Alström syndrome is a homogeneous autosomal recessive disorder that is characterized by childhood obesity associated with hyperinsulinemia, chronic hyperglycemia and neurosensory deficits 1,2 . The gene involved in Alström syndrome probably interacts with genetic modifiers, as subsets of affected individuals present with additional features such as dilated cardiomyopathy 3 , hepatic dysfunction 4 , hypothyroidism 5 , male hypogonadism, short stature and mild to moderate developmental delay, and with secondary complications normally associated with type 2 diabetes, such as hyperlipidemia and atherosclerosis. Our detection of an uncharacterized transcript, KIAA0328, led us to identify the gene ALMS1, which contains sequence variations, including four frameshift mutations and two nonsense mutations, that segregate with Alström syndrome in six unrelated families. ALMS1 is ubiquitously expressed at low levels and does not share significant sequence homology with other genes reported so far. The identification of ALMS1 provides an entry point into a new pathway leading toward the understanding of both Alström syndrome and the common diseases that characterize it.

. Maternal protein restriction leads to hyperinsulinemia and reduced insulin-signaling protein expression in 21-mo-old female rat offspring. Am J Physiol Regul Integr Comp Physiol 288: R368 -R373, 2005. First published October 28, 2004; doi:10.1152/ajpregu.00206.2004.-Human adult diseases such as cardiovascular disease, hypertension, and type 2 diabetes have been epidemiologically linked to poor fetal growth and development. Male offspring of rat dams fed a low-protein (LP) diet during pregnancy and lactation develop diabetes with concomitant alterations in their insulin-signaling mechanisms. Such associations have not been studied in female offspring. The aim of this study was to determine whether female LP offspring develop diabetes in later life. Control and LP female offspring groups were obtained from rat dams fed a control (20% protein) or an isocaloric (8% protein) diet, respectively, throughout pregnancy and lactation. Both groups were weaned and maintained on 20% normal laboratory chow until 21 mo of age when they underwent intravenous glucose tolerance testing (IVGTT). Fasting glucose was comparable between the two groups; however, LP fasting insulin was approximately twofold that of controls (P Ͻ 0.02). Glucose tolerance during IVGTT was comparable between the two groups; however, LP peak plasma insulin at 4 min was approximately threefold higher than in controls (P Ͻ 0.001). LP plasma insulin area under the curve was 1.9-fold higher than controls (P Ͻ 0.02). In Western blots, both muscle protein kinase C-expression and p110␤-associated p85␣ in abdominal fat were reduced (P Ͻ 0.05) in LPs. Hyperinsulinemia in response to glucose challenge coupled with attenuation of certain insulin-signaling molecules imply the development of insulin resistance in LP muscle and fat. These observations suggest that intrauterine protein restriction leads to insulin resistance in females in old age and, hence, an increased risk of type 2 diabetes. early growth restriction; protein kinase C-; females MANY EPIDEMIOLOGICAL STUDIES have revealed links between poor early human growth and susceptibility to type 2 diabetes, insulin resistance, and other features of the metabolic syndrome in adulthood (6). The mechanistic basis of this relationship is not known and the relative importance of genetic and environmental factors remains the subject of much debate. Rare mutations in the glucokinase gene have been shown to be associated to low birth weight and maturity-onset diabetes of the young 2 (10). However, a recent study of polymorphisms known to be associated with insulin resistance revealed no association with birth weight (14). The importance of the environment has been suggested in studies of individuals who were in utero during a period of famine (25). Further evidence for the importance of the environment has come from studies of twins (23, 2). The study of twins in Denmark showed that when there was discordance for type 2 diabetes, the diabetic twin had a significantly lower birth weight than the nondiabetic co-twin (2...

Alström syndrome is a monogenic recessive disorder featuring an array of clinical manifestations, with systemic fibrosis and multiple organ involvement, including retinal degeneration, hearing loss, childhood obesity, diabetes mellitus, dilated cardiomyopathy (DCM), urological dysfunction, and pulmonary, hepatic, and renal failure. We evaluated a large cohort of patients with Alström syndrome for mutations in the ALMS1 gene. In total, 79 disease-causing variants were identified, of which 55 are novel mutations. The variants are primarily clustered in exons 8, 10, and 16, although we also identified novel mutations in exons 12 and 18. Most alleles were identified only once (45/79), but several were found recurrently. Founder effects are likely in families of English and Turkish descent. We also identified 66 SNPs and assessed the functional significance of these variants based on the conserved identity of the protein and the severity of the resulting amino acid substitution. A genotype-phenotype association study examining 18 phenotypic parameters in a subset of 58 patients found suggestive associations between disease-causing variants in exon 16 and the onset of retinal degeneration before the age of 1 year (P = 0.02), the occurrence of urological dysfunction (P = 0.02), of DCM (P = 0.03), and of diabetes (P = 0.03). A significant association was found between alterations in exon 8 and absent, mild, or delayed renal disease (P = 0.0007). This data may have implications for the understanding of the molecular mechanisms of ALMS1 and provides the basis for further investigation of how alternative splicing of ALMS1 contributes to the severity of the disease.

A high percentage of patients with BRAF V600E mutant melanomas respond to the selective RAF inhibitor vemurafenib (RG7204, PLX4032) but resistance eventually emerges. To better understand the mechanisms of resistance, we used chronic selection to establish BRAF V600E melanoma clones with acquired resistance to vemurafenib. These clones retained the V600E mutation and no second-site mutations were identified in the BRAF coding sequence. Further characterization showed that vemurafenib was not able to inhibit extracellular signal-regulated kinase phosphorylation, suggesting pathway reactivation. Importantly, resistance also correlated with increased levels of RAS-GTP, and sequencing of RAS genes revealed a rare activating mutation in KRAS, resulting in a K117N change in the KRAS protein. Elevated levels of CRAF and phosphorylated AKT were also observed. In addition, combination treatment with vemurafenib and either a MAP/ERK kinase (MEK) inhibitor or an AKT inhibitor synergistically inhibited proliferation of resistant cells. These findings suggest that resistance to BRAF V600E inhibition could occur through several mechanisms, including elevated RAS-GTP levels and increased levels of AKT phosphorylation. Together, our data implicate reactivation of the RAS/RAF pathway by upstream signaling activation as a key mechanism of acquired resistance to vemurafenib, in support of clinical studies in which combination therapy with other targeted agents are being strategized to combat resistance. Cancer Res; 72(4); 969-78. Ó2011 AACR.

No abstract