We describe a case of a Japanese boy with syndromic congenital sideroblastic anemia who presented with various non-hematological symptoms. Genetic analysis showed a heterozygous frameshift mutation (c.1639delA) and T/T genotype of the common coding single nucleotide polymorphism rs10117 (c.1933C>T) in HSPA9. Parental analysis revealed that the father carried the same frameshift mutation as well as rs10117 (T/T) but was not anemic. While the rs10117T allele is associated with lower HSPA9 expression, the expression levels are variable. We speculate that the possible differences in the HSPA9 mRNA expression levels between the child and his father may have caused the phenotypic difference.

Thrombohemorrhagic disorders are the main cause of morbidities and mortalities of essential thrombocythemia (ET), which are typically observed at age 50–60 years and rarely encountered in adolescence or childhood. Recently, anagrelide, a quinazinolone derivative, has been used as a therapeutic agent for ET. Although it is used to reduce platelet count, its cardiotoxicity has been reported. Here, we present an 18-year-old boy with ET who was treated with anagrelide and developed acute myocardial infarction. This was presumed to be an effect of anagrelide administration and, specifically, damage to the coronary arterial endothelial cell exacerbated by ET.