A surgical case of pediatric spinal medulloepithelioma.

Embryonal tumor with multilayered rosettes (ETMR), C19MC-altered was introduced to the World Health Organization classification of central nervous system tumors in 2016. It is characterized by amplification or fusion of the chromosome 19 microRNA cluster (C19MC) locus at 19q13.42. Medulloepithelioma also an ETMR but lacks C19MC alteration. We report a rare case of spinal medulloepithelioma in a 2-year-old boy and review the literature.

A retrospective analysis of azacitidine treatment for juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a pediatric hematological malignancy with a poor prognosis. Although several case series have been published describing hematological and molecular responses to azacitidine (AZA) treatment in patients with JMML, the efficacy and safety profile of AZA is not well investigated, especially in Asian children and children undergoing hematopoietic stem cell transplantation (HSCT). We retrospectively analyzed 5 patients who received a total of 12 cycles (median 2 cycles) of AZA treatment in Japan. All five patients were boys and their ages at the time of treatment were 21, 23, 24, 26, and 46 months, respectively. All five patients tolerated AZA treatment, including four patients who received AZA after HSCT. Therapeutic toxicity with AZA was mostly limited to hematological toxicity. The only serious non-hematological adverse event was hyperbilirubinemia (grades III-IV) observed in a patient who received AZA after a second HSCT. Two out of five patients treated with AZA achieved a partial response (PR), while three patients treated for post-transplant relapse did not have an objective response. Future prospective studies should be conducted to develop combination therapies with AZA and other molecular targeted drugs for high-risk patients.

ALOX12 mutation in a family with dominantly inherited bleeding diathesis.

The arachidonic acid (AA) cascade plays a significant role in platelet aggregation. AA released from membrane phospholipids is metabolized by cyclooxygenase (COX) pathway to thromboxane A2 (TXA2) or by 12S-lipoxygenase (ALOX12) to 12-hydroperoxyeicosatetraenoic acid (12-HPETE). In contrast to a well-known role of the COX pathway in platelet aggregation, the role of ALOX12 is not well understood. Platelets of ALOX12-deficient mice exhibit increased sensitivity for ADP-induced aggregation. However, recent evidence strongly suggests a significant role of ALOX12 in platelet aggregation and calcium signaling. 12-HPETE potentiates thrombin- and thromboxane-induced platelet aggregation, and calcium signaling. Inhibition experiments of ALOX12 demonstrated decreased platelet aggregation and calcium signaling in stimulated platelets. We studied a family with a dominantly inherited bleeding diathesis using next-generation sequencing analysis. Platelet aggregation studies revealed that the proband's platelets had defective aggregation responses to ADP, TXA2 mimetic U46619, collagen, and AA, normal affinity of TXA2 receptor for U46619, and normal induction of GTPase activity upon stimulation with U46619. However, the production of inositol 1,4,5-triphosphate (IP3) was only increased up to 30% of the control upon U46619 stimulation, suggesting a defect in phospholipase C-ß2 (PLCB2) activation downstream from TXA2 receptors. Affected family members had no mutation of PLCB2, but had a heterozygous c.1946A > G (p.Tyr649Cys) mutation of ALOX12. ALOX12 activity in platelets from the affected members was decreased to 25-35% of the control. Our data strongly suggested that a heterozygous c.1946A > G ALOX12 mutation was a disease-causing mutation; however, further experiments are required to confirm the pathogenesis of ALOX12 mutation in platelet aggregation.

Three Consecutive Cases of Familial Hemophagocytic Lymphohistiocytosis, Including a Case Due to Maternal Uniparental Disomy.

We have experienced 3 consecutive cases of familial hemophagocytic lymphohistiocytosis (FHL). All affected infants had mutations in exon 3 of the perforin gene. The first had a homozygous mutation, c.1168C>T (p.R390*), caused by maternal uniparental isodisomy. The second and third had compound heterozygous mutations: c.781G>A (p.E261K) and c.1491T>A (p.C497*); c.1724G>T (p.C242G) and p.R390*, respectively. FHL is very rare in Northern Japan but should be suspected if infants exhibit prolonged fever. This is the first report of a relationship of p.R390* with FHL caused by uniparental isodisomy, and the second reported case of FHL type 2 with this form of inheritance.

Genotype-phenotype relationship in Japanese patients with congenital central hypoventilation syndrome.

Examine the genotype-phenotype relationship in Japanese congenital central hypoventilation syndrome (CCHS) patients and estimate the incidence of CCHS in Japan. Subjects were 92 Japanese patients with PHOX2B mutations; 19 cases carried 25 polyalanine repeat expansion mutations (PARMs); 67 cases carried 26 or more PARMs; and 6 had non-PARMs (NPARMs). We collected clinical data in all patients and estimated the development or intelligent quotients only in the patients carrying 25 PARM. The estimated incidence of CCHS was greater than one case per 148 000 births. Polyhydramnios was observed in three cases. Twelve infants exhibited depressed respiration at birth. In 19 cases carrying 25 PARM, the male-to-female ratio was ~3, no cases had Hirschsprung disease; 7 cases (37%) developed hypoventilation after the neonatal period, and 8 cases (42%) had mental retardation. In other 73 cases carrying 26 or more PARMs or NPARMs, male-to-female ratio was equal; patients frequently complicated with Hirschsprung disease and constipation, and all patients presented with hypoventilation in the neonatal period. Clinical symptoms were severe in most patients carrying long PARMs and NPARMs. In 25 PARM, additional genetic and/or epigenetic factors were required for CCHS development and male sex is likely a predisposing factor. The patients carrying 25 PARM frequently had mental retardation likely because they were not able to receive appropriate ventilation support following a definitive diagnosis owing to subtle and or irregular hypoventilation. Molecular diagnosis provides a definitive diagnosis and enables to receive appropriate ventilator support.

Successful treatment of acute myeloid leukaemia in a patient with ataxia telangiectasia.

Ataxia telangiectasia (AT) is a rare autosomal recessive multisystem disorder characterised by cerebellar degeneration, immunodeficiency and cancer predisposition. Around 10% of AT patients develop lymphoid malignancies, but the development of myeloid leukaemia with AT (AT-AML) is extremely rare, and there have been no previous publications regarding suitable therapies. Here, we first describe a successful therapeutic experience in a patient with AT-AML (FAB-M1) who attained remission after induction therapy and maintained stable disease for a year. To minimise therapy-induced toxicity, low-dose induction was applied first, though this was obviously insufficient and the patient subsequently responded well to dose-intensified short-term chemotherapy. In this report, we suggest a curative therapeutic approach for AT-AML, though the issue of how best to manage patients with cancer complicated by immunodeficiency remains undecided.

Inheritance of polyalanine expansion mutation of PHOX2B in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS; MIM 209880) is caused mostly by dominant alanine expansion (most prevalent is 7-alanine expansion) mutations in PHOX2B. More than 90% of the alanine expansion mutations had been considered to be de novo due to unequal crossover during gametogenesis. However, a recent report stated that 25% of patients inherited the alanine-expanded allele from their parents with somatic mosaicism or constitutive mutation. We studied inheritance in 45 unrelated families, and found that one patient (2%) inherited 5-alanine expansion mutation from a parent with late-onset central hypoventilation syndrome and nine patients (20%) inherited 5- to 7-alanine expansion mutation from apparently asymptomatic parents with somatic mosaicism. Analysis using a sensitive method would be recommended to all parents of CCHS proband due to high incidence of somatic mosaicism. The absence of an alanine-contracted allele (expected counterpart allele in unequal crossover) and the highest prevalence of 6-alanine expansion mutation in somatic mosaicism suggest that the somatic mosaicism is likely caused by a mechanism other than an unequal crossover, such as a replication mechanism.

New signaling pathway for parathyroid hormone and cyclic AMP action on extracellular-regulated kinase and cell proliferation in bone cells. Checkpoint of modulation by cyclic AMP.

cAMP signaling, activated by extracellular stimuli such as parathyroid hormone, has cell type-specific effects important for cellular proliferation and differentiation in bone cells. Recent evidence of a second enzyme target for cAMP suggests divergent effects on extracellular-regulated kinase (ERK) activity depending on Epac/Rap1/B-Raf signaling. We investigated the molecular mechanism of the dual functionality of cAMP on cell proliferation in clonal bone cell types. MC3T3-E1 and ATDC5, but not MG63, express a 95-kDa isoform of B-Raf. cAMP stimulated Ras-independent and Rap1-dependent ERK phosphorylation and cell proliferation in B-Raf-expressing cells, but inhibited growth in B-Raf-lacking cells. The mitogenic action of cAMP was blocked by the ERK pathway inhibitor PD98059. In B-Raf-transduced MG63 cells, cAMP stimulated ERK activation and cell proliferation. Thus, B-Raf is the dominant molecular switch that permits differential cAMP-dependent regulation of ERK with important implications for cell proliferation in bone cells. These findings might explain the dual functionality of parathyroid hormone on osteoblastic cell proliferation.