IMPORTANCE Li-Fraumeni syndrome is a cancer predisposition syndrome that is associated with a high, lifelong risk of a broad spectrum of cancers that is caused by pathogenic TP53 germline variants. A definition that reflects the broad phenotypic spectrum that has evolved since the gene discovery is lacking, and mechanisms leading to phenotypic differences remain largely unknown.OBJECTIVE To define the phenotypic spectrum of Li-Fraumeni syndrome and conduct phenotype-genotype associations across the phenotypic spectrum. DESIGN, SETTING, AND PARTICIPANTSWe analyzed and classified the germline variant data set of the International Agency for Research on Cancer TP53 database that contains data on a cohort of 3034 persons from 1282 families reported in the scientific literature since 1990. We defined the term Li-Fraumeni spectrum to encompass (1) phenotypic Li-Fraumeni syndrome, defined by the absence of a pathogenic/likely pathogenic TP53 variant in persons/families meeting clinical Li-Fraumeni syndrome criteria; (2) Li-Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in persons/families meeting Li-Fraumeni syndrome testing criteria; (3) attenuated Li-Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in a person/family with cancer who does not meet Li-Fraumeni syndrome testing criteria; and (4) incidental Li-Fraumeni syndrome, defined by the presence of a pathogenic/likely pathogenic TP53 variant in a person/family without a history of cancer. Data analysis occurred from November 2020 to March 2021. MAIN OUTCOMES AND MEASURESDifferences in variant distribution and cancer characteristics in patients with a germline TP53 variant who met vs did not meet Li-Fraumeni syndrome testing criteria. RESULTSTumor spectra showed significant differences, with more early adrenal (n = 166, 6.5% vs n = 0), brain (n = 360, 14.17% vs n = 57, 7.46%), connective tissue (n = 303, 11.92% vs n = 56, 7.33%), and bone tumors (n = 279, 10.98% vs n = 3, 0.39%) in patients who met Li-Fraumeni syndrome genetic testing criteria (n = 2139). Carriers who did not meet Li-Fraumeni syndrome genetic testing criteria (n = 678) had more breast (n = 292, 38.22% vs n = 700, 27.55%) and other cancers, 45% of them occurring after age 45 years. Hotspot variants were present in both groups. Several variants were exclusively found in patients with Li-Fraumeni syndrome, while others where exclusively found in patients with attenuated Li-Fraumeni syndrome. In patients who met Li-Fraumeni syndrome genetic testing criteria, most TP53 variants were classified as pathogenic/likely pathogenic (1757 of 2139, 82.2%), whereas 40.4% (404 of 678) of TP53 variants identified in patients who did not meet the Li-Fraumeni syndrome genetic testing criteria were classified as variants of uncertain significance, conflicting results, likely benign, benign, or unknown. CONCLUSIONS AND RELEVANCEThe findings of this cohort study suggest that this new classification, Li-Fraumeni spectrum, is a step toward ...

Growing evidence suggests that polymorphisms of genes coding for transporters or enzymes may partially explain the large between subject variability reported for methotrexate (MTX) pharmacokinetics (PK). This prospective study aimed to develop a population PK-pharmacogenetic model to evaluate the part of between-subject variability due to single-nucleotide polymorphisms (SNPs) in transporters and enzyme genes implicated in MTX distribution and elimination. MTX concentrations and 54 SNPs (located in ABCB1, ABCC1, ABCC2, ABCC3, ABCC4, ABCG2, SLC19A1, SLCO1B1, and UGT1A1 genes) were analyzed in patients treated with MTX included in the OS2006/sarcoma-09 trial (a multicenter, open-label, phase III trial, ClinicalTrials.gov. Identifier: NCT00470223). PK data were analyzed using the nonlinear mixed-effect modeling software program Monolix. The influence of each SNP was evaluated using a stepwise procedure under additive, recessive, or dominant genetic model. The likelihood ratio test was used to test the effect of each SNP on PK parameters. Overall, 187 patients with 7898 MTX blood concentrations were included in the PK-pharmacogenetic analysis. A 2-compartment model adequately described the data. Although high-dose MTX dosing recommendations in pediatric patients are currently based on body surface area, body weight was more predictive of clearance between-subject variability than body surface area. The most significant polymorphism associated with MTX clearance was rs13120400 (on the ABCG2 gene) under the recessive genetic model (P < .0001). GG genotype carriers for rs13120400 appeared to have a moderate decrease in MTX exposure compared to AA or GA carriers.

Little is known of the causes of childhood brain tumors (CBT). The aims of this study were to investigate whether extremes of birth weight were associated with increased risk of CBT and whether maternal preconceptional folic acid supplementation or breastfeeding reduced the risk. In addition, other maternal characteristics and birth related factors were also investigated. We pooled data from two French national population-based case-control studies with similar designs conducted in 2003-2004 and 2010-2011. The mothers of 510 CBT cases (directly recruited from the national childhood cancer register) and 3,102 controls aged under 15 years, frequency matched by age and gender did a telephone interview, which focussed on demographic and perinatal characteristics, and maternal life style habits and reproductive history. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusted for age, sex, study of origin and relevant confounders. No association was found between CBT and birth weight or fetal growth. The use of preconceptional folic acid supplementation was rare (5.3% in cases and 7.8% in controls) and the OR was 0.8 (95% CI 0.5, 1.4). There was no association with breastfeeding, even prolonged (six months or more; OR 1.0, 95% CI 0.8, 1.4). Neither was there any association between CBT and other investigated factors (maternal body mass index, gestational weight gain, congenital abnormality, maternal reproductive history or use of fertility treatments. Although large, this study was underpowered for subtype analyses. Pooling data with other population-based studies may provide further insight into findings by CBT subtypes.