Spectrum of SMARCB1/INI1 mutations in familial and sporadic rhabdoid tumors

Background

Germline mutations and deletions of SMARCB1/INI1 in chromosome band 22q11.2 predispose patients to rhabdoid tumor and schwannomatosis. Previous estimates suggested that 15–20% of rhabdoid tumors were caused by an underlying germline abnormality of SMARCB1. However, these studies were limited by case selection and an inability to detect intragenic deletions and duplications.

Procedure

One hundred matched tumor and blood samples from patients with rhabdoid tumors of the brain, kidney, or soft tissues were analyzed for mutations and deletions of SMARCB1 by FISH, multiplex ligation‐dependent probe amplification (MLPA), sequence analysis and high resolution Illumina 610K SNP‐based oligonucleotide array studies.

Results

Thirty‐five of 100 patients were found to have a germline SMARCB1 abnormality. These abnormalities included point and frameshift mutations, intragenic deletions and duplications, and larger deletions including regions both proximal and distal to SMARCB1. There were nine cases that demonstrated parent to child transmission of a mutated copy of SMARCB1. In eight of the nine cases, one or more family members were also diagnosed with rhabdoid tumor or schwannoma, and two of the eight families presented with multiple affected children in a manner consistent with gonadal mosaicism.

Conclusions

Approximately one‐third of newly diagnosed patients with rhabdoid tumor have an underlying genetic predisposition to tumors due to a germline SMARCB1 alteration. Families may demonstrate incomplete penetrance and gonadal mosaicism, which must be considered when counseling families of patients with rhabdoid tumor. Pediatr Blood Cancer. 2010;56:7–15. © 2010 Wiley‐Liss, Inc.     

Absence of BRAF mutation in pediatric and adolescent germ cell tumors indicate biological differences to adult tumors

The V600E mutation of the BRAF gene has been reported to be associated with poor prognosis of germ cell tumors in adult patients. We analyzed the mutational status of the BRAF and KRAS gene as well as MLH1 and MSH6 expression as surrogate markers for microsatellite instability in 70 pediatric germ cell tumors. Neither BRAF and KRAS mutations nor loss of MLH1 and MSH6 expression were found. Our data provide further evidence for patient age related biological differences in germ cell tumors and demonstrate that prognostic biomarkers cannot necessarily be transferred from one age group to the other.     

Absence of serum chemistry abnormalities in pediatric patients presenting with seizures.

To determine the utility of the routine practice of obtaining serum chemistry values on children presenting after a seizure, we reviewed the emergency department records of 241 episodes of seizures in pediatric patients. One hundred fifty-five nonfebrile (49 initial, 106 recurrent) and 86 febrile (53 initial, 33 recurrent) convulsive episodes were analyzed. At least one serum chemistry value was obtained in 149 (64%) patients. Clinically significant abnormalities were found in 0/149 serum sodium, 0/148 glucose and blood urea nitrogen, 0/86 calcium, and 0/61 magnesium studies. We concluded that routine determination of serum chemistry values in pediatric patients presenting with a seizure is unnecessary unless specific clinical data strongly suggest otherwise.     

Rare variant mutations identified in pediatric patients with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) in infants and children can be partially explained by genetic cause but the catalogue of known genes is limited. We reviewed our database of 41 cases diagnosed with DCM before 18 years of age who underwent detailed clinical and genetic evaluation, and summarize here the evidence for mutations causing DCM in these cases from 15 genes (PSEN1, PSEN2, CSRP3, LBD3, MYH7, SCN5A, TCAP, TNNT2, LMNA, MYBPC3, MYH6, TNNC1, TNNI3, TPM1, and RBM20). Thirty-five of the 41 pediatric cases had relatives with adult-onset DCM. More males (66%) were found among children diagnosed after 1 year of age with DCM. Nineteen mutations in 9 genes were identified among 15 out of 41 patients; 3 patients (diagnosed at ages 2 weeks, 9 and 13 years) had multiple mutations. Of the 19 mutations identified in 12 families, mutations in TPM1 (32%) and TNNT2 (21%) were the most commonly found. Of the 6 patients diagnosed before 1 year of age, 3 had mutations in TPM1 (including a set of identical twins), 1 in TNNT2, 1 in MYH7, and 1 with multiple mutations (MYH7 and TNNC1). Most DCM was accompanied by advanced heart failure and need for cardiac transplantation. We conclude that in some cases pediatric DCM has a genetic basis, which is complicated by allelic and locus heterogeneity as seen in adult-onset DCM. We suggest that future prospective comprehensive family-based genetic studies of pediatric DCM are indicated to further define mutation frequencies in known genes and to discover novel genetic cause.     

Risk of venous thromboembolism in pediatric patients with brain tumors

BACKGROUND: Venous thromboembolism (VTE) is a common event in adults with malignant brain tumors approaching 24% throughout the course of the disease. The high morbidity and mortality of this complication yielded several protocols for prevention of the disease in adults undergoing neurosurgery for brain tumors and possible primary prevention afterwards. We investigated the incidence and complications of VTE in pediatric neuro-oncology patients. PROCEDURE: We analyzed, retrospectively, the files of all consecutive patients under the age of 18 years who were hospitalized for the treatment of brain tumors between the years 1990 and 2003 in two leading, closely related, Israeli neuro-oncology centers. RESULTS: A total of 462 children were analyzed. Three hundred eighty-four patients underwent surgery and 78 were treated medically. Only three (0.64%) of the patients developed clinical episodes of VTE that were treated conservatively. Two of these patients developed intracranial bleeding while on secondary prevention for the disease. CONCLUSIONS: Although this study has considerable limitations in terms of retrospective design, heterogeneous group of patients and diagnoses, the changing awareness for thrombosis over the last 14 years and the inclusion of symptomatic VTE events only, our surprising data suggest that, as opposed to adults, the risk of clinically significant VTE in children with brain tumors may be exceedingly low. These findings set the stage for future forthcoming evaluations in view of the prospective studies that were done in adults and the possible significant implications for the prevention and possible etiologies of the disease.     

Premature thelarche and granulosa cell tumors: a search for FSH receptor and G5alpha activating mutations

Activating mutations of the Gsalpha gene are responsible for McCune-Albright syndrome and have also been identified in sporadic tumors of the pituitary and thyroid. When associated with malignancy, activating Gsalpha mutations are known as gsp-oncogenes. We hypothesized that similar activating mutations might also account for some cases of premature thelarche and/ or granulosa cell tumors. Polymerase chain reaction and DNA sequencing was used to screen for activating mutations of Gsalpha genes in children with premature thelarche and in pathologic specimens from juvenile and adult granulosa cell tumors. Because these disorders involve over-activity of the FSH-signaling pathway, we also screened for activating mutations of the FSH receptor. No mutations were detected in either the Gsalpha or the FSHR fragment studied. Previously reported polymorphisms (Ser680Asn and Ala307Thr) of the FSHR were detected in 25/27 tumor samples and 9/9 premature thelarche samples. We conclude that activating mutations in previously identified mutation 'hot-spots' in the Gsalpha and FSH receptor genes are probably not a major cause of premature thelarche or granulosa cell tumors. In contrast, polymorphisms of the FSH receptor are common.     

Thyroid hemiagenesis is a rare variant of thyroid dysgenesis with a familial component but without Pax8 mutations in a cohort of 22 cases

Thyroid hemiagenesis is a rare form of thyroid dysgenesis of which some familial cases have been reported, including one associated with a heterozygous mutation in the Pax8 gene. However, the physiopathology remains not well known. The objectives of this study were 1) to describe the clinical features, 2) to look for familial clustering, and 3) to search for Pax8 mutations in a relatively large cohort of affected patients. A family history of thyroid dysgenesis was found in nine patients (40%), whose affected relatives had ectopic thyroid (n = 4), athyreosis (n = 1), thyroid hemiagenesis (n = 2), or thyroglossal duct cysts (n = 2). Screening for Pax8 mutations identified abnormal migration profiles by SSCP analysis in 3 patients, but direct sequencing did not show coding region mutations in any of the 22 patients. In conclusion, this study provides the first evidence that thyroid hemiagenesis can occur as a familial disorder associated with any form of thyroid dysgenesis. This finding supports both a common underlying mechanism to the various abnormalities in thyroid development and a role for genetic factors; however, our results from Pax8 analysis suggest that this gene may not be a key factor.     

Turner's syndrome and thyroid disease: a transverse study of pediatric patients in Brazil

An increased prevalence of autoimmune thyroid disease (AITD) has been described in Turner's syndrome (TS), but the extent of this association is still controversial. Some studies also suggest that AITD is more frequent among patients with X-isochromosome. In order to determine the prevalence of AITD among girls with TS, and to look for an association with age and karyotype, we evaluated 71 patients with a mean age of 11.4 years (range 0-19.9). 15.5% (11/71) were hypothyroid, 17 (23.9%) were positive for thyroid peroxidase (TPO) and/or thyroglobulin (Tg) antibodies, and 24 (33.8%) had thyromegaly. No abnormality was observed before 4 years, and the highest frequencies were observed after 16 years. There were no significant differences concerning thyroid findings among patients with a 45,X karyotype, mosaics, and structural rearrangements. Half of the patients (35/71) exhibited one or more abnormalities, which demonstrates the importance of careful evaluation of thyroid function in all girls with TS.     

婴幼儿原发性心脏肿瘤的诊断与治疗

目的:总结婴幼儿原发性心脏肿瘤的诊断和治疗经验。方法:回顾性分析2013年8月至2019年2月大连医科大学附属大连市儿童医院心脏中心收治的7例疑似原发性心脏肿瘤婴幼儿的诊治过程,患儿均行超声心动图等检查明确诊断,根据肿瘤的大小和位置选择治疗方案。出院后行随访观察。结果:7例患儿均经超声心动图诊断为原发性心脏肿瘤,其中2...