Duplications in the G3 domain or switch II region in HRAS identified in patients with Costello syndrome.

Costello syndrome (CS) is an autosomal-dominant disorder characterized by distinctive facial features, hypertrophic cardiomyopathy, skeletal abnormalities, intellectual disability, and predisposition to cancers. Germline variants in HRAS have been identified in patients with CS. Intragenic HRAS duplications have been reported in three patients with a milder phenotype of CS. In this study, we identified two known HRAS variants, p.(Glu63_Asp69dup), p.(Glu62_Arg68dup), and one novel HRAS variant, p.(Ile55_Asp57dup), in patients with CS, including a patient with craniosynostosis. These intragenic duplications are located in the G3 domain and the switch II region. Cells expressing cDNA with these three intragenic duplications showed an increase in ELK-1 transactivation. Injection of wild-type or mutant HRAS mRNAs with intragenic duplications in zebrafish embryos showed significant elongation of the yolk at 11 h postfertilization, which was improved by MEK inhibitor treatment, and a variety of developmental abnormalities at 3 days post fertilization was observed. These results indicate that small in-frame duplications affecting the G3 domain and switch II region of HRAS increase the activation of the ERK pathway, resulting in developmental abnormalities in zebrafish or patients with CS.

Case Report: Retroaortic Innominate Vein With Supracardiac Total Anomalous Pulmonary Venous Connection.

A retroaortic innominate vein (RAIV) is a rare anomaly that passes posterior to the ascending aorta to join the superior vena cava and is associated with congenital heart disease (CHD). The RAIV and normal left innominate vein (LIV) rarely duplicate. The etiology of the RAIV and its relationship with CHD remains unknown. We report a case involving a 1-month-old baby girl with RAIV and supracardiac total anomalous pulmonary venous connection (TAPVC). Transthoracic echocardiogram demonstrated a pulmonary venous confluence (CPV) posterior to the left atrium, an abnormal vertical vein (VV) that originated from the CPV, and a normally positioned LIV. Three-dimensional cardiac computed tomography revealed the VV and RAIV to which it merged. This is the first reported case of a combination of RAIV and isolated TAPVC. We speculate that the VV is connected to the CPV during fetal life, thus leaving the RAIV behind. The RAIV may be detected in various forms with the development of new diagnostic imaging methods. Although a RAIV itself does not require treatment, establishing a correct diagnosis before invasive tests and procedures are performed can help prevent unexpected complications.