Multisystem smooth muscle dysfunction syndrome in a Chinese girl: A case report and review of the literature

BACKGROUND: Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a rare genetic disease worldwide. The main mutation is the actin alpha 2 (ACTA2) gene p.R179H. In this paper, we report a Chinese MSMDS patient and systematically review the previous literature. CASE SUMMARY: Here, we report a 9.6-month-old Chinese girl who was diagnosed with MSMDS based on her history and symptoms, such as recurrent cough, wheezing, and complications with congenital fixed dilated pupils. Chest high-resolution computed tomography revealed inhomogeneous lung transparency, obvious exudative lesions, and some lung fissures that were markedly thickened. Cranial magnetic resonance imaging excluded bleeding and infarction but showed abnormal signals in the centrum ovale majus and bilateral periventricular regions. Echocardiography only showed patent foramen ovale, and no patent ductus arteriosus, pulmonary artery dilatation, or pulmonary hypertension was found. Bronchoscopy indicated moderate bronchial malacia. These examinations in conjunction with the typical eye abnormality suggested a diagnosis of MSMDS, and sequencing of exon 6 of the ACTA2 gene demonstrated the heterozygous mutation c.536G>A, p.R179H. However, her parents’ gene analyses were normal. CONCLUSION: MSMDS is a rare genetic disease mainly caused by the mutation of the ACTA2 gene p.R179H. Early genetic diagnosis should be performed for children presenting with congenital fixed dilated pupils and patent ductus arteriosus. During the process of diagnosis and treatment, clinicians should be on high alert for cerebrovascular, cardiovascular, and pulmonary complications.