrive, short stature, developmental delay, congenital heart disease, and cardiomyopathy [Kerr, 2009]. Whilst CS often has a relatively homogenous phenotype, both milder and more severe phenotypes are now recognized, which often arise due to less common mutations [Kerr et al., 2006; van der Burgt et al., 2007; Gripp et al., 2011]. "
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    ABSTRACT: De novo heterozygous mutations in HRAS cause Costello syndrome (CS), a condition with high mortality and morbidity in infancy and early childhood due to cardiac, respiratory, and muscular complications. HRAS mutations predicting p.Gly12Val, p.Gly12Asp, and p.Gly12Cys substitutions have been associated with severe, lethal, CS. We report on molecular, clinical, and pathological findings in patients with mutations predicting HRAS p.Gly12Val that were identified in our clinical molecular genetic testing service. Such mutations were identified in four patients. Remarkably, three were deletion/insertion mutations affecting coding nucleotides 35 and 36. All patients died within 6 postnatal weeks, providing further evidence that p.Gly12Val mutations predict a very poor prognosis. High birth weight, polyhydramnios (and premature birth), cardiac hypertrophy, respiratory distress, muscle weakness, and postnatal growth failure were present. Dysmorphism was subtle or non-specific, with edema, coarsened facial features, prominent forehead, depressed nasal bridge, anteverted nares, and low-set ears. Proximal upper limb shortening, a small bell-shaped chest, talipes, and fixed flexion deformities of the wrists were seen. Neonatal atrial arrhythmia, highly suggestive of CS, was also present in two patients. One patient had congenital alveolar dysplasia, and another, born after 36 weeks' gestation, bronchopulmonary dysplasia. A rapidly fatal disease course, and the difficulty of identifying subtle dysmorphism in neonates requiring intensive care, suggest that this condition remains under-recognized, and should enter the differential diagnosis for very sick infants with a range of clinical problems including cardiac hypertrophy and disordered pulmonary development. Clinical management should be informed by knowledge of the poor prognosis of this condition.
    Full-text · Article · May 2012 · American Journal of Medical Genetics Part A
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