Neonatal diagnosis of ACTA2-related disease: A case report and review of literature

Multisystemic smooth muscle dysfunction syndrome (MSMDS, OMIM # 613834) is a rare autosomal dominant condition caused by pathogenetic variants of ACTA2 gene that result in impaired muscle contraction. MSMDS is characterized by an increased susceptibility to aneurismal dilatations and dissections, patent ductus arteriosus, early onset coronary artery disease, congenital mydriasis, chronic interstitial lung disease, hypoperistalsis, hydrops of gall bladder, and hypotonic bladder. Here, we report an early diagnosis of a MSMDS related to ACTA2 p.Arg179His (R179H) mutation in a newborn and performed a review of the literature. An early diagnosis of MSMDS is extremely important, because of the severe involvement of cardiovascular system in the MSMDS. Multidisciplinary care and surveillance and timely management of symptoms are important to reduce the risk of complications.

Persistent anterior tunica vasculosa lentis in multisystemic smooth muscle dysfunction syndrome: A case report

RATIONALE

Multisystemic smooth muscle dysfunction syndrome (MSMDS) is a genetic disease that affects multiple organs. The report here concerns a patient with MSMDS, who is known so far as the youngest among all the reported patients. In addition to the typical manifestations, we observed previously unreported ocular abnormalities, including persistent anterior tunica vasculosa lentis (TVL) and early-onset retinal arteriolar tortuosity, by the fluorescein angiography (FA).

PATIENT CONCERNS

The patient was admitted to the neonatal intensive care unit immediately after birth for a diagnosis of urinary system dysplasia during fetal life. After a thorough examination, the patient was found with patent ductus arteriosus, pulmonary hypertension, cerebrovascular disease, hypotonic bladder, intestinal malrotation, and congenital mydriasis. The FA of the eyes undertaken in her 6-week demonstrated perfused vasculature in the persistent anterior TVL and prominent retinal arteriolar tortuosity. The whole exome sequencing revealed a de novo heterozygous ACTA2 gene missense mutation p.R179H.

DIAGNOSES

The patient was diagnosed with MSMDS.

INTERVENTIONS

Follow-up observation.

OUTCOMES

At the 3-month follow-up, no change of the ocular disease was observed.

LESSONS

The persistent anterior TVL in this case implies that ACTA2 p.R179H mutation affects not only the smooth muscle cells but also the pericytes, and further affects the TVL regression. The prominent retinal arteriolar tortuosity in this 6-week-old infant indicates that the retinal arteriolar tortuosity can present early in MSMDS.

Iris anomalies and the incidence of ACTA2 mutation

BACKGROUND

Central cysts of the iris pigment epithelium, or iris flocculi, are frequently reported in the literature in association with thoracic aortic aneurysm and dissection due to smooth muscle alpha-actin 2 (ACTA2) mutations. Children with ACTA2 mutations may also present with congenital mydriasis. We report our experience regarding the frequency of ACTA2 mutation in children with the above iris anomalies.

METHODS

This is a retrospective, consecutive case series of all children presenting for iris flocculi or congenital mydriasis at a single tertiary centre from October 2012 to December 2016.

RESULTS

13 children with iris flocculi and 3 with congenital mydriasis presented during the study period. 10 children with iris flocculi completed genetic testing, and none were positive for ACTA2 mutation. All children with congenital mydriasis presented with a multisystem smooth muscle dysfunction syndrome; two of these three children tested positive for missense R179 ACTA2 mutations.

CONCLUSIONS

In this series, ACTA2 mutation or copy number variation was not detected in children presenting for iris flocculi, whereas congenital mydriasis was associated with R179 mutation in both cases that tested positive for ACTA2 mutation. The case of congenital mydriasis without typical cardiac features of the R179 ACTA2 phenotype or intracranial vasculopathy was negative for ACTA2 mutation. While all children presenting with these iris anomalies should be offered a genetic evaluation, incidence data should inform genetic counselling, particularly in the absence of a family history of aneurysm or sudden death, or systemic signs of smooth muscle dysfunction.

Clinical history and management recommendations of the smooth muscle dysfunction syndrome due to ACTA2 arginine 179 alterations

PURPOSE

Smooth muscle dysfunction syndrome (SMDS) due to heterozygous ACTA2 arginine 179 alterations is characterized by patent ductus arteriosus, vasculopathy (aneurysm and occlusive lesions), pulmonary arterial hypertension, and other complications in smooth muscle-dependent organs. We sought to define the clinical history of SMDS to develop recommendations for evaluation and management.

METHODS

Medical records of 33 patients with SMDS (median age 12 years) were abstracted and analyzed.

RESULTS

All patients had congenital mydriasis and related pupillary abnormalities at birth and presented in infancy with a patent ductus arteriosus or aortopulmonary window. Patients had cerebrovascular disease characterized by small vessel disease (hyperintense periventricular white matter lesions; 95%), intracranial artery stenosis (77%), ischemic strokes (27%), and seizures (18%). Twelve (36%) patients had thoracic aortic aneurysm repair or dissection at median age of 14 years and aortic disease was fully penetrant by the age of 25 years. Three (9%) patients had axillary artery aneurysms complicated by thromboembolic episodes. Nine patients died between the ages of 0.5 and 32 years due to aortic, pulmonary, or stroke complications, or unknown causes.

CONCLUSION

Based on these data, recommendations are provided for the surveillance and management of SMDS to help prevent early-onset life-threatening complications.

Extracorporeal Life Support in Multisystem Smooth Muscle Dysfunction Syndrome

We describe an infant with congenital mydriasis, patent ductus arteriosus (PDA), pulmonary hypertension, and cystic lung disease. She had all the major components of multisystemic smooth muscle dysfunction syndrome. Due to progressive respiratory deterioration, she required surgical PDA interruption, extracorporeal life support, and subsequent prolonged respiratory support. Genetic testing revealed ACTA2 R179H mutation and cystic lung disease on biopsy.