Maruša Debeljak

High prevalence of thyroid peroxidase gene mutations in patients with thyroid dyshormonogenesis

OBJECTIVE Thyroid dyshormonogenesis is a genetically heterogeneous group of inherited disorders in the enzymatic cascade of thyroid hormone synthesis that result in congenital hypothyroidism (CH). Thyroid peroxidase gene (TPO) mutations are one of the most common causes of thyroid dyshormonogenesis. The aim of this study was to identify TPO gene defects in a cohort of patients with thyroid dyshormonogenesis from Slovenia, Bosnia, and Slovakia. DESIGN AND METHODS Forty-three patients with permanent CH and orthoptic thyroid glands from 39 unrelated families participated in the study. Mutational analysis of the TPO gene and part of its promoter consisted of single-stranded conformation polymorphism analysis, sequencing, and restriction fragment length polymorphism (RFLP) analysis. RESULTS TPO gene mutations were identified in 46% of participants. Seven different mutations were identified, four mutations of these being novel, namely 613C > T (R175X), 1519_1539del (A477_N483del), 2089G > A (G667S), and 2669G > A (G860R). Only a single allele mutation was identified in 65% of the TPO mutation carriers. CONCLUSIONS The results showed a higher prevalence of TPO gene mutations in thyroid dyshormonogenesis when compared with published studies. The high percentage of single allele mutations implied possible intronic or regulatory TPO gene mutations or monoallelic expression.

Influence of the polymorphism in candidate genes on late cardiac damage in patients treated due to acute leukemia in childhood

Anthracyclines have contributed significantly to the increased cure rate in pediatric oncology. Cardiac toxicity is an important late effect after anthracycline treatment and is thought to occur by reactive oxygen species mediated cardiac damage. We hypothesized that deactivating variants of superoxide dismutase II (SOD2) [rs4880 (−9Val > Ala)], catalase (CAT) [rs1001179 (−262C > T) and rs10836235 (c.66 + 78C > T)], GSTT1, and GSTM1 may increase the risk of developing cardiac toxicity, in patients exposed to anthracyclines. The hypothesis was tested in a cohort of 76 long-term survivals of acute lymphoblastic leukemia in childhood. Cardiac damage was evaluated as an attributive variable and compared to gene polymorphisms. In our study group, we show statistically significant correlation between CC homozygosity for CAT (rs10836235 (c.66 + 78C > T)) and cardiac damage after anthracycline exposure (p = 0.020). We found no statistically significant correlation between cardiac damage after anthracycline exposure and deactivating variants of SOD2 [rs4880 (−9Val > Ala)], CAT [rs1001179 (−262C > T), GSTT1, and GSTM1.

Influence of folate pathway polymorphisms on high-dose methotrexate-related toxicity and survival in childhood acute lymphoblastic leukemia

Abstract The prediction of high-dose methotrexate (HD-MTX) toxicity is a key issue in the individualization of treatment in childhood acute lymphoblastic leukemia (ALL). Our aim was to evaluate the influence of MTX pathway polymorphisms on HD-MTX treat- ment outcome in children with ALL. In total, 167 children with ALL were genotyped for methylenetetrahydrofolate dehydrogenase (MTHFD1) 1958G > A, methylenetetrahydrofolate reductase (MTHFR) 677C > T and 1298A > C and thymidylate synthase (TYMS) 2R > 3R polymorphisms. The MTHFD1 1958A allele significantly reduced the odds of hepatotoxicity (adjusted p = 0.009), while the TYMS 3R allele significantly reduced the odds of leukocytopenia and thrombocytopenia (adjusted p = 0.005 and adjusted p = 0.002, respectively). MTHFR polymorphisms did not influence HD-MTX-related toxicity, but a significant effect of MTHFR 677C > T–TYMS 2R > 3R and MTHFD1 1958G > A–MTHFR 677C > T interactions on HD-MTX-related toxicity was observed. None of the investigated polymorphisms influenced survival. Our study suggests an important role of polymorphisms and gene–gene interactions within the folate pathway in HD-MTX-related toxicity in childhood ALL.

Clinical Features and Genetic Background of the Periodic Fever Syndrome with Aphthous Stomatitis, Pharyngitis, and Adenitis: A Single Center Longitudinal Study of 81 Patients

PFAPA syndrome is the most common autoinflammatory disorder in childhood with unknown etiology. The aim of our study was clinical evaluation of PFAPA patients from a single tertiary care center and to determine whether variations of AIM2, MEFV, NLRP3, and MVK genes are involved in PFAPA pathogenesis. Clinical and laboratory data of consecutive patients with PFAPA syndrome followed up at the University Childrens Hospital, Ljubljana, were collected from 2008 to 2014. All four genes were PCR amplified and directly sequenced. Eighty-one patients fulfilled criteria for PFAPA syndrome, 50 (63%) boys and 31 (37%) girls, with mean age at disease onset of 2.1 ± 1.5 years. Adenitis, pharyngitis, and aphthae were present in 94%, 98%, and 56%, respectively. Family history of recurrent fevers in childhood was positive in 78%. Nineteen variants were found in 17/62 (27%) patients, 4 different variants in NLRP3 gene in 13 patients, and 6 different variants in MEFV gene in 5 patients, and 2 patients had 2 different variants. No variants of clinical significance were found in MVK and AIM2 genes. Our data suggest that PFAPA could be the result of multiple low-penetrant variants in different genes in combination with epigenetic and environmental factors leading to uniform clinical picture.

Benign familial neonatal convulsions caused by mutation in KCNQ3, exon 6: A European case

Benign familial neonatal convulsions (BFNC) is a rare, clinically and genetically heterogenous epileptic disorder. Two voltage gated potassium genes, KCNQ2 and KCNQ3, have been identified as genes responsible for BFNC1 and BFNC2 respectively. While as many as 73 mutations of KCNQ2 have been described up to date, only 4 mutations in KCNQ3, 3 of them appearing in exon 5, have been identified. Mutation in exon 6 was found for the first time in a Chinese family, and here we report the same missense mutation of KCNQ3 within exon 6 in a Caucasian family, whose history and clinical picture were in accordance with BFNC.

A patient with Baller-Gerold syndrome and midline NK/T lymphoma.

Three autosomal recessive disorders are associated with mutations in the RECQL4 gene: Rothmund–Thomson syndrome (RTS), Baller–Gerold syndrome (BGS), and RAPADILINO syndrome. BGS is characterized by two major clinical abnormalities: craniosynostosis and preaxial limb anomalies but not cancer development. We performed RECQL4 mutation detection in a patient with BGS and several clinical signs of RTS who developed a midline NK/T‐cell lymphoma. Sequencing was used to identify RECQL4 mutations, and RNA analysis was used to examine expression of mRNA in leukocytes. The patient was found to be compound heterozygous for two mutations in exon 15, namely c.[2492_2493delAT] + c.[2506_2518del13bp]. We found that only the allele with 13 bp deletion was expressed in blood leukocytes. Our patient showed severe phenotypic abnormalities, with clinical signs of both BGS and RTS. She developed an extranodal NK/T‐cell lymphoma, which is extremely rare in children of her age and is the first described case of BGS with development of a cancer. This case of a RECQL4‐related disorder highlights the significant phenotypic overlap between the classically delineated RECQL4‐associated syndromes and questions the need to redefine or combine these clinical entities.

No evidence of association of methylenetetrahydrofolate reductase polymorphism with occurrence of second neoplasms after treatment of childhood leukemia.

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms have been associated not only with the risk for acute lymphoblastic leukemia (ALL) in adults and children, but also with increased methotrexate toxicity. The present study aimed to investigate whether MTHFR polymorphisms modify the risk for development of secondary malignancies in children treated for ALL with protocols that included high-dose methotrexate. MTHFR genotypes were determined in DNA samples isolated from archived bone marrow smears of 15 patients with a second malignancy and a matched control group of 30 patients who did not developed a second malignancy after the treatment for ALL. The frequencies of MTHFR C677T and A1298C genotypes in all patients were: C677T: CC 40%, CT 46.7% and TT 13.3% and A1298C: AA 46.7%, AC 44.4% and CC 8.9%. The relative risk for second malignancy was not significantly increased in ALL patients having at least one polymorphic C667T [odds ratio (OR) 1.51; 95% confidence interval (CI) 0.43-5.31] or one polymorphic A1298C allele (OR 1; 95% CI 0.29?-?3.46). Our study suggests that MTHFR polymorphisms are not associated with increased risk of second cancer in children treated with high-dose methotrexate.

Polymorphisms in GRIA1 gene are a risk factor for asparaginase hypersensitivity during the treatment of childhood acute lymphoblastic leukemia.

l-asparaginase is an effective antineoplastic agent used in chemotherapy of acute lymphoblastic leukemia. The drug effect may be compromised by an elicited immune response, resulting in the production of anti-asparaginase antibodies causing an anaphylactic reaction or silent inactivation of the enzyme. To elucidate possible genetic predisposition for inter-individual differences in asparaginase hypersensitivity, we studied single nucleotide polymorphisms (SNPs) in the GRIA1 gene in 146 pediatric patients treated with l-asparaginase. Allergic reaction to l-asparaginase occurred in 49.3% of patients. We observed a statistically significant association between SNPs in the GRIA1 gene and the occurrence of asparaginase allergy: rs4958351 with p = 0.003, rs4958676 with p = 0.005, rs6889909 with p = 0.005, rs6890057 with p = 0.005 and rs10070447 with p = 0.006. We found a statistically significant correlation between asparaginase allergy and event-free survival (p-value 0.005).

Concordant acute myeloblastic leukemia in monozygotic twins with germline and shared somatic mutations in the gene for CCAAT-enhancer-binding protein α with 13 years difference at onset

Since the first report,[1][1] very few monozygotic pairs of twins with concordant leukemia have been described.[2][2] The interval between the onset of overt disease in each of the twins usually varies from some months to some years.[2][2] Genetic changes in childhood acute leukemia are highly

A case report of short-chain acyl-CoA dehydrogenase deficiency (SCADD)

Background Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare inherited mitochondrial fatty acid oxidation disorder associated with variations in the ACADS (Acyl-CoA dehydrogenase, C-2 to C-3 short chain) gene. SCADD has highly variable biochemical, genetic and clinical characteristics. Phenotypes vary from fatal metabolic decompensation to asymptomatic individuals. Subject and methods A Romani boy presented at 3 days after birth with hypoglycaemia, hypotonia and respiratory pauses with brief generalized seizures. Afterwards the failure to thrive and developmental delay were present. Organic acids analysis with gas chromatography-mass spectrometry (GS/MS) in urine and acylcarnitines analysis with liquid chromatography-tandem mass spectrometry (LC-MS/MS) in dried blood spot were measured. Deoxyribonucleic acid (DNA) was isolated from blood and polymerase chain reactions (PCRs) were performed for all exons. Sequence analysis of all exons and flanking intron sequences of ACADS gene was performed. Results Organic acids analysis revealed increased concentration of ethylmalonic acid. Acylcarnitines analysis showed increase of butyrylcarnitine, C4-carnitine. C4-carnitine was 3.5 times above the reference range (<0.68 µmol/L). Confirmation analysis for organic acids and acylcarnitine profile was performed on the second independent sample and showed the same pattern of increased metabolites. Sequence analysis revealed 3-bp deletion at position 310-312 in homozygous state (c.310_312delGAG). Mutation was previously described as pathogenic in heterozygous state, while it is in homozygous state in our patient. Conclusions In our case clinical features of a patient, biochemical parameters and genetic data were consistent and showed definitely SCAD deficiency.