Nemaline myopathy with severe congenital manifestation

Case presentation: Full-term newborn with reduced fetal movements during pregnancy, elective cesarean section, first child of a non-consanguineous couple with no family history of neurological disease. Apgar 5–5, severe respiratory distress, cyanosis and cardiorespiratory arrest. He required cardiopulmonary resuscitation and mechanical ventilation, persisting with hypotonia. On examination, facial hypomimia and carp mouth with jaw drop, severe hypotonia, immobile in bed, weak and exhaustible deep tendon reflexes, absence of sucking reflex and other primitive reflexes. Proximal strength of limbs 1+ and distal 2+. Arthrogryposis, myokymia and tongue fasciculation absent. The exams showed normal CPK, mild asymmetric dilatation of the lateral ventricles on MRI of the brain, echocardiogram with moderate functional tricuspid regurgitation with slight increase in pulmonary pressure, patent ductus arteriosus with left-right flow, and patent foramen ovale. The initial hypotheses were: SMA type 0, congenital myasthenia and congenital myopathy. The neuromuscular diseases panel showed a heterozygous pathogenic mutation in the ACTA1 gene that is associated with nemaline myopathy with autosomal recessive or dominant inheritance. This congenital myopathy has no curative treatment so far. The patient was discharged home with supportive care.

Discussion: Nemaline myopathy is a disease with variable phenotype whose most common expression is bulbar muscular weakness and congenital severe peripheral weakness. Of the 12 genes associated with the disease, the most frequently involved are NEB and ACTA1. Diagnosis depends on molecular testing or biopsy with electron microscopy and immunohistochemistry. Severe early-onset cases are associated with poor prognosis and high mortality.

Final comments: The severe hypotonic baby is a great challenge in the delivery room, thinking about neuromuscular causes enables a more aggressive approach and delivery in a specialized center. The diagnosis depends on expensive and difficult-to-access techniques in Brazil, however, it allows for notions of prognosis and establishment of the risk of recurrence.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
18 September 2023