Cullin 4B (CUL4B), lysosomal-associated membrane protein Type 2 (LAMP2), ATP1B4, TMEM255A, and ZBTB33 are neighboring genes on Xq24. Mutations in CUL4B result in Cabezas syndrome (CS). Male CS patients present with dysmorphic, neuropsychiatric, genitourinary, and endocrine abnormalities. Heterozygous CS females are clinically asymptomatic. LAMP2 mutations cause Danon disease (DD). Cardiomyopathy is a dominant feature of DD present in both males and heterozygous females. No monogenic phenotypes have been associated with mutations in ATP1B4, TMEM255A, and ZBTB33 genes. To facilitate diagnostics and counseling in CS and DD families, we present a female DD patient with a de novo Alu-mediated Xq24 rearrangement causing a deletion encompassing CUL4B, LAMP2, and also the other three neighboring genes. Typical to females heterozygous for CUL4B mutations, the patient was CS asymptomatic, however, presented with extremely skewed X-chromosome inactivation (XCI) ratios in peripheral white blood cells. As a result of the likely selection against CUL4B deficient clones, only minimal populations (~3%) of LAMP2 deficient leukocytes were identified by flow cytometry. On the contrary, myocardial LAMP2 protein expression suggested random XCI. We demonstrate that contiguous CUL4B and LAMP2 loss-of-function copy number variations occur and speculate that male patients carrying similar defects could present with features of both CS and DD.

• MeSH
• chromozomální delece MeSH
• dospělí MeSH
• elementy Alu genetika   MeSH
• exony genetika   MeSH
• glykogenóza typu IIb diagnóza   genetika   patofyziologie   MeSH
• inaktivace chromozomu X genetika   MeSH
• kardiomyopatie genetika   patofyziologie   MeSH
• kulinové proteiny genetika   MeSH
• lidé MeSH
• membránový protein 2 asociovaný s lyzozomy genetika   MeSH
• mentální retardace vázaná na chromozom X genetika   patofyziologie   MeSH
• mutace ztráty funkce genetika   MeSH
• myokard metabolismus   MeSH
• sodíko-draslíková ATPasa genetika   MeSH
• transkripční faktory genetika   MeSH
• variabilita počtu kopií segmentů DNA genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH

AIMS: Danon disease (DD) is a rare X-linked disorder caused by mutations in the lysosomal-associated membrane protein type 2 gene (LAMP2). DD is difficult to distinguish from other causes of dilated or hypertrophic cardiomyopathy (HCM) in female patients. As DD female patients regularly progress into advanced heart failure (AHF) aged 20-40 years, their early identification is critical to improve patient survival and facilitate genetic counselling. In this study, we evaluated the prevalence of DD among female patients with non-ischemic cardiomyopathy, who reached AHF and were younger than 40 years. METHODS AND RESULTS: The study cohort comprised 60 female patients: 47 (78%) heart transplant recipients, 2 (3%) patients treated with ventricular assist device, and 11 (18%) patients undergoing pre-transplant assessment. Aetiology of the cardiomyopathy was known in 15 patients (including two DD patients). LAMP2 expression in peripheral white blood cells (WBC) was tested by flow cytometry (FC) in the remaining 45 female patients. Whole exome sequencing was used as an alternative independent testing method to FC. Five additional female DD patients (two with different novel LAMP2 mutations) were identified by FC. The total prevalence of DD in this cohort was 12%. HCM phenotype (57% vs. 9%, * P = 0.022) and delta waves identified by electrocardiography (43% vs. 0%, ** P = 0.002) were significantly more frequent in DD female patients. CONCLUSIONS: Danon disease is an underdiagnosed cause of AHF in young female patients. LAMP2 expression testing in peripheral WBCs by FC can be used as an effective screening/diagnostic tool to identify DD in this patient population.

• MeSH
• fenotyp MeSH
• glykogenóza typu IIb * komplikace   diagnóza   epidemiologie   MeSH
• hypertrofická kardiomyopatie * komplikace   diagnóza   epidemiologie   MeSH
• lidé MeSH
• membránový protein 2 asociovaný s lyzozomy genetika   MeSH
• srdeční selhání * diagnóza   epidemiologie   etiologie   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Danon disease (DD) is an X-linked disorder caused by mutations in the lysosomal-associated membrane protein 2 (LAMP2) gene (Xq24). DD is characterized by cognitive deficit, myopathy, and cardiomyopathy in male patients. The phenotype is variable and mitigated in females. The timely identification of de-novo LAMP2 mutated family members, many of whom are heterozygous females, remains critical for their treatment and family counseling. DD laboratory testing builds on minimally invasive quantification of the LAMP2 protein in white blood cells and characterization of the specific mutation. This integrative approach is particularly helpful when assessing suspect female heterozygotes. LAMP2 exon-copy number variations (eCNVs) were so far reported only in X-hemizygous male DD probands. In heterozygous female DD probands, the wild-type allele may hamper the identification of an eCNV even if it results in the complete abolition of LAMP2 transcription and/or translation. To document the likely underappreciated rate of occurrence and point out numerous potential pitfalls of detection of the LAMP2 eCNVs, we present the first two DD heterozygote female probands who harbor novel multi-exon LAMP2 deletions. Critical for counseling and recurrence prediction, we also highlight the need to search for somatic-germinal mosaicism in DD families.

• MeSH
• dítě MeSH
• dospělí MeSH
• exony genetika   MeSH
• glykogenóza typu IIb genetika   MeSH
• heterozygot MeSH
• lidé MeSH
• membránový protein 2 asociovaný s lyzozomy genetika   MeSH
• mladiství MeSH
• mladý dospělý MeSH
• rodina MeSH
• rodokmen MeSH
• sekvence nukleotidů MeSH
• variabilita počtu kopií segmentů DNA genetika   MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH