Kei Ohashi

Novel splicing mutation in the ASXL3 gene causing Bainbridge-Ropers syndrome

Bainbridge–Ropers syndrome (BRPS) is characterized by severe developmental delay, feeding problems, short stature, characteristic facal appearance including arched eyebrows and anteverted nares, and ulnar deviation of the hands. BRPS is caused by a heterozygous mutation in the additional sex combs‐like 3 (ASXL3) gene. We describe a patient with severe developmental delay, feeding problems, short stature, autism, and sleep disturbance with a heterozygous de novo splicing mutation in the ASXL3 gene. Reported disease‐causing mutations in ASXL3 are located mostly in the first half of exon 11, analogous to ASXL1 mutations of which result in Bohring–Opitz syndrome (BOS). Our findings suggest that the expression of the truncated ASXL3 protein, including ASXN and ASXH domains, give rise to BRPS, which is distinct from but overlaps with BOS.

A combination of genetic and biochemical analyses for the diagnosis of PI3K-AKT-mTOR pathway-associated megalencephaly

BackgroundConstitutive activation of the PI3K-AKT-mTOR pathway (mTOR pathway) underlies megalencephaly in many patients. Yet, prevalence of the involvement of the PI3K-AKT-mTOR pathway in patients with megalencephaly remains to be elucidated, and molecular diagnosis is challenging. Here, we have successfully established a combination of genetic and biochemical methods for diagnosis of mTOR pathway-associated megalencephaly, and have attempted to delineate the clinical characteristics of the disorder.MethodsThirteen patients with an increased head circumference and neurological symptoms participated in the study. To evaluate the activation of the mTOR pathway, we performed western blot analysis to determine the expression levels of phosphorylated S6 ribosomal protein (phospho-S6 protein) in lymphoblastoid cell lines from 12 patients. Multiplex targeted sequencing analysis for 15 genes involved in the mTOR pathway was performed on 12 patients, and whole-exome sequencing was performed on one additional patient. Clinical features and MRI findings were also investigated.ResultsWe identified pathogenic mutations in six (AKT3, 1 patient; PIK3R2, 2 patients; PTEN, 3 patients) of the 13 patients. Increased expression of phospho-S6 protein was demonstrated in all five mutation-positive patients in whom western blotting was performed, as well as in three mutation-negative patients. Developmental delay, dysmorphic facial features were observed in almost all patients. Syndactyly/polydactyly and capillary malformations were not observed, even in patients with AKT3 or PIK3R2 mutations. There were no common phenotypes or MRI findings among these patients.ConclusionsA combination of genetic and biochemical methods successfully identified mTOR pathway involvement in nine of 13 (approximately 70%) patients with megalencephaly, indicating a major contribution of the pathway to the pathogenesis of megalencephaly. Our combined approach could be useful to identify patients who are suitable for future clinical trials using an mTOR inhibitor.

Concordance of DSM‐5 and DSM‐IV‐TR classifications for autism spectrum disorder

The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM‐5) was published in May 2013. Autism spectrum disorder (ASD) has been structured for the three subtypes of pervasive developmental disorder (PDD), but the number of impairment in social and communication dimension is not stated.

Application of the Final DSM-5 Criteria for Young Children with Autism Spectrum Disorder

Background: DSM-5 has received considerable attention all over the world. This study aimed to compare the diagnostic outcomes using both DSM--TR and the final version of DSM-5. Methods: One hundred eighty children under 5 years old at risk for neurodevelopmental disorders had been detected by a regional screening system in Nagoya, Japan. We collected their information from diagnostic records including scores of the Pervasive Developmental Disorders Autism Society Japan Rating Scale. Results: All 8 cases with autistic disorder and all 27 with Aspergers disorder corresponded to the ASD criterion. Although 2 cases with PDD-NOS were suspected of social communication disorder, 27 cases with PDD-NOS corresponded to ASD. Among 47 cases with specific language impairment, 5 cases were suspected of social communication disorder. Conclusion: Most of the cases (62/64) with PDDs met the ASD criterion, but the abolition of subcategories of PDDs results in one criteria of ASD covering a wide range, from extremely severe to more mild types. Further investigation and discussion are necessary for an appropriate use of DSM-5.

CTCF deletion syndrome: clinical features and epigenetic delineation

Background Heterozygous mutations in CTCF have been reported in patients with distinct clinical features including intellectual disability. However, the precise pathomechanism underlying the phenotype remains to be uncovered, partly because of the diverse function of CTCF. Here we describe extensive clinical and genetic investigation for two patients with a microdeletion encompassing CTCF. Methods We performed genetic examination including comprehensive investigation of X chromosome inactivation and DNA methylation profiling at imprinted loci and genome-wide. Results Two patients showed comparable clinical features to those in a previous report, indicating that haploinsufficiency of CTCF was the major determinant of the microdeletion syndrome. Despite the haploinsufficiency of CTCF, X chromosome inactivation was normal. DNA methylation at imprinted loci was normal, but hypermethylation at CTCF binding sites was demonstrated, of which PRKCZ and FGFR2 were identified as candidate genes. Conclusions This study confirms that haploinsufficiency of CTCF causes distinct clinical features, and that a microdeletion encompassing CTCF could cause a recognisable CTCF deletion syndrome. Perturbed DNA methylation at CTCF binding sites, not at imprinted loci, may underlie the pathomechanism of the syndrome.

A novel missense mutation in the HECT domain of NEDD4L identified in a girl with periventricular nodular heterotopia, polymicrogyria and cleft palate

We identified a novel de novo heterozygous missense mutation in the NEDD4L gene (NM_015277: c.2617G>A; p.Glu873Lys) through whole-exome sequencing in a 3-year-old girl showing severe global developmental delay, infantile spasms, cleft palate, periventricular nodular heterotopia and polymicrogyria. Mutations in the HECT domain of NEDD4L have been reported in patients with a neurodevelopmental disorder along with similar brain malformations. All patients reported with NEDD4L HECT domain mutations showed periventricular nodular heterotopia, and most had seizures, cortex anomalies, cleft palate and syndactyly. The unique constellation of clinical features in patients with NEDD4L mutations might help clinically distinguish them from patients with other genetic mutations including FLNA, which is a well-known causative gene of periventricular nodular heterotopia. Although mutations in the HECT domain of NEDD4L that lead to AKT-mTOR pathway deregulation in forced expression system were reported, our western blot analysis did not show an increased level of AKT-mTOR activity in lymphoblastoid cell lines (LCLs) derived from the patient. In contrast to the forced overexpression system, AKT-mTOR pathway deregulation in LCLs derived from our patient seems to be subtle.

Combined genetic analyses can achieve efficient diagnostic yields for subjects with Alagille syndrome and incomplete Alagille syndrome

We evaluated combined genetic analyses with targeted next‐generation sequencing (NGS), multiplex ligation probe amplification (MLPA) of Jagged1 (JAG1) genes and microarray comparative genomic hybridisation (CGH) in subjects with Alagille syndrome, incomplete clinical features of Alagille syndrome and biliary atresia.

Distinctive facies, macrocephaly, and developmental delay are signs of a PTEN mutation in childhood

BACKGROUND Germline mutations of the PTEN gene are responsible for several PTEN hamartoma tumor syndromes. They are also implicated as a cause of macrocephaly and mild to severe developmental delay, regardless of the presence or absence of hamartomas in childhood. Nevertheless, because of limited information, the clinical features present during childhood in patients with a PTEN mutation are yet to be elucidated. METHODS PTEN mutations were investigated by multiplex targeted sequencing of genomic DNA from 33 children with increased head circumference (>+2 SD) and developmental delay. The clinical features of all the patients with a PTEN mutation were abstracted by dysmorphologists. RESULTS We have identified six children with a PTEN mutation. Clinical dissection of these six patients, in addition to patient reports in the literature, revealed distinctive facial features that included frontal bossing, dolichocephaly, horizontal eyebrows, and a depressed nasal bridge. Macrocephaly (+3.2 to +6.0 SD) was noticeable compared to their height (-0.8 to +2.1 SD), and the difference in the SD value of head circumference and height was more than 3 SD in all patients. CONCLUSION The presence of distinctive facies, extreme macrocephaly with normal to mildly high stature, and developmental delay may be useful for identifying patients with a PTEN mutation in childhood. Early identification of patients with a PTEN mutation would help uncover the natural course of tumor development in this group of individuals who have a possible predisposition to cancer, and be important for the development of an optimal surveillance strategy.

Molecular genetic and clinical delineation of 22 patients with congenital hypogonadotropic hypogonadism.

Abstract Background: Congenital hypogonadotropic hypogonadism (CHH) is classified as Kallmann syndrome (KS) with anosmia/hyposmia or normosmic (n)CHH. Here, we investigated the genetic causes and phenotype-genotype correlations in Japanese patients with CHH. Methods: We enrolled 22 Japanese patients with CHH from 21 families (18 patients with KS and 4 with nCHH) and analyzed 27 genes implicated in CHH by next-generation and Sanger sequencing. Results: We detected 12 potentially pathogenic mutations in 11 families, with three having a mutation in ANOS1 (X-linked recessive); three and four having a mutation in FGFR1 and CHD7, respectively (autosomal dominant); and one having two TACR3 mutations (autosomal recessive). Among four patients with KS carrying a CHD7 mutation, one had perceptive deafness and two had a cleft lip/palate. Conclusions: The frequency of CHH genes in the Japanese was compatible with previous reports, except that CHD7 mutations might be more common. Furthermore, partial phenotype-genotype correlations were demonstrated in our cohort.

Viral Load Before and After Exchange Transfusion in a Neonate with Hyperbilirubinemia and Congenital Cytomegalovirus Infection

Introduction: Cytomegalovirus is the most common cause of intrauterine infection in developed countries. Between 10% and 15% of infants infected with congenital cytomegalovirus exhibits the clinically apparent or symptomatic form of the disease. Exchange transfusion is an established therapy for hyperbilirubinemia and severe anemia. However, to the best of our knowledge, the viral load of cytomegalovirus before and after exchange transfusion has not been previously reported. Case report: A Japanese female was delivered at 36 weeks of gestation to a 29-year-old gravida 3 para 3 by emergency Cesarean section because of non-reassuring fetal status. Hepatomegaly, splenomegaly, generalized petechiae, leptocephaly, and jaundice were noted at birth. On admission, her total bilirubin was 14.2 mg/dL, cytomegalovirus immunoglobulin M was positive (4.63 mg/dL), and her head ultrasound and computed tomography showed left intraventricular calcification and bilateral ventriculomegaly. Toxoplasma, rubella, and herpes simplex virus serologies were negative. The exchange transfusion was performed for the treatment of early onset hyperbilirubinemia, not for the treatment of congenital cytomegalovirus infection. The cytomegalovirus viral load before and after exchange transfusion was investigated by real-time polymerase chain reaction, and the plasma viral load of cytomegalovirus was not significantly decreased from before (8.7×105/mL) to after (4.3×105/mL) exchange transfusion. Conclusion: Exchange transfusion did not reduce the viral load of cytomegalovirus in severe congenital cytomegalovirus infection.