9
Table 5. Clinical Features in Patients with HCM Phenocopies
(Mimics)
Typical
Presentation Age
Systemic
Features Possible Etiology
Diagnostic
Approach
Infants (0–12 mo)
and toddlers
Dysmorphic
features, failure to
thrive, metabolic
acidosis
• RASopathies
• Glycogen storage
diseases, other
metabolic or
mitochondrial
diseases
• Infant of a
mother with
diabetes
• Geneticist
assessment
• Newborn
metabolic
screening
• Specific
metabolic assays
• Genetic testing
Early childhood Delayed or
abnormal cognitive
development,
visual or hearing
impairment
• RASopathies
• Mitochondrial
diseases
• Biochemical
screening
• Genetic testing
Youth and
adolescence
Skeletal muscle
weakness or
movement disorder
• Friedrich's ataxia
• Danon disease
• Mitochondrial
disease
• Biochemical
screening
• Neuromuscular
assessment
• Genetic testing
Adulthood Movement
disorder, peripheral
neuropathy, renal
dysfunction
• Anderson-Fabry
disease
• Friedrich's ataxia
• Infiltrative
disorders (eg,
amyloidosis)
• Glycogen storage
diseases
• Mitochondrial
disease
• Biochemical
screening
• Neuromuscular
assessment
• Genetic testing
