👤 Jordi Bonaventura

Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare inherited white matter disorder. Initially, a "classic" phenotype has been characterized, presenting early-onset macrocephaly, cerebellar ataxia, mild spasticity, and a distinctive neuroimaging pattern of diffuse white matter abnormalities with subcortical cysts. An "improving" phenotype has also been described, featuring milder or absent neurological signs and a remitting pattern on neuroimaging. Mutations in four genes, MLC1, HEPACAM, GPRC5B and AQP4 have been associated with MLC. We describe clinical and genetic features of a cohort of genetically confirmed Italian MLC patients, representing the largest Italian cohort reported to date. We conducted a retrospective, multicenter, observational study. Patients were included based on clinical and neuroimaging features consistent with MLC, along with a confirmed genetic diagnosis. Data were collected using a standardized database and included demographic, clinical, neuroimaging, neurophysiological, and genetic information. Thirty-three patients from eight Italian centers were enrolled. Twenty-seven harbored biallelic MLC1 variants (23 distinct mutations, including three novel variants), while six had three distinct heterozygous HEPACAM variants. All MLC1-mutated patients exhibited the "classic" phenotype, frequently accompanied by orthopedic, gastrointestinal, and respiratory comorbidities. HEPACAM-mutated patients were consistent with the "improving" phenotype. No patients harbored mutations in GPRC5B or AQP4. Our findings expand the mutational spectrum of MLC1, further characterize the disease phenotype, and provide valuable insights into its presence in Italy. They also underscore management needs of individuals with MLC, highlighting the importance of multidisciplinary care. Show less

Hypertrophic cardiomyopathy (HCM) is a genetic myocardial disease. In 20% to 30% of patients, a disease-causing variant can be identified and may also be present in relatives. Individuals carrying a pathogenic variant (G+) without left ventricular hypertrophy (LVH) are classified as genotype-positive/phenotype-negative (G+/P-). Their risk of developing LVH or HCM-related events remains uncertain. The aim of the article is to describe the clinical course of G+/P- individuals during long-term follow-up. G+/P- individuals were recruited from relatives of HCM patients at a tertiary center. All underwent clinical assessment, electrocardiography (ECG), and transthoracic echocardiography (TTE). Phenotype-negative status was defined as maximal left ventricular wall thickness (MLVWT) <13 mm. HCM was diagnosed when MLVWT ≥13 mm was observed without hypertension or other hemodynamic causes. Genetic testing used targeted Sanger sequencing, with variants classified per ACMG/AMP criteria. Thirty-four individuals were classified as G+/P-; the mean age was 31.7 ± 14.8 years, and 27% were men. Variants occurred in MYBPC3 (76%) and MYH7 (24%). Most were asymptomatic (85%), and 71% had a normal ECG. Mean follow-up was 6.6 ± 3.7 years, with complete ECG and TTE data in 88%. MLVWT increased from 9.6 ± 1.6 mm to 10.7 ± 3.3 mm (p = 0.01), while other echocardiographic parameters and ECG findings remained stable. Nine individuals (26%) developed LVH after a mean of 5.1 ± 4.1 years. One patient developed nonsustained ventricular tachycardia and received a primary prevention implantable cardioverter-defibrillator. In conclusion, G+/P- individuals were young and largely asymptomatic, yet 26% progressed to HCM. These results support regular TTE and ECG surveillance to enable early identification of disease progression and guide risk stratification. Show less

The melanocortinergic neural circuit, known for its influence on energy expenditure and feeding behavior, also plays a role in stress and stress-induced psychiatric disorders, including anxiety and depression. The major contribution is given by the melanocortin-4 receptor (MC4R) subtype, highly expressed in brain regions involved in the control of stress responses. Furthermore, the MC4R appears to profoundly affect the activity of the hypothalamic-pituitary-adrenal (HPA) axis, and it has been also highlighted a functional and anatomical interaction with the corticotropin-releasing factor (CRF), an important mediator of stress and stress-related behaviors. The MC4R agonists seem to exacerbate stress-inducing anxiety- and depressive-like behavior, while MC4R antagonists have been demonstrated to mitigate such disorders, as shown in several preclinical behavioral tests. The evidence collected in the present review suggests that the melanocortin system, through the MC4R, could possibly modulate behavioral responses to stress, suggesting the use of MC4R antagonists as a possible novel treatment for anxiety and depression induced by stress. Show less

The dysfunction of melanocortin signaling has been associated with obesity, given the important role in the regulation of energy homeostasis, food intake, satiety and body weight. In the hypothalamus, the melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R) contribute to the stability of these processes, but MC3R and MC4R are also localized in the mesolimbic dopamine system, the region that responds to the reinforcing properties of highly palatable food (HPF) and where these two receptors seem to affect food reward and motivation. Loss of function of the MC4R, resulting from genetic mutations, leads to overeating in humans, but to date, a clear understanding of the underlying mechanisms and behaviors that promote overconsumption of caloric foods remains unknown. Moreover, the MC4R demonstrated to be a crucial modulator of the stress response, factor that is known to be strictly related to binge eating behavior. In this review, we will explore the preclinical and clinical studies, and the controversies regarding the involvement of melanocortin system in altered eating patterns, especially binge eating behavior, food reward and motivation. Show less

It is critical for survival to assign positive or negative valence to salient stimuli in a correct manner. Accordingly, harmful stimuli and internal states characterized by perturbed homeostasis are accompanied by discomfort, unease, and aversion. Aversive signaling causes extensive suffering during chronic diseases, including inflammatory conditions, cancer, and depression. Here, we investigated the role of melanocortin 4 receptors (MC4Rs) in aversive processing using genetically modified mice and a behavioral test in which mice avoid an environment that they have learned to associate with aversive stimuli. In normal mice, robust aversions were induced by systemic inflammation, nausea, pain, and κ opioid receptor-induced dysphoria. In sharp contrast, mice lacking MC4Rs displayed preference or indifference toward the aversive stimuli. The unusual flip from aversion to reward in mice lacking MC4Rs was dopamine dependent and associated with a change from decreased to increased activity of the dopamine system. The responses to aversive stimuli were normalized when MC4Rs were reexpressed on dopamine D1 receptor-expressing cells or in the striatum of mice otherwise lacking MC4Rs. Furthermore, activation of arcuate nucleus proopiomelanocortin neurons projecting to the ventral striatum increased the activity of striatal neurons in an MC4R-dependent manner and elicited aversion. Our findings demonstrate that melanocortin signaling through striatal MC4Rs is critical for assigning negative motivational valence to harmful stimuli. Show less