Biallelic CC2D2A variants, SNV and LINE-1 insertion simultaneously identified in siblings using long-read whole-genome sequencing and haplotype phasing.

Joubert syndrome (JBTS) is characterized by a magnetic resonance imaging appearance called 'molar tooth sign', neonatal breathing dysregulation and hypotonia, and developmental delay. Whole-exome analysis based on short-read sequencing has often contributed to the identification of causative single-nucleotide variants in patients clinically diagnosed with JBTS. However, ~10% of them are still undiagnosed even though a single possible pathogenic variant has been identified. We report a successful identification of biallelic variants using long-read whole-genome sequencing and haplotype phasing analysis in a family with two Japanese siblings having morphological brain abnormalities. The affected siblings had a novel nonsynonymous variant (CC2D2A:NM_001080522.2:c.4454A>G:p.(Tyr1485Cys)) and an exonic insertion of Long INterspercsed Element-1 (LINE-1). The allelicity of these variants was clearly proven without the data of parents. Finally, our survey of in-house genome sequencing data indicates that there are rare carriers of CC2D2A related diseases, who harbour the exonic LINE-1 insertion in the CC2D2A gene.

Detailed analysis of 26 cases of 1q partial duplication/triplication syndrome.

Partial 1q trisomy syndrome is a rare disorder. Because unbalanced chromosomal translocations often occur with 1q trisomy, it is difficult to determine whether patient symptoms are related to 1q trisomy or other chromosomal abnormalities. The present study evaluated genotype-phenotype correlations of 26 cases diagnosed with 1q partial trisomy syndrome. DNA microarray was used to investigate the duplication/triplication region of 16 cases. Although there was no overlapping region common to all 26 cases, the 1q41-qter region was frequently involved. One case diagnosed as a pure interstitial trisomy of chromosome 1q by G-banded karyotype analysis was instead found to be a pure partial tetrasomy by CytoScan HD Array. In four 1q trisomy syndrome cases involving translocation, the translocated partner chromosome could not be detected by DNA microarray analyzes despite G-banded karyotype analysis, because there were a limited number of probes available for the partner region. DNA microarray and G-banded karyotyping techniques were therefore shown to be compensatory diagnostic tools that should be used by clinicians who suspect chromosomal abnormalities. It is important to continue recruiting affected patients and observe and monitor their symptoms to reveal genotype-phenotype correlations and to fully understand their prognosis and identify causal regions of symptoms.

De novo triplication of 11q12.3 in a patient with developmental delay and distinctive facial features.

BACKGROUND: Triplication is a rare chromosomal anomaly. We identified a de novo triplication of 11q12.3 in a patient with developmental delay, distinctive facial features, and others. In the present study, we discuss the mechanism of triplications that are not embedded within duplications and potential genes which may contribute to the phenotype. RESULTS: The identified triplication of 11q12.3 was 557 kb long and not embedded within the duplicated regions. The aberrant region was overlapped with the segment reported to be duplicated in 2 other patients. The common phenotypic features in the present patient and the previously reported patient were brain developmental delay, finger abnormalities (including arachnodactuly, camptodactyly, brachydactyly, clinodactyly, and broad thumbs), and preauricular pits. CONCLUSIONS: Triplications that are not embedded within duplicated regions are rare and sometimes observed as the consequence of non-allelic homologous recombination. The de novo triplication identified in the present study is novel and not embedded within the duplicated region. In the 11q12.3 region, many copy number variations were observed in the database. This may be the trigger of this rare triplication. Because the shortest region of overlap contained 2 candidate genes, STX5 and CHRM1, which show some relevance to neuronal functions, we believe that the genomic copy number gains of these genes may be responsible for the neurological features seen in these patients.

[Diagnosis of incomplete Kawasaki disease].

We defined incomplete Kawasaki disease (KD) as those having less than 5 principal symptoms of KD in this article. Japanese Nationwide KD surveys revealed that the prevalence of coronary artery lesion in incomplete KD is almost the same as that of complete KD. Thus, incomplete KD should not be equated with mild KD. However, there is no royal way to make the correct diagnosis of incomplete KD. We have to remind that incomplete KD is not uncommon (around 15%) and is not mild KD when we work-up patients with few principal symptoms of KD. We have to pay attention also to other significant symptoms or findings of the guideline, especially to the skin changes at the site of BCG inoculation.

Prevalence of coronary artery abnormality in incomplete Kawasaki disease.

BACKGROUND: The aim of the present study was to determine the prevalence of coronary artery abnormality (CAA) and other clinical features in patients with incomplete Kawasaki disease (iKD) using the data from the 17th Japanese nationwide survey of KD. METHODS: iKD was defined as the presence of four or fewer of the principal symptoms of the Japanese diagnostic guidelines, regardless of whether the patient had CAA. A total of 15,857 cases were analyzed. RESULTS: Among 15,857 cases, 83.9% of patients had five to six principal symptoms (complete KD: cKD), and 16.1% had iKD. The prevalence of CAA in cKD was 14.2%, and 18.4% in iKD. The prevalence of CAA in patients with four principal symptoms was 18.1%, which was higher than in cKD cases (14.2%). Although the reliability of the data has some limitations, the prevalence of CAA among patients with one to three symptoms was 19.3%. Among all CAA patients, 14% had four symptoms, and 6% had only one to three symptoms. CONCLUSION: Incomplete KD should not be equated with mild KD. Patients with four principal symptoms were comparable to cKD with respect to CAA occurrence. In patients with one to three symptoms also, especially in those under 1 year and older than 4 years of age, other significant symptoms and laboratory findings of the guidelines are very important in making a correct and early diagnosis of iKD so as to prevent CAA.