Comprehensive genetic analysis confers high diagnostic yield in 16 Japanese patients with corpus callosum anomalies.

Corpus callosum anomalies (CCA) is a common congenital brain anomaly with various etiologies. Although one of the most important etiologies is genetic factors, the genetic background of CCA is heterogenous and diverse types of variants are likely to be causative. In this study, we analyzed 16 Japanese patients with corpus callosum anomalies to delineate clinical features and the genetic background of CCAs. We observed the common phenotypes accompanied by CCAs: intellectual disability (100%), motor developmental delay (93.8%), seizures (60%), and facial dysmorphisms (50%). Brain magnetic resonance imaging showed colpocephaly (enlarged posterior horn of the lateral ventricles, 84.6%) and enlarged supracerebellar cistern (41.7%). Whole exome sequencing revealed genetic alterations in 9 of the 16 patients (56.3%), including 8 de novo alterations (2 copy number variants and variants in ARID1B, CDK8, HIVEP2, and TCF4) and a recessive variant of TBCK. De novo ARID1B variants were identified in three unrelated individuals, suggesting that ARID1B variants are major genetic causes of CCAs. A de novo TCF4 variant and somatic mosaic deletion at 18q21.31-qter encompassing TCF4 suggest an association of TCF4 abnormalities with CCAs. This study, which analyzes CCA patients usung whole exome sequencing, demonstrates that comprehensive genetic analysis would be useful for investigating various causal variants of CCAs.

Renal function in angiotensinogen gene-mutated renal tubular dysgenesis with glomerular cysts.

BACKGROUND: Inherited renal tubular dysgenesis (RTD) is caused by mutations in the genes encoding the components of the renin-angiotensin system (RAS). RTD is characterized by oligohydramnios, renal failure, neonatal hypocalvaria, and severe hypotension. The histological characteristics, underlying mechanism, and long-term prognosis remain poorly known. CASE-DIAGNOSIS/TREATMENT: We describe here a 4-year-old female with RTD. Endocrinologic analysis showed a discrepancy between low plasma renin activity and high active renin concentration, suggesting a loss of the renin substrate, angiotensinogen (AGT). Direct sequencing revealed a frameshift deletion at nucleotide 1,355 in exon 5 in the AGT gene. Although a histological hallmark is regarded to be the absence or poor development of the proximal tubule, the patient does have minimally impaired function of the proximal tubule. Glomerular cysts without glomerular tufts were noted in approximately half of the glomeruli. The urinary concentrating ability and sodium reabsorption and potassium excretion in the distal nephron were severely affected. CONCLUSIONS: The patient has an impaired function of the distal nephron despite minimally affected function of the proximal tubule, probably attributed to renal tubular dysgenesis and fetal hypoperfusion. The renal tubular maturity and the severity of ischemic injury may be key determinants of the clinical symptoms and pathological findings in RTD, in which the RAS plays an important role.

Clinical variations of epileptic syndrome associated with PACS2 variant.

BACKGROUND: Recent studies have suggested that two PACS2 pathogenic variants, c.625G > A (p.Glu209Lys) and c.631G > A (p.Glu211Lys), have been causally linked to the characteristic developmental and epileptic encephalopathy, including autistic behaviors, hypotonia, cerebellar dysgenesis and facial dysmorphism. Their seizures appear most difficult to control in neonatal and infant period, but improve after the first year of life. We herein report three patients with the same PACS2 variant, c.625G > A (p.Glu209Lys), showing different characteristics from previous reports. CASE REPORT: Case 1, a 2-year-old girl, developed frequent tonic convulsions 2 weeks after birth. Brain magnetic resonance imaging showed a decrease in posterior periventricular white matter volume, an enlargement of the inferior horn of lateral ventricles and old subependymal hemorrhage. Epilepsy is now controlled with antiepileptic drugs. Case 2, a 12-year-old girl, developed generalized tonic convulsions 3 days after birth. Although epilepsy had been controlled since the age of 4, she developed Lennox-Gastaut syndrome at 9 years old. Case 3, a 3-year-old girl, developed tonic convulsions 3 days after birth. She now exhibits normal psychomotor development, and epilepsy is controlled without medicine. CONCLUSION: PACS2-related epileptic syndrome presents variable phenotypes than previously reported. We think that our findings expand the clinical spectrum of this disease, and provide important information about the differential diagnosis of neonatal-onset epileptic syndrome.

Clinical and genetic characteristics of patients with Doose syndrome.

OBJECTIVE: To elucidate the genetic background and genotype-phenotype correlations for epilepsy with myoclonic-atonic seizures, also known as myoclonic-astatic epilepsy (MAE) or Doose syndrome. METHODS: We collected clinical information and blood samples from 29 patients with MAE. We performed whole-exome sequencing for all except one MAE case in whom custom capture sequencing identified a variant. RESULTS: We newly identified four variants: SLC6A1 and HNRNPU missense variants and microdeletions at 2q24.2 involving SCN1A and Xp22.31 involving STS. Febrile seizures preceded epileptic or afebrile seizures in four patients, of which two patients had gene variants. Myoclonic-atonic seizures occurred at onset in four patients, of which two had variants, and during the course of disease in three patients. Variants were more commonly identified in patients with a developmental delay or intellectual disability (DD/ID), but genetic status was not associated with the severity of DD/ID. Attention-deficit/hyperactivity disorder and autistic spectrum disorder were less frequently observed in patients with variants than in those with unknown etiology. SIGNIFICANCE: MAE patients had genetic heterogeneity, and HNRNPU and STS emerged as possible candidate causative genes. Febrile seizures prior to epileptic seizures and myoclonic-atonic seizure at onset indicate a genetic predisposition to MAE. Comorbid conditions were not related to genetic predisposition to MAE.