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[Figure: see text].

Many unrelated patients with the disorder for mutation in human desmosomal cadherin desmocollin-2 (DSC2) are investigated. The results have identified DSC2 mutations as a cause of arrhythmogenic right ventricular cardiomyopathy (ARVC) in humans and have shown that physiologic levels of DSC2 are crucial for normal cardiac desmosome formation, early cardiac morphogenesis and cardiac function.

The R6740 mutation of the MYH8 gene encoding perinatal myosin heavy chain causes a variant form of the carney complex associated with distal arthrogryposis, which includes typical spotty pigmentation of the skin, familial cardiac and cutaneous myxoma, and endocrinopathy. Novel roles for perinatal myosin in both the development of skeletal muscle and cardiac tumorigenesis are demonstrated.

Purpose: To evaluate the safety and potential efficacy of LLF580, a genetically engineered variant of human fibroblast growth factor-21, for triglyceride lowering, weight loss, and hepatic fat reduction. Methods: A multicenter, double-blind, parallel design trial in obese, mildly hypertriglyceridemic adults randomized (1:1) to LLF580 300 mg or placebo subcutaneously every 4 weeks for 3 doses. Results: Of 64 randomized study participants, 61 (mean ± SD: age 45 ± 11 years, 49% male, 80/15/5% Caucasian/African American/other, body mass index 36.1 ± 3.8 kg/m2) received LLF580 (n = 30) or placebo (n = 31) at 7 research sites in the United States. LLF580 lowered serum triglycerides by 54% (least square mean placebo adjusted change from baseline), total cholesterol 7%, low-density lipoprotein cholesterol 12%, and increased high-density lipoprotein cholesterol 36% compared with placebo (all P < 0.001) over 12 weeks. Substantial reduction of liver fat of 52% over placebo (P < 0.001) was also demonstrated in the setting of improved liver function tests including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, the composite enhanced liver fibrosis score, and N-terminal type III collagen propeptide (all P < 0.05). Insulin and C-peptide levels and insulin resistance by homeostatic model assessment for insulin resistance were all lower, and adiponectin higher with LLF580 treatment compared with placebo, whereas fasting glucose and glycated hemoglobin were unchanged. Reductions in biomarkers of bone formation without differences in markers of bone resorption were observed. LLF580 was generally safe and well tolerated, except for higher incidence of generally mild to moderate gastrointestinal adverse effects. Conclusions: In obese, mildly hypertriglyceridemic adults, LLF580 was generally safe and demonstrated beneficial effects on serum lipids, liver fat, and biomarkers of liver injury, suggesting it may be effective for treatment of select metabolic disorders including hypertriglyceridemia and nonalcoholic fatty liver disease. Assessments of longer term safety and efficacy are warranted. [ABSTRACT FROM AUTHOR]

A 27-year-old woman who began having episodes of fainting was found to have a heart tumor called a cardiac myxoma. She also had a history of Cushing's disease and freckles. She was diagnosed with a medical syndrome called Carney complex.

A mutation in the gene for the gamma2 regulatory subunit of AMP-activated protein kinase has been linked to a heart arrhythmia called Wolff-Parkinson-White syndrome. The arrhythmia is caused by an abnormal electrical pathway between the upper and lower parts of the heart.

Holt-Oram syndrome may be caused by mutations in a gene on chromosome 12q2. Holt-Oram syndrome is an inherited disorder characterized by skeletal deformities and heart defects. Researchers performed clinical and genetic-linkage studies on two large, unrelated families with the syndrome. In Family A, 26 of 49 members were affected and 18 surviving members were evaluated. All affected members of Family A had skeletal abnormalities and cardiovascular disease. Eleven had heart conduction diseases. In Family B, 18 of 31 affected members were still alive for examination. All affected family members had skeletal abnormalities and had severe skeletal deformities more frequently than affected members of Family A. In contrast, Family B had less severe and less frequent cardiovascular disease than Family A and only one member had a heart conduction disease. Genetic analysis revealed a linkage of the syndrome to mutations on chromosome 12.

Mutations in human TBXS, a member of the T-box transcription factor gene family, cause congenital cardiac septation defects and isomerism in autosomal dominant Holt-Oram syndrome. To determine the cellular function of TBX5 in cardiogenesis, we overexpressed wild-type and mutant human TBX5 isoforms in vitro and in vivo. TBX5 inhibited cell proliferation of D17 canine osteosarcoma cells and MEQC quail cardiomyocyte-like cells in vitro. Mutagenesis of the 5' end of the T-box but not the 3' end of the T-box abolished this effect. Overexpression of TBX5 in embryonic chick hearts showed that TBX5 inhibits myocardial growth and trabeculation. TBX5 effects in vivo were abolished by Gly80Arg missense mutation of the 5' end of the T-box. PCNA analysis in transgenic chick hearts revealed that TBX5 overexpression does suppress embryonic cardiomyocyte proliferation in vivo. Inhibitory effects of TBX5 on cardiomyocyte proliferation include a noncell autonomous process in vitro and in vivo. TBX5 inhibited proliferation of both nontransgenic cells cocultured with transgenic cells in vitro and nontransgenic cardiomyocytes in transgenic chick hearts with mosaic expression of TBX5 in vivo. Immunohistochemical studies of human embryonic tissues, including hearts, also demonstrated that TBX5 expression is inversely related to cellular proliferation. We propose that TBX5 can act as a cellular arrest signal during vertebrate cardiogenesis and thereby participate in modulation of cardiac growth and development.