Takahiro Okutani

Gain-of-function mutations in RIT1 cause Noonan syndrome, a RAS/MAPK pathway syndrome.

RAS GTPases mediate a wide variety of cellular functions, including cell proliferation, survival, and differentiation. Recent studies have revealed that germline mutations and mosaicism for classical RAS mutations, including those in HRAS, KRAS, and NRAS, cause a wide spectrum of genetic disorders. These include Noonan syndrome and related disorders (RAS/mitogen-activated protein kinase [RAS/MAPK] pathway syndromes, or RASopathies), nevus sebaceous, and Schimmelpenning syndrome. In the present study, we identified a total of nine missense, nonsynonymous mutations in RIT1, encoding a member of the RAS subfamily, in 17 of 180 individuals (9%) with Noonan syndrome or a related condition but with no detectable mutations in known Noonan-related genes. Clinical manifestations in the RIT1-mutation-positive individuals are consistent with those of Noonan syndrome, which is characterized by distinctive facial features, short stature, and congenital heart defects. Seventy percent of mutation-positive individuals presented with hypertrophic cardiomyopathy; this frequency is high relative to the overall 20% incidence in individuals with Noonan syndrome. Luciferase assays in NIH 3T3 cells showed that five RIT1 alterations identified in children with Noonan syndrome enhanced ELK1 transactivation. The introduction of mRNAs of mutant RIT1 into 1-cell-stage zebrafish embryos was found to result in a significant increase of embryos with craniofacial abnormalities, incomplete looping, a hypoplastic chamber in the heart, and an elongated yolk sac. These results demonstrate that gain-of-function mutations in RIT1 cause Noonan syndrome and show a similar biological effect to mutations in other RASopathy-related genes.

SAMD9 mutations cause a novel multisystem disorder, MIRAGE syndrome, and are associated with loss of chromosome 7

Adrenal hypoplasia is a rare, life-threatening congenital disorder. Here we define a new form of syndromic adrenal hypoplasia, which we propose to term MIRAGE (myelodysplasia, infection, restriction of growth, adrenal hypoplasia, genital phenotypes, and enteropathy) syndrome. By exome sequencing and follow-up studies, we identified 11 patients with adrenal hypoplasia and common extra-adrenal features harboring mutations in SAMD9. Expression of the wild-type SAMD9 protein, a facilitator of endosome fusion, caused mild growth restriction in cultured cells, whereas expression of mutants caused profound growth inhibition. Patient-derived fibroblasts had restricted growth, decreased plasma membrane EGFR expression, increased size of early endosomes, and intracellular accumulation of giant vesicles carrying a late endosome marker. Of interest, two patients developed myelodysplasitc syndrome (MDS) that was accompanied by loss of the chromosome 7 carrying the SAMD9 mutation. Considering the potent growth-restricting activity of the SAMD9 mutants, the loss of chromosome 7 presumably occurred as an adaptation to the growth-restricting condition.

Plasma angiotensin II concentrations in the early neonatal period

Background: There have been only a few reports on the renin-angiotensin system in low birthweight infants; in particular, plasma angiotensin II concentrations have not been studied. Aim: To investigate plasma angiotensin II concentrations in early neonatal infants including low birthweight infants. Methods: Forty six patients were studied, of whom 14 weighed not less than 2500 g (normal birth weight), 16 weighed less than 2500 g but not less than 1500 g (moderately low birth weight), and 16 weighed less than 1500 g (very low birth weight). Blood samples were collected twice, on day 0 and day 7. Angiotensin II concentration was assayed using an enzyme immunoassay kit with a microplate. Results: Geometric means of angiotensin II concentrations on day 7 were 19 pg/ml in the normal birthweight group, 28 pg/ml in the moderately low birthweight group, and 76 pg/ml in the very low birthweight group. The concentrations on day 7 in the very low birthweight group were significantly higher than those in the normal birthweight and moderately low birthweight groups (p  =  0.005, p  =  0.031). There were significant correlations between angiotensin II concentration on day 7 and gestational age (rs  =  −0.4, p  =  0.007) and birth weight (rs  =  −0.36, p  =  0.016). Conclusions: Specific physiological conditions associated with a very low birth weight are thought to be responsible for the increased concentration of angiotensin II on day 7. It is necessary to measure angiotensin II concentration for a longer period after birth and study the factors that could influence it.

Correlation between echocardiographic superior vena cava flow and short-term outcome in infants with asphyxia

OBJECTIVES To assess the relationship between superior vena cava (SVC) flow and short-term outcome in infants with perinatal asphyxia. METHODS Infants in sequence born after more than 35 weeks of gestation who had been hospitalized at the NICU and normal neonatal wards of Wakayama Medical University between May 2005 and September 2010 were recruited for this observational cohort study. The study eligibility criterion was the presence of perinatal asphyxia, as evidenced by abnormal fetal heart rate monitoring and an Apgar score of 7 or less at 1 min or need for resuscitation using positive pressure ventilation. SVC flow was measured in the first three days of life by Doppler echocardiography as described by Kluckow and Evans. Short-term outcome was defined as poor if MRI demonstrated bilateral lesions of the basal ganglia and thalamus and/or multicystic encephalomalacia due to hypoxic ischemia. RESULTS In the head cooling group, SVC flow in infants with a good outcome was lower than that in infants with a poor outcome at 12h (36.9±7.7 vs. 113.4±42.4 ml/kg/min (p=0.01)), 24h (75.2±25.3 vs. 155.6±45.7 ml/kg/min (p=0.03)), and 48 h (92.5±34.2 vs. 161.1±46.7 ml/kg/min (p=0.04)) after birth. SVC flow decreased promptly after introduction of head cooling in infants who had a good outcome, whereas it increased gradually after head cooling in those who had a poor outcome. CONCLUSION We speculate that regulation of brain circulation is disrupted in infants with asphyxia who show a poor outcome.

Acute fatty liver of pregnancy associated with fetal mitochondrial trifunctional protein deficiency.

Acute fatty liver of pregnancy (AFLP) is a devastating disorder of the maternal liver in the third trimester. Recent studies have demonstrated an association between AFLP and fetal fatty acid oxidation disorders. Here, we report a case of AFLP caused by fetal mitochondrial trifunctional protein (TFP) deficiency. A 21‐year‐old parous woman presented with nausea, genital bleeding and abdominal pain at 33 weeks of gestation. Laboratory data revealed hepatic failure and disseminated intravascular coagulopathy. The patient underwent emergency cesarean section and was diagnosed with AFLP from the clinical characteristics. She was successfully treated with frequent plasma exchange. The newborn presented severe heart failure and died on the 39th day after birth. Tandem mass spectrometry indicated long‐chain fatty acid oxidation disorder. Gene analysis demonstrated homozygous mutation in exon 13 of HADHB, the gene responsible for mitochondrial TFP deficiency. The parents carried a heterozygous mutation at the same location in HADHB.

Adverse perinatal and neonatal outcomes in patients with chronic abruption–oligohydramnios sequence

Chronic abruption–oligohydramnios sequence (CAOS) is a clinical condition with lasting vaginal bleeding and oligohydramnios because of chronic placental abruption, which seems to cause preterm labor and neonatal chronic lung disease (CLD). This prompted us to explore the correlation between perinatal/neonatal outcomes and CAOS.

Changes in Maternal and Child Health Outcomes After Introduction of a Helicopter into Perinatal Transportation in Japan

To examine the effect of perinatal helicopter transportation on maternal and child health. Helicopter transportation for the sparsely populated southern areas of Wakayama and Mie prefectures was introduced in June 2003. Maternal and child health statistics for 2000–2002 and 2004–2006 were compared between the south and north regions of the prefectures. There were 9 maternal transports from south Wakayama, 2 from north Wakayama, and 5 from south Mie in 2004–2006; and 13 neonatal transports from south Wakayama and 7 from north Wakayama during the same period. Decreases in neonatal and perinatal mortalities in 2004–2006 compared to 2000–2002 were greater in south Wakayama than in north Wakayama (−0.31 vs. −0.28, and −0.57 vs. −0.18, respectively); and greater in south Mie than in north Mie (−0.90 vs. −0.49, and −2.49 vs. −1.48, respectively). The changes in the number of maternal deaths between 2000–2002 and 2004–2006 were 0 in south Wakayama, 1 in north Wakayama, −2 in south Mie, and −1 in north Mie, with the greatest change occurring in south Mie. Use of a helicopter for perinatal transportation can possibly improve maternal and child health in sparsely populated areas far away from urban areas.

Neonatal tracheobiliary fistula diagnosed by MR cholangiopancreatography.

370 via a transverse upper abdominal incision. The esophageal hiatus was expanded and the remnant of the sac was mobilized from the FIGURE 1. Abdominal computed tomography image at a level below the diaphragm shows pneumobilia (arrows) and C ongenital bronchobiliary fistula, an uncommon malformation of the digestive tract, was first reported by Neuhauser et al (1) in 1952. The patient age distribution in previous case reports has ranged widely from infants to adults, despite the congenital nature of the anomaly. Here we report a Japanese neonatal case of tracheobiliary fistula that was diagnosed by bronchoscopy and magnetic resonance cholangiopancreatography.

Cytotoxic T-Lymphocyte-Associated Antigen 4 Gene Polymorphisms in Japanese Children with Infection-Associated Hemophagocytic Lymphohistiocytosis

Objective: This study examined whether genetic polymorphisms in cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), a negative regulator of T cells, are associated with infection-associated hemophagocytic lymphohistiocytosis (IHLH) in Japanese children. Methods: We investigated the alleles of four polymorphisms in the CTLA-4 gene [–318CT, +49AG, CT60 and a dinucleotide repeat length polymorphism (AT)n] in 43 Japanese children with IHLH and 100 healthy Japanese controls. The hyper-polymorphic (AT)n alleles were divided into two types; the shortest allele (designated as AT7) and the longer alleles (designated as AT>7). Results: A significant difference in the distribution of the (AT)n genotype was found between patients and controls (p = 0.028). Also, the frequency of the AT>7 allele was significantly higher in the patients with IHLH than in the controls (p = 0.007). No significant linkage disequilibrium was found between each polymorphism. With regard to laboratory data, patients homozygous for the CTLA-4 AT>7 allele showed significantly higher serum levels of lactate dehydrogenase and soluble interleukin-2 receptor than patients with the other alleles. Conclusion: These results suggest that CTLA-4 polymorphisms might play a role in the development of IHLH in Japanese children.

Wakayama Medical University Hospital perinatal helicopter ambulance service: 14 year review

In 2003, a perinatal helicopter air ambulance service was introduced for remote areas of Wakayama and Mie prefectures, Japan, but its long‐term impact on perinatal medicine has not yet been analyzed.