Cross-Disorder Analysis of Genic and Regulatory Copy Number Variations in Bipolar Disorder, Schizophrenia, and Autism Spectrum Disorder

BACKGROUND

We aimed to determine the similarities and differences in the roles of genic and regulatory copy number variations (CNVs) in bipolar disorder (BD), schizophrenia (SCZ), and autism spectrum disorder (ASD).

METHODS

Based on high-resolution CNV data from 8708 Japanese samples, we performed to our knowledge the largest cross-disorder analysis of genic and regulatory CNVs in BD, SCZ, and ASD.

RESULTS

In genic CNVs, we found an increased burden of smaller (<100 kb) exonic deletions in BD, which contrasted with the highest burden of larger (>500 kb) exonic CNVs in SCZ/ASD. Pathogenic CNVs linked to neurodevelopmental disorders were significantly associated with the risk for each disorder, but BD and SCZ/ASD differed in terms of the effect size (smaller in BD) and subtype distribution of CNVs linked to neurodevelopmental disorders. We identified 3 synaptic genes (DLG2, PCDH15, and ASTN2) as risk factors for BD. Whereas gene set analysis showed that BD-associated pathways were restricted to chromatin biology, SCZ and ASD involved more extensive and similar pathways. Nevertheless, a correlation analysis of gene set results indicated weak but significant pathway similarities between BD and SCZ or ASD (r = 0.25-0.31). In SCZ and ASD, but not BD, CNVs were significantly enriched in enhancers and promoters in brain tissue.

CONCLUSIONS

BD and SCZ/ASD differ in terms of CNV burden, characteristics of CNVs linked to neurodevelopmental disorders, and regulatory CNVs. On the other hand, they have shared molecular mechanisms, including chromatin biology. The BD risk genes identified here could provide insight into the pathogenesis of BD.

Contribution of copy number variations to the risk of severe eating disorders

AIM

Eating disorders (EDs) are complex, multifactorial psychiatric conditions. Previous studies identified pathogenic copy number variations associated with NDDs (NDD-CNVs) in ED patients. However, no statistical evidence for an association between NDD-CNVs and EDs has been demonstrated. Therefore, we examined whether NDD-CNVs confer risk for EDs.

METHODS

Using array comparative genomic hybridization (aCGH), we conducted a high-resolution CNV analysis of 71 severe female ED patients and 1045 female controls. According to the American College of Medical Genetics guidelines, we identified NDD-CNVs or pathogenic/likely pathogenic CNVs in NDD-linked loci. Gene set analysis was performed to examine the involvement of synaptic dysfunction in EDs. Clinical data were retrospectively examined for ED patients with NDD-CNVs.

RESULTS

Of the samples analyzed with aCGH, 70 severe ED patients (98.6%) and 1036 controls (99.1%) passed our quality control filtering. We obtained 189 and 2539 rare CNVs from patients and controls, respectively. NDD-CNVs were identified in 10.0% (7/70) of patients and 2.3% (24/1036) of controls. Statistical analysis revealed a significant association between NDD-CNVs and EDs (odds ratio = 4.69, P = 0.0023). NDD-CNVs in ED patients included 45,X and deletions at KATNAL2, DIP2A, PTPRT, RBFOX1, CNTN4, MACROD2, and FAM92B. Four of these genes were related to synaptic function. In gene set analysis, we observed a nominally significant enrichment of rare exonic CNVs in synaptic signaling in ED patients (odds ratio = 2.55, P = 0.0254).

CONCLUSION

Our study provides the first preliminary evidence that NDD-CNVs may confer risk for severe EDs. The pathophysiology may involve synaptic dysfunction.

Regional decrease in gray matter volume is related to body dissatisfaction in anorexia nervosa

Anorexia nervosa (AN) is a psychiatric disorder, in which the prognosis for some patients is poor. The etiology and effective treatments for AN have not been established. We examined morphometric changes in the brain of AN and clarified how the changes were associated with symptoms and pathophysiology. We enrolled 52 participants: 7 with the restrictive type of AN, 13 with the binge-eating/purging type, 3 with eating disorder not otherwise specified, and 29 healthy controls. Participants underwent T1-weighted MRI. Group differences between patients and controls in gray matter volume (GMV) were analyzed using voxel-based morphometry. Age and body mass index (BMI) were considered covariates. Correlations between regional GMVs and drive for thinness and body dissatisfaction were examined. Patients had decreased GMV in the superior/middle temporal gyrus (STG/MTG), pulvinar, and superior frontal gyrus after correction for age and BMI, and in the STG/MTG, middle frontal gyrus, and cingulate after correction for age. A correlational group difference was detected for body dissatisfaction and GMV in the STG. Our findings suggest that decreased GMV in the STG is related to body dissatisfaction that could come from impaired visuospatial perception, together with GMV decreases in several regions, which may be involved in development of AN.

Risk factors for elevated liver enzymes during refeeding of severely malnourished patients with eating disorders: a retrospective cohort study

BACKGROUND

There are few previous reports regarding the cause and evolution of liver injury in patients with anorexia nervosa (AN) during the refeeding process, and its management remains controversial. This study aimed to determine the risk factors for elevated liver enzymes during refeeding and their effect on the therapeutic process in severely malnourished patients with eating disorders.

METHODS

In a retrospective cohort study of 167 female inpatients in a single hospital from January 2004 to March 2015, 67 who had normal alanine aminotransferase (ALT) levels on admission were divided into two groups according to the presence or absence of elevated ALT levels during refeeding, and then compared.

RESULTS

The median age and body mass index (BMI) of the patients on admission were 22 [interquartile range (IQR), 16-33] years and 12.2 (IQR, 11.1-13.0) kg/m², respectively. Compared with their cohorts, significantly more patients in the early onset age group (<15 years old) had elevated ALT levels during refeeding (67% vs. 33%, p = 0.033), as did patients with longer median time to nadir BMI (3.0 vs. 0 days, p = 0.03). In addition, onset age [odds ratio (OR): 0.274; 95% confidence interval (CI): 0.077-0.981; p = 0.047] and time to nadir BMI (OR: 1.271; 95% CI: 1.035-1.56; p = 0.022) were significantly associated with the odds of elevated ALT levels during refeeding.

CONCLUSIONS

The results of this study suggest that early age at onset may be a potential risk factor for elevated ALT levels during refeeding in severely malnourished patients with eating disorders. Furthermore, elevated ALT levels during refeeding were significantly associated with delay in the start of weight gain. No significant relationship was found between the amount of initial prescribed calories and elevated ALT levels during refeeding. The median time to maximum ALT was 27 (IQR, 21-38) days after the refeeding process started.

Association of Beck Depression Inventory score and Temperament and Character Inventory-125 in patients with eating disorders and severe malnutrition

The authors investigated the association between personality and physical/mental status in malnourished patients with eating disorders. A total of 45 patients with anorexia nervosa, avoidant/restrictive food intake disorder, and other specified feeding or eating disorders were included and compared with 39 healthy controls. Personality characteristics and severity of depression were assessed using the Temperament and Character Inventory-125 and Beck's Depression Inventory. Depression correlated with harm avoidance and self-directedness in both cases and controls. Body mass index did not correlate with personality in either group. These findings should be verified by longitudinal studies with higher weight/weight recovered patients.

Social insecurity in relation to orbitofrontal activity in patients with eating disorders: a near-infrared spectroscopy study

BACKGROUND

Functional neuroimaging techniques are widely used to elucidate changes in brain activity, and various questionnaires are used to investigate psychopathological features in patients with eating disorders (ED). It is well known that social skills and interpersonal difficulties are strongly associated with the psychopathology of patients with ED. However, few studies have examined the association between brain activity and social relationships in patients with ED, particularly in patients with extremely low body weight.

METHODS

In this study, 22-channel near-infrared spectroscopy was used to quantify regional hemodynamic changes during a letter fluency task (LFT) in 20 female patients with ED with a mean body mass index of 14.0 kg/m(2) and 31 female controls (CTLs). Symptoms were assessed using the Eating Disorder Inventory-2 and Beck Depression Inventory. We hypothesized that frontal activity in patients with ED would be lower than in CTLs and would show different correlations with psychopathological features compared with CTLs.

RESULTS

The LFT performance and score on the social insecurity subscale of the Eating Disorder Inventory-2 were significantly higher in the ED group than in the CTL group. The mean change in oxygenated hemoglobin (oxy-Hb) in bilateral frontal regions during the LFT was significantly smaller in the ED group than in the CTL group. Social insecurity score was positively correlated with the concentration of oxy-Hb in the bilateral orbitofrontal cortex in the ED group but not in the CTL group.

CONCLUSIONS

These results suggest that activity of the orbitofrontal cortex is associated with social insecurity and disturbed in patients with ED. Therefore, disturbed orbitofrontal cortex activity may underlie the lack of insight and social isolation that is characteristic of patients with ED.

Screening for pyrimidine metabolism disorders using dried filter-paper urine samples: method development and a pilot study in Nagoya City, Japan

A screening system for pyrimidine metabolism disorders by measurement with high-performance liquid chromatography using dried filter-paper urine samples is presented. This system permits the simultaneous determination of dihydrouracil, uracil, orotic acid and pseudouridine. The coefficient of variations for the four compounds on the filter-paper urine samples were 0.010 approximately 0.069 and the recoveries were 98.5 approximately 107.1%. The detection limits of the four compounds were 2 approximately 20 micromol/liter. The correlation between the filter-paper urine samples and liquid urine samples was excellent (0.938-0.988). We supeculated that this method could be used to detect pyrimidine metabolism disorders, such as dihydropyrimidinuria, dihydropyrimidine dehydrogenase deficiency and hereditary orotic aciduria. As a pilot study, we have analyzed dried filter-paper urine samples from 34, 200 healthy Japanese, and found three cases of dihydropyrimidinuria without clinical symptoms.

Dihydropyrimidinase deficiency: structural organization, chromosomal localization, and mutation analysis of the human dihydropyrimidinase gene

Dihydropyrimidinase (DHP) deficiency (MIM 222748) is characterized by dihydropyrimidinuria and is associated with a variable clinical phenotype. This disease might be associated with a risk of 5-fluorouracil toxicity, although no cases have been reported. We present here both the molecular characterization of the human DHP gene and, for the first time, the mutations causing DHP deficiency. The human DHP gene spans >80 kb and consists of 10 exons. It has been assigned to 8q22, by FISH. We performed mutation analysis of genomic DNA in one symptomatic and five asymptomatic individuals presenting with dihydropyrimidinuria. We identified one frameshift mutation and five missense mutations. Two related Japanese adult subjects were homozygous for the Q334R substitution, whereas two other, unrelated Japanese infant subjects were heterozygous for the same mutation, but this mutation is not common in the Japanese population. A Caucasian pediatric patient exhibiting epileptic attacks, dysmorphic features, and severe developmental delay was homozygous for W360R. Using a eukaryotic expression system, we showed that all mutations reduced enzyme activity significantly, indicating that these are crucial DHP deficiency-causing mutations. There was no significant difference, in residual activity, between mutations observed in the symptomatic and those observed in the asymptomatic individuals.

Population and family studies of dihydropyrimidinuria: prevalence, inheritance mode, and risk of fluorouracil toxicity

To evaluate the prevalence of dihydropyrimidinuria (DHPuria), we analyzed urine samples from 21,200 healthy Japanese infants, and found two cases of DHPuria without clinical symptoms. Based on this result, we estimated the prevalence to be approximately 1/10,000 births in Japan. In addition, we analyzed pyrimidine catabolism on a previously reported family with an adult DHPuria case. We newly identified the sister of the propositus as the second case of DHPuria in this family, because she excreted large amounts of dihydrouracil and dihydrothymine. The parents and the child of the propositus showed slight increases of dihydrouracil and dihydrothymine. This is the first family with 2 cases of DHPuria, indicating that DHPuria is an inherited condition. To determine the inheritance of DHPuria in this family and to examine the risk of 5-fluorouracil (5-FU) toxicity, a uracil loading test was performed on the parents. Urinary dihydrouracil concentrations in the parents after the loading were several times higher than those in normal control persons, the finding being consistent with DHPuria heterozygotes. This, along with data on the propositus, his sister, and his child, indicates that DHPuria is an autosomal recessive condition. In addition, DHPuria homozygotes may have a high risk of 5-FU toxicity, while the risk is relatively low in heterozygotes.

Hereditary orotic aciduria heterozygotes accompanied with neurological symptoms

We report a family with hereditary orotic aciduria heterozygotes. A 3-year-old boy who had been diagnosed as having cerebral palsy and mental retardation presented himself with an increase in excretion of urinary orotic acid. Enzymatic studies revealed that the boy and his healthy mother were hereditary orotic aciduria heterozygote carriers. We can not prove that this pyrimidine disorder caused his neurological symptoms, but his pyrimidine nucleoside supply may have been insufficient in his neonatal period.

[Nested polymerase chain reaction for the diagnosis and follow-up of tuberculous meningitis: a case report]

We presented a case of tuberculous meningitis in which a nested polymerase chain reaction was useful for its rapid diagnosis and follow-up. A 5-month-old girl was hospitalized for gastrointestinal complaints of 4 days' duration. She initially had no meningeal signs, but showed a bulging of the anterior fontanel on the 10th day of her illness. Cerebrospinal fluid examination revealed a cell count of 886/3 microliters (80% lymphocytes), protein of 20 mg/dl, and glucose of 27 mg/dl. Tuberculous meningitis was suspected clinically and an antituberculous therapy was commenced on the 13th day. Although repeated attempts to culture Mycobacterium tuberculosis were negative, the DNA of the organism was detected sequentially from the cerebrospinal fluid of the 13th and 16th day by the method of a nested polymerase chain reaction. The final diagnosis of tuberculous meningitis was established on the basis of the positive results of the nested polymerase chain reaction, a positive tuberculin test, and typical cerebrospinal fluid findings. She recovered rapidly in response to the therapy and was discharged from the hospital without any neurological sequelae on the 89th day. The follow-up samples of the nested polymerase chain reaction resulted as negative after the 26th day of the illness.

[A case of massive hemorrhagic enteritis due to rotavirus]

We described a 8-month-old boy of massive hemorrhagic enteritis due to rotavirus complicated by shock. As far as we know, this case is the first patient who developed vascular collapse from the gastrointestinal tract bleeding by rotavirus infection. Clinicians should be alerted to the possibility of the occurrence of severe hemorrhagic enteritis as a life threatening complication in rotavirus induced enteritis.