Phenotypic Analysis of Individuals With Costello Syndrome due to HRAS p.G13C
ABSTRACT 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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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.American Journal of Medical Genetics Part A 11/2012; 158A(11):2692-9. DOI:10.1002/ajmg.a.35534 · 2.05 Impact Factor
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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.American Journal of Medical Genetics Part A 05/2012; 158A(5):1102-10. DOI:10.1002/ajmg.a.35296 · 2.05 Impact Factor
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ABSTRACT: Costello syndrome is a rare rasopathy resulting from germline mutations of the proto-oncogene HRAS. Its phenotype includes severe failure-to-thrive, cardiac abnormalities, a predisposition to benign and malignant tumors, hypotonia, and developmental delay. Costello syndrome is associated with cognitive impairment, including intellectual functioning generally in the mild to moderate range of disability, commensurate adaptive functioning, and increased anxiety. Relative strengths have been found for nonverbal fluid reasoning (FR). Gender effects have been reported, with females showing better adaptive functioning across domains. Developmentally, nonverbal skills plateau in late childhood/early adolescence, whereas the rate of vocabulary acquisition may increase in adolescence into early adulthood. Here we review the literature assessing cognitive, adaptive, and behavioral functioning in Costello syndrome, and we provide data from an ongoing longitudinal study. Severity of cognitive impairment may depend upon the specific HRAS mutation, as three individuals with the p.G13C change showed average nonverbal FR skills and borderline-to-low average overall nonverbal IQ. Further, separation anxiety is more common in Costello syndrome than in the general population, affecting 39% of this cohort, and males are more often overly anxious than females. Interrelations between anxiety and cognitive and adaptive functioning were found, pointing to functional difficulties as a likely source of stress and anxiety. Taking into account data from animal models, cognitive and behavioral changes likely originate from abnormal differentiation of neuronal precursor cells, which result in structural and functional brain differences.American Journal of Medical Genetics Part C Seminars in Medical Genetics 05/2011; 157(2):115-22. DOI:10.1002/ajmg.c.30299 · 3.54 Impact Factor