Danon disease as an underrecognized cause of hypertrophic cardiomyopathy in children.
BACKGROUND
Some patients with hypertrophic cardiomyopathy (HCM) or left ventricular hypertrophy also present with skeletal myopathy and Wolff-Parkinson-White (WPW) syndrome; mutations in the gene encoding the lysosome-associated protein-2 (LAMP-2) have been identified in these patients, suggesting that some of these patients have Danon disease. In this study we investigated the frequency of LAMP2 mutations in an unselected pediatric HCM population.


RESULTS
LAMP2 was amplified from genomic DNA isolated from peripheral lymphocytes of 50 patients diagnosed with HCM and analyzed by direct DNA sequencing. In 2 of the 50 probands (4%), nonsense mutations were identified. In 1 family the proband initially presented with HCM as a teenager, which progressed to dilated cardiomyopathy (DCM) and heart failure. Skeletal myopathy and WPW were also noted. The teenage sister of the proband is a carrier of the same LAMP2 mutation and has HCM without skeletal myopathy or WPW. The other proband presented with HCM, WPW, and skeletal myopathy as a teenager, whereas his carrier mother developed DCM during her 40s. Skeletal and cardiac muscle sections revealed the absence of LAMP-2 on immunohistochemical staining.


CONCLUSIONS
LAMP2 mutations may account for a significant proportion of cases of HCM in children, especially when skeletal myopathy and/or WPW is present, suggesting that Danon disease is an underrecognized entity in the pediatric cardiology community.
Yang
Zhao
Z
Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA.
McMahon
Colin J
CJ
Smith
Liana R
LR
Bersola
Jeathrina
J
Adesina
Adekunle M
AM
Breinholt
John P
JP
Kearney
Debra L
DL
Dreyer
William J
WJ
Denfield
Susan W
SW
Price
Jack F
JF
Grenier
Michelle
M
Kertesz
Naomi J
NJ
Clunie
Sarah K
SK
Fernbach
Susan D
SD
Southern
James F
JF
Berger
Stuart
S
Towbin
Jeffrey A
JA
Bowles
Karla R
KR
Bowles
Neil E
NE
D000293:Adolescent; D002312:Cardiomyopathy, Hypertrophic / Q000209:etiology* / Q000235:genetics* / Q000473:pathology; D002648:Child; D002675:Child, Preschool; D018389:Codon, Nonsense; D015331:Cohort Studies; D005260:Female; D005455:Fluorescent Antibody Technique; D005787:Gene Frequency; D052120:Glycogen Storage Disease Type IIb / Q000150:complications* / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009135:Muscular Diseases / Q000209:etiology; D009206:Myocardium / Q000378:metabolism; D010210:Papillary Muscles / Q000473:pathology; D014927:Wolff-Parkinson-White Syndrome / Q000209:etiology
D018389:Codon, Nonsense; C497811:LAMP2 protein, human; D052119:Lysosomal-Associated Membrane Protein 2; D051907:Lysosomal Membrane Proteins