Table 1 Clinical findings in challenge families

1

Centronuclear myopathy and bilateral sensorineural hearing loss

• 10-year-old male diagnosed with centronuclear myopathy at 13 months based on clinical exam and muscle biopsy findings

• Uses a G-tube for supplemental feeding

• Uses nighttime ventilation support

• Able to walk limited distances (up to four city blocks), to run and to climb stairs with use of a railing

• Bilateral mild low to mid-frequency hearing loss

• No contributory family history

2

Right-sided structural heart defects and conduction defects

• Multiple family members with a variety of right-sided cardiac defects ranging in severity

• Proband is a 5-year-old female with history of a right ventricle mass that resolved spontaneously, persistent right bundle branch block (RBBB) and slightly dilated ascending aorta

• Mother has the same condition, not requiring intervention

• Maternal uncle has a pacemaker for Type II AV block and a history of pulmonary stenosis

• Maternal aunt died in neonatal period due to cardiac defects

• Maternal first cousin died in neonatal period due to a complex congenital cardiac defects involving hypertrophied right ventricle, tricuspid valve atresia, and second degree heart block

3

Nemaline myopathy

• 7-year-old male diagnosed with nemaline myopathy at 7 months based on muscle biopsy findings and clinical exam

• Bilateral club feet, requiring casting

• Myopathic facies, decreased muscle bulk, diffuse hypotonia (axial > appendicular), decreased range of motion and mild finger contractures noted at 4.5 months

• G-tube placed at 23 months for supplemental feeding

• No ventilation support is needed

• Can sit unsupported, but uses a walker to aid in ambulation