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Gitelman syndrome (GS) is an autosomal recessive disorder characterized by alkalosis, hypokalemia, and hypomagnesemia. Although hundreds of genetic variants associated with GS have been reported, many of them are categorized as of uncertain significance in ClinVar. Here, we describe a pediatric GS patient from a three-generation family whose mother and maternal grandmother were asymptomatic. The proband was a 16-year-old Japanese girl with muscle weakness and continuous hypokalemic metabolic alkalosis. The patient, her mother, and her maternal grandmother were compound heterozygous for, and each expressing a different combination of, previously reported SLC12A3variants in GS patients. The mother and the maternal grandmother had no symptoms related to GS, and blood gas tests showed that the blood potassium levels and venous pH were within normal limits; however, the venous blood HCO3- levels were slightly elevated. The phenotypic effect of missense mutations is difficult to evaluate, and accumulation of genotypic data with accurate phenotyping, including those of “healthy” and “asymptomatic” individuals in various ethnic populations, will improve the genetic diagnosis of GS.

A number of cases have been reported in recent years regarding the use of proton beam therapy to mitigate adverse events affecting important cranial organs in cases of rhabdomyosarcoma at parameningeal sites. However, few reports have described the use of proton beam therapy as urgent radiotherapy for parameningeal rhabdomyosarcoma with intracranial extension. We treated 3 patients diagnosed with parameningeal rhabdomyosarcoma extending into the cranium who were assessed at other hospitals as suitable for urgent radiotherapy and transferred to our hospital for proton beam therapy. These patients comprised 2 boys and 1 girl 6 to 12 years of age at diagnosis, and proton beam therapy was started on days 5, 11, and 23 after diagnosis, respectively. Patients with parameningeal rhabdomyosarcoma extending into the cranium can be transferred to institutions equipped to perform proton beam therapy. To minimize the interval to starting therapy, medical information should be shared with institutions capable of providing such therapy as soon as the possibility of intracranial soft-tissue sarcoma is recognized. Proton beam therapy is 1 option for radiotherapy in cases of intracranial rhabdomyosarcoma.

Background: Rhabdomyosarcoma (RMS) is one of the most common soft tissue sarcomas in children. Germline mutations in cancer predisposition genes have been detected in approximately 10% of pediatric cancers. However, the genetic background of RMS is still unclear, especially in Asian children. Procedure: DNA was extracted from the peripheral blood of children with RMS and cancer-associated genes analyzed using targeted re-sequencing. Results: Twenty patients participated in this study. The median age at diagnosis was 5.0 years. The male-to-female ratio was 3:2. There were three deaths due to RMS. One patient developed a second neoplasm. Nine patients had long-term co-morbidities. Five pathogenic variants were found in four patients: one nonsense variant of DICER1, one exon deletion of TP53, and three missense variants of LIG4 and MEN1. Two of the four patients had a family history of cancer. Two patients with missense variants of LIG4 had long-term co-morbidities of drug-induced cardiomyopathy. This is the first report of germline cancer-related gene variants with detailed clinical information in Japanese children with RMS. The missense variants of LIG4, essential for DNA double-strand break repair, were detected in two unrelated patients. Conclusions: When this is the first report of the germline genetic analysis of Japanese children with RMS, the frequency of the variant was almost equivalent to that of previous reports from Western countries. Unbiased exon sequencing may be useful to clarify the pathogenesis of RMS in children and in predicting the clinical course of these patients.