Constitutional 2p16.3 deletion including MSH6 and FBXO11 in a boy with developmental delay and diffuse large B-cell lymphoma.

We describe a case of a boy with neurodevelopmental delay and a diffuse large B-cell lymphoma (DLBCL) in whom we discovered a germline de novo 2p16.3 deletion including MSH6 and part of the FBXO11 gene. A causative role for MSH6 in cancer development was excluded based on tumor characteristics. The constitutional FBXO11 deletion explains the neurodevelopmental delay in the patient. The FBXO11 protein is involved in BCL-6 ubiquitination and BCL-6 is required for the germinal center reaction resulting in B cell differentiation. Somatic loss of function alterations of FBXO11 result in BCL-6 overexpression which is a known driver in DLBCL. We therefore consider that a causative relationship between the germline FBXO11 deletion and the development of DLBCL in this boy is conceivable.

Genomic profiling of Acute lymphoblastic leukemia in ataxia telangiectasia patients reveals tight link between ATM mutations and chromothripsis.

Recent developments in sequencing technologies led to the discovery of a novel form of genomic instability, termed chromothripsis. This catastrophic genomic event, involved in tumorigenesis, is characterized by tens to hundreds of simultaneously acquired locally clustered rearrangements on one chromosome. We hypothesized that leukemias developing in individuals with Ataxia Telangiectasia, who are born with two mutated copies of the ATM gene, an essential guardian of genome stability, would show a higher prevalence of chromothripsis due to the associated defect in DNA double-strand break repair. Using whole-genome sequencing, fluorescence in situ hybridization and RNA sequencing, we characterized the genomic landscape of Acute Lymphoblastic Leukemia (ALL) arising in patients with Ataxia Telangiectasia. We detected a high frequency of chromothriptic events in these tumors, specifically on acrocentric chromosomes, as compared with tumors from individuals with other types of DNA repair syndromes (27 cases total, 10 with Ataxia Telangiectasia). Our data suggest that the genomic landscape of Ataxia Telangiectasia ALL is clearly distinct from that of sporadic ALL. Mechanistically, short telomeres and compromised DNA damage response in cells of Ataxia Telangiectasia patients may be linked with frequent chromothripsis. Furthermore, we show that ATM loss is associated with increased chromothripsis prevalence in additional tumor entities.

Childhood neuroendocrine tumours: a descriptive study revealing clues for genetic predisposition.

BACKGROUND: Neuroendocrine tumours (NETs) are rare in children and limited data are available. We aimed to specify tumour and patient characteristics and to investigate the role of genetic predisposition in the aetiology of paediatric NETs. METHODS: Using the Dutch Pathology Registry PALGA, we collected patient- and tumour data of paediatric NETs in the Netherlands between 1991 and 2013 (N=483). RESULTS: The incidence of paediatric NETs in the Netherlands is 5.40 per one million per year. The majority of NETs were appendiceal tumours (N=441;91.3%). Additional surgery in appendiceal NETs was indicated in 89 patients, but performed in only 27 of these patients. Four out of five patients with pancreatic NETs were diagnosed with Von Hippel-Lindau disease (N=2) and Multiple Endocrine Neoplasia type 1 (N=2). In one patient with an appendiceal NET Familial Adenomatous Polyposis was diagnosed. On the basis of second primary tumours or other additional diagnoses, involvement of genetic predisposition was suggestive in several others. CONCLUSIONS: We identified a significant number of patients with a confirmed or suspected tumour predisposition syndrome and show that paediatric pancreatic NETs in particular are associated with genetic syndromes. In addition, we conclude that treatment guidelines for appendiceal paediatric NETs need revision and improved implementation.

Treatment of acute leukemia in children with ataxia telangiectasia (A-T).

Early onset ataxia telangiectasia (A-T) is a neurodegenerative DNA-instability disorder, which presents early in childhood. Hallmarks of A-T are progressive ataxia and a dramatic increased risk of developing malignancies (25%), especially of hematological origin. In children these malignancies mainly concern aggressive Non-Hodgkin lymphoma, acute leukemias and Hodgkin lymphoma. Of the acute leukemias, T-cell lymphoblastic leukemia (T-ALL) is by far the most common. Since patients with A-T experience increased toxicity to radio- and chemotherapeutic treatment, the optimal treatment strategy of acute leukemia remains subject of debate. Review of literature of treatment of T-ALL in patients with A-T (n = 18) showed that many patients are not diagnosed with A-T at time of presentation of T-ALL. This implicates that physicians must be aware of symptoms of A-T in young patients presenting with T-ALL. Complete remission rates are high following upfront modified as well as unmodified treatment strategies. Treatment of ALL in children with A-T is feasible and should be performed. Definitive treatment strategy must be determined by shared decision making with patient, caretakers and medical team. Future prospective studies are needed to elucidate optimal treatment strategy.

Adrenocortical carcinoma in children: first population-based clinicopathological study with long-term follow-up.

Adrenocortical carcinoma (ACC) is rare in both adult and pediatric populations. Literature suggests significant differences between children and adults in presentation, histological properties and outcome. The aim of this first nationwide study on pediatric ACC was to describe the incidence, presentation, pathological characteristics, treatment and survival in The Netherlands. All ACC patients aged <20 years at diagnosis and registered in the population-based Netherlands Cancer Registry between 1993 and 2010 were included. Clinical data were extracted from medical records. Archival histological slides were collected via the Dutch Pathology Registry (PALGA). We compared our findings to all clinical studies on pediatric ACC that were found on PubMed. Based on the results, 12 patients were identified: 8 females and 4 males. The median age was 4.1 years (range 1.1-18.6). The population-based age-standardized incidence rate for patients <20 years was 0.18 per million person-years. Autonomous hormonal secretion was present in 10 patients. Seven patients were aged ≤4 years at diagnosis, 5 presented with localized disease and 2 with locally advanced disease. Five patients were aged ≥5 years, 3 presented with distant metastases and 1 with locally advanced disease. For all patients, histological examination displayed malignant characteristics. All patients aged ≤4 years at diagnosis survived; the median follow-up was 97 months (57-179 months). All patients aged ≥5 years died; the median survival was 6 months (0-38 months). Pediatric ACC is extremely rare in the Western world. The clinical outcome was remarkably better in patients aged ≤4 years. This is in accordance with less advanced stage of disease at presentation, yet contrasts with the presence of adverse histological characteristics. Clinical management in advanced disease is adapted from adult practice in the absence of evidence regarding pediatric ACC.

Guidelines for surveillance of individuals with constitutional mismatch repair-deficiency proposed by the European Consortium "Care for CMMR-D" (C4CMMR-D).

Lynch syndrome (LS) is an autosomal dominant disorder caused by a defect in one of the DNA mismatch repair genes: MLH1, MSH2, MSH6 and PMS2. In the last 15 years, an increasing number of patients have been described with biallelic mismatch repair gene mutations causing a syndrome referred to as 'constitutional mismatch repair-deficiency' (CMMR-D). The spectrum of cancers observed in this syndrome differs from that found in LS, as about half develop brain tumours, around half develop digestive tract cancers and a third develop haematological malignancies. Brain tumours and haematological malignancies are mainly diagnosed in the first decade of life, and colorectal cancer (CRC) and small bowel cancer in the second and third decades of life. Surveillance for CRC in patients with LS is very effective. Therefore, an important question is whether surveillance for the most common CMMR-D-associated cancers will also be effective. Recently, a new European consortium was established with the aim of improving care for patients with CMMR-D. At a workshop of this group held in Paris in June 2013, one of the issues addressed was the development of surveillance guidelines. In 1968, criteria were proposed by WHO that should be met prior to the implementation of screening programmes. These criteria were used to assess surveillance in CMMR-D. The evaluation showed that surveillance for CRC is the only part of the programme that largely complies with the WHO criteria. The values of all other suggested screening protocols are unknown. In particular, it is questionable whether surveillance for haematological malignancies improves the already favourable outcome for patients with these tumours. Based on the available knowledge and the discussions at the workshop, the European consortium proposed a surveillance protocol. Prospective collection of all results of the surveillance is needed to evaluate the effectiveness of the programme.

High-quality care for all children with cancer.

BACKGROUND: Providing high-quality care for children with cancer could improve treatment outcomes, survival and quality of life of the children and parents. The aim of this study is to select high-quality care recommendations for all children with cancer based on literature and consensus for future development of quality indicators. MATERIALS AND METHODS: We performed an extensive search in databases for scientific literature and in websites of international health care and guideline development organizations to create an inventory of recommendations for the care for all children with cancer. The RAND modified Delphi method was used to grade and select recommendations for high-quality care. RESULTS: Our search resulted in a list of 131 recommendations on care for all children with cancer. The expert panel graded, discussed and prioritized these recommendations. Analysis of these ratings resulted ultimately in a list of 109 high-quality care recommendations for all children with cancer, including 31 prioritized recommendations. CONCLUSIONS: This study defines a set of high-quality care recommendations based on literature and consensus. These recommendations provide a basis for the development of a comprehensive set of quality indicators to evaluate care in paediatric oncology.

[Ovarian tumour in a girl with chronic abdominal pain and distension]. / Ovariumtumor bij een meisje met chronische buikpijn en zwelling van de buik.

A 12-year-old girl presented with chronic abdominal pain and distension that had persisted for 6 and 3 months, respectively. The cause was a Sertoli-Leydig cell tumour originating in the left ovary. The cyst and ovary were resected. The patient recovered and was asymptomatic 2 years after the operation. Ovarian tumours are rarely seen in children. The sex cordstromal tumours constitute a heterogeneous subgroup. Two of the most frequently observed sex cord-stromal tumours are the juvenile granulosa cell tumour and the Sertoli-Leydig cell tumour. Even though these tumours may contain histologically malignant characteristics, their behaviour is usually benign. Clinical characteristics are endocrine symptoms, fatigue, chronic abdominal pain and abdominal distension. In addition, pressure from the tumour mass may result in symptoms in adjacent organ systems. Surgical excision is usually curative. Patients with advanced disease may benefit from adjuvant chemotherapy. Chronic abdominal pain is frequently observed in children and, in some rare cases, may be caused by ovarian tumours.

Fumarase deficiency presenting with periventricular cysts.

A fumarase-deficient patient expressed a novel phenotype of congenital cerebral ventricular dilatation and periventricular cysts. The patient was a compound heterozygote for two mutations that are the only ones among the 12 published mutations that have been found in multiple, unrelated, fumarase-deficient patients.

Mutations in the complex I NDUFS2 gene of patients with cardiomyopathy and encephalomyopathy.

Human complex I is built up and regulated by genes encoded by the mitochondrial DNA (mtDNA) as well as the nuclear DNA (nDNA). In recent years, attention mainly focused on the relation between complex I deficiency and mtDNA mutations. However, a high percentage of consanguinity and an autosomal-recessive mode of inheritance observed within our patient group as well as the absence of common mtDNA mutations make a nuclear genetic cause likely. The NDUFS2 protein is part of complex I of many pro- and eukaryotes. The nuclear gene coding for this protein is therefore an important candidate for mutational detection studies in enzymatic complex I deficient patients. Screening of patient NDUFS2 cDNA by reverse transcriptase-polymerase chain reaction (RT-PCR) in combination with direct DNA sequencing revealed three missense mutations resulting in the substitution of conserved amino acids in three families.

Characterization of the human complex I NDUFB7 and 17.2-kDa cDNAs and mutational analysis of 19 genes of the HP fraction in complex I-deficient-patients.

Deficiency of NADH:ubiquinone oxidoreductase, the first enzyme complex of the mitochondrial respiratory chain, is one of the most frequent causes of human mitochondrial encephalomyopathies. A relatively small percentage of human complex I deficiency is associated with mitochondrial DNA mutations. cDNA characterization and mutational analysis of the structural complex I genes in 19 complex I-deficient patients, in whom common mtDNA mutations have been excluded, has so far revealed five patients with alterations in evolutionary conserved nuclear-encoded proteins. In order to complete our knowledge about the expected 36 structural nuclear complex I genes, we characterized the NDUFB7 and the 17.2-kDa cDNA sequences of the hydrophobic (HP) fraction of the complex. Subsequently, we screened all subunits of this fraction for the presence of mutations in those 14 patients of our initial patient cohort in whom the underlying genetic cause had not been elucidated. Strikingly, no pathogenic mutations were found in the HP subunits that would explain the complex I deficiency in our patients. Other strategies are needed to unravel proteins involved in the pathogenesis of the complicated cellular network of transcription until correct assemblage of complex I.

Isolated complex I deficiency in children: clinical, biochemical and genetic aspects.

We retrospectively examined clinical and biochemical characteristics of 27 patients with isolated enzymatic complex I deficiency (established in cultured skin fibroblasts) in whom common pathogenic mtDNA point mutations and major rearrangements were absent. Clinical phenotypes present in this group are Leigh syndrome (n = 7), Leigh-like syndrome (n = 6), fatal infantile lactic acidosis (n = 3), neonatal cardiomyopathy with lactic acidosis (n = 3), macrocephaly with progressive leukodystrophy (n = 2), and a residual group of unspecified encephalomyopathy (n = 6) subdivided into progressive (n = 4) and stable (n = 2) variants. Isolated complex I deficiency is one of the most frequently observed disturbance of the OXPHOS system. Respiratory chain enzyme assays performed in cultured fibroblasts and skeletal muscle tissue in general reveal similar results, but for complete diagnostics we recommend enzyme measurements performed in at least two different tissues to minimize the possibility of overlooking the enzymatic diagnosis. Lactate levels in blood and CSF and cerebral CT/MRI studies are highly informative, although normal findings do not exclude complex I deficiency. With the discovery of mutations in nuclear encoded complex I subunits, adequate pre- and postnatal counseling becomes available. Finally, considering information currently available, isolated complex I deficiency in children seems to be caused in the majority by mutations in nuclear DNA.

Leigh syndrome associated with a mutation in the NDUFS7 (PSST) nuclear encoded subunit of complex I.

Leigh syndrome is the phenotypical expression of a genetically heterogeneous cluster of disorders, with pyruvate dehydrogenase complex deficiency and respiratory chain disorders as the main biochemical causes. We report the first missense mutation within the nuclear encoded complex I subunit, NDUFS7, in 2 siblings with neuropathologically proven complex I-deficient Leigh syndrome.

The human nuclear-encoded acyl carrier subunit (NDUFAB1) of the mitochondrial complex I in human pathology.

We present the cDNA sequence of the human mitochondrial acyl carrier protein NDUFAB1, a nuclear-encoded subunit of complex I of the mitochondrial respiratory chain. We obtained the NDUFAB1 cDNA using the cDNA sequence of the bovine mitochondrial acyl carrier protein. The human cDNA contains two putative translation initiation codons. The human NDUFAB1 protein contains a phosphopantetheine attachment site (DLGLDSLDQVEIIMAM), unique for acyl carrier proteins, and an EF-hand calcium binding domain (DIDAEKLMCPQEI). Transcripts of this gene are found in a wide range of human tissues. The highests expression levels were observed, in descending order, in adult heart, skeletal muscle and fetal heart. We subjected NDUFAB1 fibroblast cDNA of 20 patients with an isolated enzymatic complex I deficiency to mutational detection. No mutations in the NDUFAB1 open reading frame were observed. Future studies will answer whether mutations in the NDUFAB1 promoter or transcription elements are responsible for the observed complex I deficiency.

The human NADH: ubiquinone oxidoreductase NDUFS5 (15 kDa) subunit: cDNA cloning, chromosomal localization, tissue distribution and the absence of mutations in isolated complex I-deficient patients.

We have cloned the cDNA of the NDUFS5 subunit (15 kDa) of the human mitochondrial respiratory chain complex NADH: ubiquinone oxidoreductase (complex I). The open reading frame consists of 321 base-pairs, coding for 106 amino acids, with a calculated molecular mass of 12.5 kDa. There is an 81.0% identity with the bovine equivalent on cDNA level and 74.5% identity on amino acid basis. PCR analysis of rodent-human somatic cell hybrids revealed that the human NDUFS5 gene maps to chromosome 1. The NDUFS5 mRNA is expressed ubiquitously in human tissues, with a relative higher expression in human heart, skeletal muscle, liver, kidney and fetal heart. A mutation detection study of twenty isolated enzymatic complex I-deficient patients revealed no mutations, nor polymorphisms.

The first nuclear-encoded complex I mutation in a patient with Leigh syndrome.

Nicotinamide adenine dinucleotide (NADH):ubiquinone oxidoreductase (complex I) is the largest multiprotein enzyme complex of the respiratory chain. The nuclear-encoded NDUFS8 (TYKY) subunit of complex I is highly conserved among eukaryotes and prokaryotes and contains two 4Fe4S ferredoxin consensus patterns, which have long been thought to provide the binding site for the iron-sulfur cluster N-2. The NDUFS8 cDNA contains an open reading frame of 633 bp, coding for 210 amino acids. Cycle sequencing of amplified NDUFS8 cDNA of 20 patients with isolated enzymatic complex I deficiency revealed two compound heterozygous transitions in a patient with neuropathologically proven Leigh syndrome. The first mutation was a C236T (P79L), and the second mutation was a G305A (R102H). Both mutations were absent in 70 control alleles and cosegregated within the family. A progressive clinical phenotype proceeding to death in the first months of life was expressed in the patient. In the 19 other patients with enzymatic complex I deficiency, no mutations were found in the NDUFS8 cDNA. This article describes the first molecular genetic link between a nuclear-encoded subunit of complex I and Leigh syndrome.

The nuclear-encoded human NADH:ubiquinone oxidoreductase NDUFA8 subunit: cDNA cloning, chromosomal localization, tissue distribution, and mutation detection in complex-I-deficient patients.

We report the cloning of the cDNA sequence of the nuclear-encoded NDUFA8 subunit of NADH: ubiquinone oxidoreductase, the first mitochondrial respiratory chain complex. The NDUFA8 open reading frame (ORF) includes 519 bp and encodes 172 amino acids (Mr=20.1 kDa). The human cDNA sequence shows 86.2% identity with the bovine sequence, whereas the human NDUFA8 amino acid sequence is 87.8% similar to its bovine PGIV protein counterpart. Both human and bovine NDUFA8 contain a conserved cysteine motif. Polymerase chain reaction analysis of rodent/human somatic cell hybrids maps the human NDUFA8 gene to chromosome 9. A multiple tissue blot has revealed the highest NDUFA8 mRNA expression in human heart, skeletal muscle, and fetal heart. Mutation analysis of the NDUFA8 fibroblast cDNA in 20 patients with an isolated enzymatic complex I deficiency in cultured skin fibroblasts has revealed two polymorphisms, one within the ORF and the other in the 3' untranslated region of the NDUFA8 cDNA sequence. The allelic frequency of both polymorphisms was similar in controls and complex-I-deficient patients.

Molecular characterization and mutational analysis of the human B17 subunit of the mitochondrial respiratory chain complex I.

Bovine NADH:ubiquinone oxidoreductase (complex 1) of the mitochondrial respiratory chain consists of about 36 nuclear-encoded subunits. We review the current knowledge of the 15 human complex I subunits cloned so far, and report the 598-bp cDNA sequence, the chromosomal localization and the tissue expression of an additional subunit, the B17 subunit. The cDNA open reading frame of B17 comprises 387 bp and encodes a protein of 128 amino acids (calculated Mr 15.5 kDa). There is 82.7% and 78.1% homology, respectively, at the cDNA and amino acid level with the bovine counterpart. The gene of the B17 subunit has been mapped to chromosome 2. Multiple-tissue dot-blots showed ubiquitous expression of the mRNA with relatively higher expression in tissues known for their high energy demand. Of these, kidney showed the highest expression. Mutational analysis of the subunit revealed no mutations or polymorphisms in 20 patients with isolated enzymatic complex I deficiency in cultured skin fibroblasts.

Nuclear genes of human complex I of the mitochondrial electron transport chain: state of the art.

The mitochondrial electron transport chain (mtETC) consists of four multi-subunit enzyme complexes. Complex I or NADH:ubiquinone oxidoreductase, the largest mtETC multisubunit complex, consists of approximately 41 subunits. Seven of these subunits are encoded by the mitochondrial genome, the remainder by the nuclear genome. Among the mitochondriocytopathies, complex I deficiencies are encountered frequently. Although some complex I deficiencies have been associated with mitochondrial DNA mutations, the genetic defect has not been elucidated in the majority of complex I-deficient patients. It is expected that many of these patients have mutations in the nuclear-encoded subunits of this complex, so vital for cellular energy production. After a brief summary of the current knowledge of complex I from cow, bacteria and fungi, this review presents the state of the art of the knowledge of the human nuclear-encoded complex I genes which, in the last 18 months, has made enormous progress. At present, the complete gene structure of four subunits and the cDNA structure of 18 of the 34 complex I nuclear-encoded subunits are known. Mapping of these subunits shows a random distribution over the chromosomes. The chromosomal localization is known for 14 complex I genes. Recently, the first mutation, a 5 bp duplication in the 18 kDa (AQDQ) subunit, has been reported. We expect that within 1 year all human nuclear-encoded complex I subunits will be cloned. Mutational analysis of these subunits is warranted in complex I-deficient patients and will not only be important for genetic counselling but will also extend the knowledge regarding the functional properties of the individual human complex I subunits.