Erythropoietin levels were determined in 50 Greek females: 20 beta-thalas-saemia (beta-thai) heterozygotes, 15 with a diagnosis of iron-deficiency anaemia and 15 normal controls. In beta-thai trait carriers, the erythropoietin levels were slightly higher than in normal controls (16.65 ± 4.43 vs. 12.84 ± 2.47 mU/ml); these levels were significantly lower than those in iron-deficient subjects with the same degree of anaemia (55.24 ± 31.35 mU/ml). In both groups, the erythropoietin levels are statistically correlated with the severity of anaemia (r = -0.537 p < 0.05 for iron deficiency; r = -0.610 p < 0.01 for beta-thai heterozygotes). In beta-thai heterozygotes, a close inverse correlation with red cell number and erythropoietin levels was also noted. It is suggested that microcytosis accompanying beta-thai trait constitutes an additional factor intervening in the regulation of erythropoiesis.

Mitochondrial myopathy is a severe metabolic myopathy related to nuclear or mitochondrial DNA dysfunction. We present a rare case of mitochondrial myopathy, presented with multiple episodes of proximal muscle weakness, lactic acidosis, and severe rhabdomyolysis (CPK 319,990 U/L, lactic acid 22.31 mmol/L, and GFR 3.82 mL/min/1.73m2). She was hospitalized in the pediatric intensive care unit due to acute kidney injury, elevated blood pressure, and deterioration of respiratory and cardiac function. Investigation for inherited metabolic disorders showed elevated levels of ammonia, lactic acid to pyruvic acid ratio, and urine ketone bodies. Exome sequencing detected a homozygous pathogenic variant in FDX2 (ENST00000541276:p.Met4Leu/c.10A > T) and a heterozygous variant of uncertain significance in MSTO1 (ENST00000538143:p.Leu137Pro/c.410 T > C). After Sanger sequencing, the p.Met4Leu pathogenic variant in FDX2 (ENST00000541276:p.Met4Leu/c.10A > T) was identified in a heterozygous state in both her parents and sister. Recently, pathogenic variants in the FDX2 gene have been associated with mitochondrial myopathy, lactic acidosis, optic atrophy, and leukoencephalopathy. Only four reports of FDX2‐related rhabdomyolysis have been described before, but none of the previous patients had hyperammonemia. This is a rare case of severe mitochondrial myopathy in a pediatric patient related to a pathogenic FDX2 variant, suggesting the need for genetic analysis of the FDX2 gene in cases of suspicion of mitochondrial myopathies.

Tissue Doppler Imaging and Speckle Tracking Echocardiography are newer echo-cardiographic modalities, that assess myocardial and valvular function in congenital and acquired heart diseases in childhood. In addition, cross-sectional imaging including Cardiac Magnetic Resonance (CMR) and Cardiac Computed Tomography has been widely used over the last decade in paediatric cardiology, in order to evaluate intra-cardiac and extra-cardiac anatomy. Cardiac Magnetic Resonance particularly allows detailed analysis of myocardial function, and shunt quantification and has applications even in fetal life. This mini-review summarizes the basic principles of the above-advanced modalities and highlights their main indications and clinical applications in childhood.