Constitutional mismatch repair-deficiency (CMMRD) syndrome, alternatively known as biallelic mismatch repair deficiency syndrome, occurs in subset of pediatric cancer patients, including those with primary brain tumors.Patients from Arab and other developing countries are predicted to have higher incidence of CMMRD due to high prevalence of consanguinity.Integration of molecular and/or genomic testing into routine clinical care for pediatric cancer patients is important to identify patients with CMMRD syndrome.Patient with CMMRD-associated cancers may show increased responsiveness to immune checkpoint inhibitors.To the authors' knowledge, this is the first report in the Arab world of a durable response to immune checkpoint inhibitors in a pediatric glioblastoma patient.

BackgroundThe authors review the role of selenium and highlight possible low selenium levels in soil that may result in deficient states in Saudi Arabia.Case presentationThe authors report a case of selenium-responsive cardiomyopathy in a 15-month old Saudi Arabian boy. This case of selenium deficiency causing dilated cardiomyopathy is presented with failure to thrive, prolonged fever and respiratory distress. The investigations revealed selenium deficiency. Selenium supplementation along with anti-failure therapy [Furosimide, Captopril] was administered for 6 months. Following therapy the cardiac function, hair, skin and the general health of the patient improved significantly.ConclusionThe patient with dilated cardiomyopathy of unknown etiology, not responding to usual medication may be deficient in selenium. Serum selenium measurements should be included in the diagnostic work-up to ensure early detection and treatment of the disease. The selenium level in the Saudi population needs be determined. Vulnerable populations have to undergo regular selenium measurements and supplementation if indicated. Dependence on processed foods suggests that the Saudi population fortify themselves with nutrient and micronutrient supplements in accordance to the RDA.