Pietro Maffei

Mutations in ALMS1 cause obesity, type 2 diabetes and neurosensory degeneration in Alström syndrome.

Alström syndrome is a homogeneous autosomal recessive disorder that is characterized by childhood obesity associated with hyperinsulinemia, chronic hyperglycemia and neurosensory deficits. The gene involved in Alström syndrome probably interacts with genetic modifiers, as subsets of affected individuals present with additional features such as dilated cardiomyopathy, hepatic dysfunction, hypothyroidism, 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.

Alstr|[ouml]|m Syndrome

Alström Syndrome is an autosomal recessive, single gene disorder caused by mutations in ALMS1 (Chr 2p13), a novel gene of currently unknown molecular function. Alström Syndrome is multisystemic, with cone–rod retinal dystrophy leading to juvenile blindness, sensorineural hearing loss, obesity, insulin resistance with hyperinsulinemia, and type 2 diabetes mellitus. Very high incidences of additional disease phenotypes that may severely affect prognosis and survival include endocrine abnormalities, dilated cardiomyopathy, pulmonary fibrosis and restrictive lung disease, and progressive hepatic and renal failure. Other clinical features in some patients are hypertension, hypothyroidism, hyperlipidemia, hypogonadism, urological abnormalities, adult short stature, and bone-skeletal disturbances. Most patients demonstrate normal intelligence, although some reports indicate delayed psychomotor and intellectual development. The life span of patients with Alström Syndrome rarely exceeds 40 years. There is no specific therapy for Alström Syndrome, but early diagnosis and intervention can moderate the progression of the disease phenotypes and improve the longevity and quality of life for patients.

Alström Syndrome: Genetics and Clinical Overview

Alström syndrome is a rare autosomal recessive genetic disorder characterized by cone-rod dystrophy, hearing loss, childhood truncal obesity, insulin resistance and hyperinsulinemia, type 2 diabetes, hypertriglyceridemia, short stature in adulthood, cardiomyopathy, and progressive pulmonary, hepatic, and renal dysfunction. Symptoms first appear in infancy and progressive development of multi-organ pathology leads to a reduced life expectancy. Variability in age of onset and severity of clinical symptoms, even within families, is likely due to genetic background. Alström syndrome is caused by mutations in ALMS1, a large gene comprised of 23 exons and coding for a protein of 4,169 amino acids. In general, ALMS1 gene defects include insertions, deletions, and nonsense mutations leading to protein truncations and found primarily in exons 8, 10 and 16. Multiple alternate splice forms exist. ALMS1 protein is found in centrosomes, basal bodies, and cytosol of all tissues affected by the disease. The identification of ALMS1 as a ciliary protein explains the range of observed phenotypes and their similarity to those of other ciliopathies such as Bardet-Biedl syndrome. Studies involving murine and cellular models of Alström syndrome have provided insight into the pathogenic mechanisms underlying obesity and type 2 diabetes, and other clinical problems. Ultimately, research into the pathogenesis of Alström syndrome should lead to better management and treatments for individuals, and have potentially important ramifications for other rare ciliopathies, as well as more common causes of obesity and diabetes, and other conditions common in the general population.

Relationship between blood pressure and glucose tolerance in acromegaly

Hypertension represents a well‐known risk factor for cardiovascular diseases. The pathogenesis of hypertension in acromegaly is commonly viewed as multifactorial, but the possible influence of metabolic disorders on blood pressure (BP) in affected patients is largely unknown.

Effects of octreotide exposure during pregnancy in acromegaly

Background  Only six women who were treated with somatostatin analogues (SSAs) throughout their pregnancies have been described so far. The influence of SSAs on the course of pregnancy and newborn outcomes remains largely unknown. Many aspects of SSAs pharmacokinetics in mother and foetus have not yet been defined.

Alström Syndrome: Mutation Spectrum of ALMS1

Alström Syndrome (ALMS), a recessive, monogenic ciliopathy caused by mutations in ALMS1, is typically characterized by multisystem involvement including early cone‐rod retinal dystrophy and blindness, hearing loss, childhood obesity, type 2 diabetes mellitus, cardiomyopathy, fibrosis, and multiple organ failure. The precise function of ALMS1 remains elusive, but roles in endosomal and ciliary transport and cell cycle regulation have been shown. The aim of our study was to further define the spectrum of ALMS1 mutations in patients with clinical features of ALMS. Mutational analysis in a world‐wide cohort of 204 families identified 109 novel mutations, extending the number of known ALMS1 mutations to 239 and highlighting the allelic heterogeneity of this disorder. This study represents the most comprehensive mutation analysis in patients with ALMS, identifying the largest number of novel mutations in a single study worldwide. Here, we also provide an overview of all ALMS1 mutations identified to date.

The Alström Syndrome Protein, ALMS1, Interacts with α-Actinin and Components of the Endosome Recycling Pathway

Alström syndrome (ALMS) is a progressive multi-systemic disorder characterized by cone-rod dystrophy, sensorineural hearing loss, childhood obesity, insulin resistance and cardiac, renal, and hepatic dysfunction. The gene responsible for Alström syndrome, ALMS1, is ubiquitously expressed and has multiple splice variants. The protein encoded by this gene has been implicated in ciliary function, cell cycle control, and intracellular transport. To gain better insight into the pathways through which ALMS1 functions, we carried out a yeast two hybrid (Y2H) screen in several mouse tissue libraries to identify ALMS1 interacting partners. The majority of proteins found to interact with the murine carboxy-terminal end (19/32) of ALMS1 were α-actinin isoforms. Interestingly, several of the identified ALMS1 interacting partners (α-actinin 1, α-actinin 4, myosin Vb, rad50 interacting 1 and huntingtin associated protein1A) have been previously associated with endosome recycling and/or centrosome function. We examined dermal fibroblasts from human subjects bearing a disruption in ALMS1 for defects in the endocytic pathway. Fibroblasts from these patients had a lower uptake of transferrin and reduced clearance of transferrin compared to controls. Antibodies directed against ALMS1 N- and C-terminal epitopes label centrosomes and endosomal structures at the cleavage furrow of dividing MDCK cells, respectively, suggesting isoform-specific cellular functions. Our results suggest a role for ALMS1 variants in the recycling endosome pathway and give us new insights into the pathogenesis of a subset of clinical phenotypes associated with ALMS.

Mutation Detection in Patients with Retinal Dystrophies Using Targeted Next Generation Sequencing.

Retinal dystrophies (RD) constitute a group of blinding diseases that are characterized by clinical variability and pronounced genetic heterogeneity. The different nonsyndromic and syndromic forms of RD can be attributed to mutations in more than 200 genes. Consequently, next generation sequencing (NGS) technologies are among the most promising approaches to identify mutations in RD. We screened a large cohort of patients comprising 89 independent cases and families with various subforms of RD applying different NGS platforms. While mutation screening in 50 cases was performed using a RD gene capture panel, 47 cases were analyzed using whole exome sequencing. One family was analyzed using whole genome sequencing. A detection rate of 61% was achieved including mutations in 34 known and two novel RD genes. A total of 69 distinct mutations were identified, including 39 novel mutations. Notably, genetic findings in several families were not consistent with the initial clinical diagnosis. Clinical reassessment resulted in refinement of the clinical diagnosis in some of these families and confirmed the broad clinical spectrum associated with mutations in RD genes.

ALMS1-deficient fibroblasts over-express extra-cellular matrix components, display cell cycle delay and are resistant to apoptosis.

Alström Syndrome (ALMS) is a rare genetic disorder (483 living cases), characterized by many clinical manifestations, including blindness, obesity, type 2 diabetes and cardiomyopathy. ALMS is caused by mutations in the ALMS1 gene, encoding for a large protein with implicated roles in ciliary function, cellular quiescence and intracellular transport. Patients with ALMS have extensive fibrosis in nearly all tissues resulting in a progressive organ failure which is often the ultimate cause of death. To focus on the role of ALMS1 mutations in the generation and maintenance of this pathological fibrosis, we performed gene expression analysis, ultrastructural characterization and functional assays in 4 dermal fibroblast cultures from ALMS patients. Using a genome-wide gene expression analysis we found alterations in genes belonging to specific categories (cell cycle, extracellular matrix (ECM) and fibrosis, cellular architecture/motility and apoptosis). ALMS fibroblasts display cytoskeleton abnormalities and migration impairment, up-regulate the expression and production of collagens and despite the increase in the cell cycle length are more resistant to apoptosis. Therefore ALMS1-deficient fibroblasts showed a constitutively activated myofibroblast phenotype even if they do not derive from a fibrotic lesion. Our results support a genetic basis for the fibrosis observed in ALMS and show that both an excessive ECM production and a failure to eliminate myofibroblasts are key mechanisms. Furthermore, our findings suggest new roles for ALMS1 in both intra- and extra-cellular events which are essential not only for the normal cellular function but also for cell-cell and ECM-cell interactions.

Increased Rate of Intracranial Saccular Aneurysms in Acromegaly: An MR Angiography Study and Review of the Literature

BACKGROUND The concurrence of intracranial aneurysms and acromegaly has been reported and debated previously. Our study in a large number of patients aimed to verify whether acromegaly patients carry a higher risk of harboring intracranial saccular aneurysms and to evaluate the possible relationship using clinical, laboratory, and imaging techniques. MATERIALS AND METHODS A total of 152 of 161 consecutive acromegaly patients (median age, 55.7 yr; 82 females) underwent neuroimaging evaluation of the circle of Willis. Clinical data (disease duration and disease control, hypertension, smoking history, diabetes and dyslipidemia, previous surgery or radiotherapy, previous or current pharmacological therapy), laboratory findings (GH and IGF-I at onset and shortly before examination), and pituitary adenoma imaging features (size and invasiveness of the cavernous sinus) were recorded. RESULTS Twenty-six patients (17.3%) harbored 40 newly diagnosed intracranial aneurysms; two other patients had previously undergone aneurysm clipping due to subarachnoid hemorrhage. Ten patients had multiple aneurysms; most of the aneurysms were located in the intracranial tract of the internal carotid artery (67.5%); no aneurysms belonged to the vertebrobasilar circulation. The presence of intracranial aneurysms correlated with GH serum values at disease onset (P < 0.05) and showed a trend to a positive correlation with poor disease control (P = 0.06); no other laboratory, clinical, and radiological findings correlated with the presence of intracranial aneurysms. CONCLUSIONS GH serum excess seems to carry an increased risk of developing intracranial aneurysms. A neuroradiological evaluation of the intracranial circulation might therefore be considered in the diagnostic work-up of patients affected with acromegaly.