Search

Abstract Background Autosomal recessive distal renal tubular acidosis (dRTA) is a rare hereditary disease caused by pathogenic variants in the ATP6V0A4 gene or ATP6V1B1 gene, and characterized by hyperchloremic metabolic acidosis with normal anion gap, hypokalemia, hypercalciuria, hypocitraturia and nephrocalcinosis. Although several intronic nucleotide variants in these genes have been detected, all of them fell in the apparent splice consensus sequence. In general, transcriptional analysis is necessary to determine the effect on function of the novel intronic variants located out of splicing consensus sequences. In recent years, functional splicing analysis using minigene construction was used to assess the pathogenicity of novel intoronic variant in various field. Methods We investigated a sporadic case of dRTA with a compound heterozygous mutation in the ATP6V0A4 gene, revealed by next generation sequencing. One variant was already reported as pathogenic; however, the other was a novel variant in intron 11 (c.1029 + 5G > A) falling outside of the apparent splicing consensus sequence. Expression of ATP6V0A4 was not detected in peripheral leukocytes by RT-PCR analysis. Therefore, an in vitro functional splicing study using minigene construction was conducted to analyze the splicing pattern of the novel variant. Results A minigene assay revealed that the novel intronic variant leads to a 104 bp insertion immediately following exon 11. In addition, this result was confirmed using RNA extracted from the patient’s cultured leukocytes. Conclusion These results proved the pathogenicity of a novel intronic variant in our patient. We concluded that the minigene assay is a useful, non-invasive method for functional splicing analysis of inherited kidney disease, even if standard transcriptional analysis could not detect abnormal mRNA.

Carcinoma ex pleomorphic adenoma (Ca ex PA) is a rare malignant tumor of salivary glands that originates in a primary (de novo) or recurrent pleomorphic adenoma. In the carcinoma component of Ca ex PA, many histological subtypes have been identified. It is difficult to make the diagnosis of this tumor because it has various histological findings. A case of Ca ex PA involving a very elderly woman's soft palate is reported. A 92-year-old woman visited our hospital with a chief complaint of a soft palatal mass. The mass was suspected to be a pleomorphic adenoma based on the clinical and magnetic resonance imaging findings. The tumor was diagnosed as Ca ex PA after the surgical procedure. The histological subtype of the malignant component was adenocarcinoma not otherwise specified (NOS). Although she had many indicators of a poor prognosis, no additional therapy was performed because of her age. It was reported that accurate diagnosis and surgical management of patients presenting with Ca ex PA could increase their survival rates. The management of Ca ex PA in very elderly people should be explored, taking into account their age, physical status, and risks.