Costello syndrome and related disorders

RASopathies - what they reveal about RAS/MAPK signaling in skeletal muscle development

RASopathies are rare developmental genetic syndromes caused by germline pathogenic variants in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) signal transduction pathway. Although the incidence of each RASopathy syndrome is rare, collectively, they represent one of the largest groups of multiple congenital anomaly syndromes and have severe developmental consequences. Here, we review our understanding of how RAS/MAPK dysregulation in RASopathies impacts skeletal muscle development and the importance of RAS/MAPK pathway regulation for embryonic myogenesis. We also discuss the complex interactions of this pathway with other intracellular signaling pathways in the regulation of skeletal muscle development and growth, and the opportunities that RASopathy animal models provide for exploring the use of pathway inhibitors, typically used for cancer treatment, to correct the unique skeletal myopathy caused by the dysregulation of this pathway.

Precision Medicine in Congenital Heart Disease, Rheumatic Heart Disease, and Kawasaki Disease of Children: An Overview of Literature

Congenital heart disease and common acquired heart diseases like Kawasaki disease and rheumatic heart disease are prevalent cardiovascular conditions in children worldwide. Despite the availability of treatment options, they continue to be significant contributors to morbidity and mortality. Advancements in early diagnosis, improvements in treatment approaches, and overcoming resistance to available treatments are crucial to reduce morbidity. Researchers have turned to precision medicine to tackle these challenges. We aimed to analyze the existing literature concerning the utilization of precision medicine in congenital heart disease, rheumatic heart disease, and Kawasaki disease. The emphasis is placed on comprehending the key themes explored in these studies and evaluating the present state of their clinical integration. The central theme of most studies revolves around the examination of genetic factors. Despite promising research outcomes, limitations in these studies indicate that the clinical implementation of precision medicine in these conditions remains a distant prospect, necessitating additional exploration and attention to confounding factors.

Vascular malformation rupture in a patient affected by Costello syndrome

Costello syndrome (CS) is a rare genetic syndrome affecting multiple organs, generally caused by mutations of the HRAS gene, belonging to the RAS/MAPK genes family.A male patient with CS developed a painful pulsatile mass on the lateral side of the wrist. An initial ultrasonographic investigation confirmed the presence of a radial artery lesion, possibly an arterial aneurysm. On surgical resection, histological evaluation showed a tangle of vascular structures with variable calibre and abnormal wall histology. Immunohistochemical stainings revealed a very poor endothelial contribution to the central vascular wall structure. These histological observations led us to conclude we had managed an acute vascular malformation (VM) rupture, rather than a common arterial aneurysmal condition. Considering the molecular mechanisms regulated by RAS/MAPK genes, CS patients might have a higher risk of developing VMs and, in the presence of a pulsatile mass with acute onset, VM rupture should be considered.

MEK-inhibitor-mediated rescue of skeletal myopathy caused by activating Hras mutation in a Costello syndrome mouse model

Costello syndrome (CS) is a congenital disorder caused by heterozygous activating germline HRAS mutations in the canonical Ras/mitogen-activated protein kinase (Ras/MAPK) pathway. CS is one of the RASopathies, a large group of syndromes caused by mutations within various components of the Ras/MAPK pathway. An important part of the phenotype that greatly impacts quality of life is hypotonia. To gain a better understanding of the mechanisms underlying hypotonia in CS, a mouse model with an activating Hras^G12V allele was utilized. We identified a skeletal myopathy that was due, in part, to inhibition of embryonic myogenesis and myofiber formation, resulting in a reduction in myofiber size and number that led to reduced muscle mass and strength. In addition to hyperactivation of the Ras/MAPK and PI3K/AKT pathways, there was a significant reduction in p38 signaling, as well as global transcriptional alterations consistent with the myopathic phenotype. Inhibition of Ras/MAPK pathway signaling using a MEK inhibitor rescued the Hras^G12V myopathy phenotype both in vitro and in vivo, demonstrating that increased MAPK signaling is the main cause of the muscle phenotype in CS.

Summary: A Costello syndrome (CS) mouse model carrying a heterozygous Hras p.G12V mutation was utilized to investigate Ras pathway dysregulation, revealing that increased MAPK signaling is the main cause of the muscle phenotype in CS.

Next-generation gene panel testing in adolescents and adults in a medical neuropsychiatric genetics clinic

Intellectual disability (ID) encompasses a clinically and genetically heterogeneous group of neurodevelopmental disorders that may present with psychiatric illness in up to 40% of cases. Despite the evidence for clinical utility of genetic panels in pediatrics, there are no published studies in adolescents/adults with ID or autism spectrum disorder (ASD). This study was approved by our institutional research ethics board. We retrospectively reviewed the medical charts of all patients evaluated between January 2017 and December 2019 in our adult neuropsychiatric genetics clinic at the McGill University Health Centre (MUHC), who had undergone a comprehensive ID/ASD gene panel. Thirty-four patients aged > 16 years, affected by ID/ASD and/or other neuropsychiatric/behavioral disorders, were identified. Pathogenic or likely pathogenic variants were identified in one-third of our cohort (32%): 8 single-nucleotide variants in 8 genes (CASK, SHANK3, IQSEC2, CHD2, ZBTB20, TREX1, SON, and TUBB2A) and 3 copy number variants (17p13.3, 16p13.12p13.11, and 9p24.3p24.1). The presence of psychiatric/behavioral disorders, regardless of the co-occurrence of ID, and, at a borderline level, the presence of ID alone were associated with positive genetic findings (p = 0.024 and p = 0.054, respectively). Moreover, seizures were associated with positive genetic results (p = 0.024). One-third of individuals presenting with psychiatric illness who met our red flags for Mendelian diseases have pathogenic or likely pathogenic variants which can be identified using a comprehensive ID/ASD gene panel (~ 2500 genes) performed on an exome backbone.

Expanding the clinical phenotype of RASopathies in 38 Turkish patients, including the rare LZTR1, RAF1, RIT1 variants, and large deletion in NF1

RASopathies are a group of disorders caused by pathogenic variants in the genes encoding Ras/mitogen-activated protein kinase pathway and share overlapping clinical and molecular features. This study is aimed to describe the clinical and molecular features of 38 patients with RASopathies. Sanger or targeted next-generation sequencing of related genes and multiplex ligation-dependent-probe amplification analysis for NF1 were performed. The pathogenic variant detection rate was 94.4%. While PTPN11 was responsible for 50% of 18 patients with Noonan syndrome (NS), SOS1, LZTR1, RIT1, and RAF1 were responsible for the remaining 27.8%, 11.1%, 5.5%, and 5.5%, respectively. Three variants in LZTR1 were novel, of which two were identified in the compound heterozygous state in a patient with intellectual disability and hypertrophic cardiomyopathy, whereas the third variant was found in the heterozygous state in a patient with pulmonary stenosis and normal intelligence. We described pyloric stenosis, knee dislocation, and cleft palate in patients with SOS1, RIT1, and RAF1 variants, respectively, that was not previously reported. We detected a PTPN11 variant in three patients from same family with NS with multiple lentigines. BRAF and MAP2K2 variants were found in eight patients with Cardiofaciocutaneous syndrome. Two variants in HRAS were detected in two Costello syndrome patients, one with a mild and the other with a severe phenotype. While large NF1 deletions were identified in four Neurofibromatosis-NS patients with intellectual disability, intelligence was normal in one patient with missense variant. In conclusion, this study provided three novel variants in LZTR1 and expanded the clinical phenotype of rare RASopathies.

Two rare presentations of embryonal rhabdomyosarcoma of the cervix in teenagers at a low-resource teaching hospital in Ghana: A case series

•

We report on two cases of embryonal rhabdomyosarcoma of the cervix in Ghana.

•

Only 20% of rhabdomyosarcoma diagnoses in children occur in the genitourinary tract.

•

Embryonal rhabdomyosarcoma of the cervix is rare, with no standardized treatment.

•

The teenaged patients underwent fertility-sparing surgery followed by chemotherapy.

•

This treatment regimen is accessible in low-income countries.

We report two cases of embryonal rhabdomyosarcoma (ERMS) of the cervix in teenagers presenting to Komfo Anokye Teaching Hospital in Kumasi, Ghana within one month of each other. Between October and November 2019, two patients presented with ERMS of the cervix. They both underwent fertility-sparing surgery followed by chemotherapy with vincristine, actinomycin-D, and cyclophosphamide. Preoperative workup for the two patients was minimal due to limited availability and high cost of imaging in a low-resource setting. Both patients were discussed at a multidisciplinary tumor board meeting to guide best management practices. Both patients had local surgical resection with histological confirmation of ERMS and negative margins, followed by six cycles of vincristine, actinomycin-D, and cyclophosphamide. Neither of the patients had perioperative complications or received radiation therapy. At the time of publication, both patients are currently alive and without evidence of recurrence. Fertility-sparing surgery followed by chemotherapy for patients with ERMS of the cervix is accessible in low-income countries.

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.

Costello syndrome: Clinical phenotype, genotype, and management guidelines

Costello syndrome (CS) is a RASopathy caused by activating germline mutations in HRAS. Due to ubiquitous HRAS gene expression, CS affects multiple organ systems and individuals are predisposed to cancer. Individuals with CS may have distinctive craniofacial features, cardiac anomalies, growth and developmental delays, as well as dermatological, orthopedic, ocular, and neurological issues; however, considerable overlap with other RASopathies exists. Medical evaluation requires an understanding of the multifaceted phenotype. Subspecialists may have limited experience in caring for these individuals because of the rarity of CS. Furthermore, the phenotypic presentation may vary with the underlying genotype. These guidelines were developed by an interdisciplinary team of experts in order to encourage timely health care practices and provide medical management guidelines for the primary and specialty care provider, as well as for the families and affected individuals across their lifespan. These guidelines are based on expert opinion and do not represent evidence-based guidelines due to the lack of data for this rare condition.

Oligodendrocyte RasG12V expressed in its endogenous locus disrupts myelin structure through increased MAPK, nitric oxide, and notch signaling

Costello syndrome (CS) is a gain of function Rasopathy caused by heterozygous activating mutations in the HRAS gene. Patients show brain dysfunction that can include abnormal brain white matter. Transgenic activation of HRas in the entire mouse oligodendrocyte lineage resulted in myelin defects and behavioral abnormalities, suggesting roles for disrupted myelin in CS brain dysfunction. Here, we studied a mouse model in which the endogenous HRas gene is conditionally replaced by mutant HRasG12V in mature oligodendrocytes, to separate effects in mature myelinating cells from developmental events. Increased myelin thickness due to decompaction was detectable within one month of HRasG12V expression in the corpus callosum of adult mice. Increases in active ERK and Nitric Oxide (NO) were present in HRas mutants and inhibition of NO synthase (NOS) or MEK each partially rescued myelin decompaction. In addition, genetic or pharmacologic inhibition of Notch signaling improved myelin compaction. Complete rescue of myelin structure required dual drug treatments combining MAPK, NO, or Notch inhibition; with MEK + NOS blockade producing the most robust effect. We suggest that individual or concomitant blockade of these pathways in CS patients may improve aspects of brain function.

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.

The Role of Childhood Infections and Immunizations on Childhood Rhabdomyosarcoma: A Report From the Children's Oncology Group

BACKGROUND

Rhabdomyosarcoma (RMS) is a rare, highly malignant tumor arising from primitive mesenchymal cells that differentiate into skeletal muscle. Relatively little is known about RMS susceptibility. Based on growing evidence regarding the role of early immunologic challenges on RMS development, we evaluated the role of infections and immunizations on this clinically significant pediatric malignancy.

PROCEDURE

RMS cases (n = 322) were enrolled from the third trial coordinated by the Intergroup Rhabdomyosarcoma Study Group. Population-based controls (n = 322) were pair matched to cases on race, sex, and age. The following immunizations were assessed: diphtheria, pertussis, and tetanus (DPT); measles, mumps, and rubella; and oral polio vaccine. We also evaluated if immunizations were complete versus incomplete. We examined selected infections including chickenpox, mumps, pneumonia, scarlet fever, rubella, rubeola, pertussis, mononucleosis, and lung infections. Conditional logistic regression models were used to calculate an odds ratio (OR) and 95% confidence interval (CI) for each exposure, adjusted for maternal education and total annual income.

RESULTS

Incomplete immunization schedules (OR = 5.30, 95% CI: 2.47-11.33) and incomplete DPT immunization (OR = 1.56, 95% CI: 1.06-2.29) were positively associated with childhood RMS. However, infections did not appear to be associated with childhood RMS.

CONCLUSIONS

This is the largest study of RMS to date demonstrating a possible protective effect of immunizations against the development of childhood RMS. Further studies are needed to validate our findings. Our findings add to the growing body of literature, suggesting a protective role of routine vaccinations in childhood cancer and specifically in childhood RMS.

Behavioral functioning in cardiofaciocutaneous syndrome: Risk factors and impact on parenting experience

The present study is an investigation of behavioral functioning in children with cardiofaciocutaneous syndrome (CFC). CFC is a rare single-gene disorder associated with cardiac disease, characteristic skin and facial features, intellectual disability, and neurological complications such as seizures and structural brain anomalies. Emotional and behavioral features of CFC have not been systematically investigated. We aimed to identify key variables that contribute to psychopathology during childhood and adolescence, and to examine the impact of challenging behaviors on the caregiving experience. Parents of 34 children and adolescents with CFC completed standardized broadband measures of child emotional and behavioral functioning, as well as measures of sensory modulation, functional communication, and caregiver stress. Results indicate that children with CFC syndrome are at heightened risk for psychopathology, with attention problems, social difficulties, and unusual behaviors (e.g., obsessive thoughts, strange behaviors, repetitive acts) found to be especially prevalent. Behavioral challenges in children with CFC syndrome were significantly associated with a history of obstetric complications and with problems modulating sensory information. With regard to the impact of child neurocognitive and behavioral issues on the caregiving experience, parent self-reported stress was significantly higher among parents of children who engaged in more problem behaviors, and lower among parents whose children could communicate effectively with others. Results of this study suggest avenues to help families cope with CFC-related stressors and enhance overall functioning. In particular, this study highlights the need for educational and treatment interventions aimed at addressing sensory needs, increasing functional communication, and identifying and managing challenging behaviors. © 2016 Wiley Periodicals, Inc.

The prognostic value of family history among patients with urinary bladder cancer

A history of urinary bladder cancer (UBC) in first-degree relatives increases UBC risk by twofold. The influence of positive family history on UBC prognosis is unknown. Here, we investigated association of first-degree UBC family history with clinicopathological characteristics and prognosis of UBC patients. Detailed clinical data of 1,465 non-muscle-invasive bladder cancer (NMIBC) and 250 muscle-invasive or metastatic bladder cancer (MIBC) patients, diagnosed from 1995 to 2010, were collected through medical file review. Competing risk analyses were used to compare recurrence-free survival (RFS) and progression-free survival (PFS) of NMIBC patients according to self-reported UBC family history. Overall survival in MIBC patients was estimated using Kaplan-Meier analysis. The added value of family history in prediction of NMIBC prognosis was quantified with Harrell's concordance-index. Hundred (6.8%) NMIBC and 14 (5.6%) MIBC patients reported UBC in first-degree relatives. Positive family history was statistically significantly associated with smaller tumor size and non-significantly with more favorable distribution of other tumor characteristics. In univariable analyses, positive family history correlated with longer RFS (p = 0.11) and PFS (p = 0.04). Hazard ratios for positive vs. negative family history after adjustment for clinicopathological characteristics were 0.75 (95% CI = 0.53–1.07) and 0.45 (95% CI = 0.18–1.12) for RFS and PFS, respectively. Five familial and 48 sporadic MIBC patients (Kaplan-Meier 10-year risk: 41% and 25%) died within 10 years. Family history did not improve the c-index of prediction models. This study shows that a first-degree family history of UBC is not clearly associated with NMIBC prognosis. Family history does not aid in prediction of NMIBC recurrence or progression.

Second-trimester prenasal and prefrontal skin thickening - association with MECP2 triplication syndrome

MECP2 triplication syndrome is a rare and usually lethal genetic disorder characterized by progressive neurologic and cognitive regression. None of the four reported cases describe prenatal sonographic features of affected offspring. We report a second-trimester fetus with marked prefrontal and prenasal skin thickening, retrognathia, and later, third-trimester mild cerebral ventriculomegaly. Amniocyte karyotype was normal male, but newborn whole-genome oligonucleotide microarray showed duplication and triplication of chromosome Xq28 containing the MECP2 gene. Comparative genomic hybridization may be diagnostic in fetuses with prefrontal and prenasal skin thickening, additional sonographic findings, and normal karyotype.

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.

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.

Germline genetic markers for urinary bladder cancer risk, prognosis and treatment response

After decades of research using a candidate gene approach, only NAT2 and GSTM1 have consistently been demonstrated to be germline genetic susceptibility markers for urinary bladder cancer (UBC). The recent shift to an agnostic genome-wide association approach led to the identification of several UBC susceptibility loci, and provided valuable leads for new mechanistic insights into UBC carcinogenesis. The markers do not have sufficient discriminatory ability yet to be applied for risk assessment in the population and the question is whether they ever will. Prognostic and predictive studies in UBC are still in their infancy compared with etiologic studies. In the future, focus on a genome-wide association approach possibly using whole-genome sequence data, consortia formation and meta-analyses, and blood and tumor tissue collection, preferably in the context of randomized controlled trials will stimulate well designed and sufficiently powered studies, and thereby enhance the elucidation of genetic prognostic and predictive markers.

Metastatic alveolar rhabdomyosarcoma in multiple endocrine neoplasia type 2A

Rhabdomyosarcoma (RMS), the most common pediatric soft tissue sarcoma, accounts for 3% of childhood malignancies. Multiple Endocrine Neoplasia (MEN) type 2A is an autosomal dominant syndrome associated with near universal development of medullary thyroid carcinoma. We describe a previously unreported association of MEN-2A with metastatic alveolar RMS and review the literature on associated hereditary cancer predisposition syndromes and current therapeutic options. The high penetrance of malignancy in patients with MEN warrants a heightened suspicion for the development of nonendocrine malignancies. The diagnosis of RMS should prompt consideration of screening for familial genetic syndromes in certain patients.

The diagnostic and clinical significance of café-au-lait macules

Café-au-lait, also referred to as café-au-lait spots or café-au-lait macules, present as well-circumscribed, evenly pigmented macules and patches that range in size from 1 to 2 mm to greater than 20 cm in greatest diameter. Café-au-lait are common in children. Although most café-au-lait present as 1 or 2 spots in an otherwise healthy child, the presence of multiple café-au-lait, large segmental café-au-lait, associated facial dysmorphism, other cutaneous anomalies, or unusual findings on physical examination should suggest the possibility of an associated syndrome. While neurofibromatosis type 1 is the most common syndrome seen in children with multiple café-au-lait, other syndromes associated with one or more café-au-lait include McCune-Albright syndrome, Legius syndrome, Noonan syndrome and other neuro-cardio-facialcutaneous syndromes, ring chromosome syndromes, and constitutional mismatch repair deficiency syndrome.

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.

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.

Inherited cancer syndromes in children and young adults

Geneticists estimate that 5% to 10% of all cancers diagnosed in the pediatric age range occur in children born with a genetic mutation that directly increases their lifetime risk for neoplasia. However, despite the fact that only a fraction of cancers in children occur as a result of an identified inherited predisposition, characterizing genetic mutations responsible for increased cancer risk in such syndromes has resulted in a profound understanding of relevant molecular pathways involved in carcinogenesis and/or resistance to neoplasia. Importantly, because most cancer predisposition syndromes result in an increased risk of a small number of defined malignancies, personalized prophylactic surveillance and preventive measures can be implemented in affected patients. Lastly, many of the same genetic targets identified from cancer-prone families are mechanistically involved in the majority of sporadic cancers in adults and children, thereby underscoring the clinical relevance of knowledge gained from these defined syndromes and introducing novel therapeutic opportunities to the broader oncologic community. This review highlights the clinical and genetic features of many of the known constitutional genetic syndromes that predispose to malignancy in children and young adults.

Genome-wide association studies in bladder cancer: first results and potential relevance

PURPOSE OF REVIEW

The role of genetic susceptibility in the development of urinary bladder cancer is unclear, as it is in many other types of cancer. Since 2007, however, an innovative research approach (i.e. genome-wide association studies or GWASs) has led to the identification of numerous genomic loci that harbor susceptibility factors for one or more cancer sites. All GWASs have been published in high-impact journals and the strengths of the design are acknowledged by all experts, but there is criticism about the relevance of the results. Late 2008, the first GWAS in bladder cancer was published.

RECENT FINDINGS

In this review, the principles of GWASs are explained, as well as their strengths and limitations. The study in bladder cancer among 4000 cases and 38,000 controls identified three new susceptibility loci at 8q24, 3q28, and 5p15 that increase the risk of bladder cancer by 22, 19, and 16%, respectively. The results of two other GWASs in bladder cancer are expected to appear this year. Joint analysis of the three studies will probably identify additional susceptibility loci.

SUMMARY

The results of bladder cancer GWASs may point the way to yet unknown disease mechanisms. So far, the findings are not sufficiently discriminative for risk predictions to be used in clinical care or public health.

Cardiomyocyte-specific loss of neurofibromin promotes cardiac hypertrophy and dysfunction

RATIONALE

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder with a broad array of clinical manifestations, including benign and malignant tumors, and characteristic cutaneous findings. NF1 patients also have an increased incidence of cardiovascular diseases, including obstructive vascular disorders and hypertension. The disease gene, NF1, encodes neurofibromin, a ubiquitously expressed protein that acts, in part, as a Ras-GAP (GTP-ase activating protein), downregulating the activity of activated Ras protooncogenes. In animal models, endothelial and smooth muscle expression of the disease gene is critical for normal heart development and the prevention of vascular disease, respectively.

OBJECTIVE

To determine the role of NF1 in the postnatal and adult heart.

METHODS AND RESULTS

We generated mice with homozygous loss of the murine homolog Nf1 in myocardium (Nf1mKO) and evaluated their hearts for biochemical, structural, and functional changes. Nf1mKO mice have normal embryonic cardiovascular development but have marked cardiac hypertrophy, progressive cardiomyopathy, and fibrosis in the adult. Hyperactivation of Ras and downstream pathways are seen in the heart with the loss of Nf1, along with activation of a fetal gene program.

CONCLUSIONS

This report describes a critical role of Nf1 in the regulation of cardiac growth and function. Activation of pathways known to be involved in cardiac hypertrophy and dysfunction are seen with the loss of myocardial neurofibromin.

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.