Sara Missaglia

Prevalence of mutations in LEP, LEPR, and MC4R genes in individuals with severe obesity.

Obesity is a major public health concern; despite evidence of high heritability, the genetic causes of obesity remain unclear. In this study, we assessed the presence of mutations in three genes involved in the hypothalamic leptin-melanocortin regulation pathway (leptin, LEP; leptin receptor, LEPR; and melanocortin-4 receptor, MC4R), which is important for energy homeostasis in the body, in a group of patients with severe obesity. For this study, we selected 77 patients who had undergone bariatric surgery and had a pre-operative body mass index (BMI) >35 kg/m2, early onset and a family history of being overweight. Candidate genes were screened by direct sequence analysis to search for rare genetic variations. The common LEP -2548 G/A polymorphism was also evaluated for its influence on the BMI (in obesity patients) and for obesity risk, using a case-control study involving 117 healthy individuals. Two different non-synonymous alterations in MC4R were found in two patients: the p.(Thr112Met), previously described in the literature as a probable gene involved in the obesity phenotype, and the novel p.(Tyr302Asp) variant, predicted to be pathogenic by in silico evaluations and family segregation studies. The LEP -2548 G/A polymorphism was not associated with the BMI or obesity risk. In conclusion, we have reported a novel mutation in MC4R in a family of Italian patients with severe obesity. Screening for MC4R could be important for directing the carriers of mutations towards therapy including partial agonists of the MC4R that could normalize their appetite and inhibit compulsive eating. Next-generation sequencing could be used to clarify the genetic basis of obesity in the future.

Harm avoidance moderates the influence of serotonin transporter gene variants on treatment outcome in bipolar patients

Response to pharmacological treatments is moderated by both genetic and environmental factors. The contribution of such factors is relatively small and complex interactions are likely to be involved. Serotonin transporter gene (SLC6A4) is a major candidate gene associated to response to antidepressant treatment. Moreover, the 5-HTTLPR polymorphism has been associated with anxiety-related traits such as neuroticism and harm avoidance (HA), which are known to influence the risk to develop mood disorders and response to treatments. In the present study we aimed to investigate the interaction between 3 SLC6A4 variants and HA on medium term antidepressant response in a sample of depressed bipolar-spectrum patients followed for 12 months. Contrary to expectations, SLC6A4 variants did significantly influence neither the course of depressive symptoms nor HA scores. However, a significant interaction was observed between HA and 5-HTTLPR genotype. Indeed, a high HA impaired outcome in patients carrying the L(G)/S or the S/S genotype more than in L(A)/L(A) patients. Though a number of limitations characterize the present study, our results indicate HA as a potential moderator of the effect of 5-HTTLPR on the outcome of depression. Given that many factors may influence response to pharmacological treatments, studies that consider personality and other individual characteristics are warranted also in pharmacogenetic investigations.

Contribution of novel ATGL missense mutations to the clinical phenotype of NLSD-M: a strikingly low amount of lipase activity may preserve cardiac function

The lack of adipose triglyceride lipase (ATGL), a patatin-like phospholipase domain-containing enzyme that hydrolyzes fatty acids from triacylglycerol (TAG) stored in multiple tissues, causes the autosomal recessive disorder neutral lipid storage disease with myopathy (NLSD-M). In two families of Lebanese and Italian origin presenting with NLSD-M, we identified two new missense mutations in highly conserved regions of ATGL (p.Arg221Pro and p.Asn172Lys) and a novel nonsense mutation (p.Trp8X). The Lebanese patients harbor homozygous p.Arg221Pro, whereas the Italian patients are heterozygotes for p.Asn172Lys and the p.Trp8X mutation. The p.Trp8X mutation results in a complete absence of ATGL protein, while the p.Arg221Pro and p.Asn172Lys mutations result in proteins with minimal lipolytic activity. Although these mutations did not affect putative catalytic residues or the lipid droplet (LD)-binding domain of ATGL, cytosolic LDs accumulated in cultured skin fibroblasts from the patients. The missense mutations might destabilize a random coil (p.Asn172Lys) or a helix (p.Arg221Pro) structure within or proximal to the patatin domain of the lipase, thereby interfering with the enzyme activity, while leaving intact the residues required to localize the protein to LDs. Overexpressing wild-type ATGL in one patients fibroblasts corrected the metabolic defect and effectively reduced the number and area of cellular LDs. Despite the poor lipase activity in vitro, the Lebanese siblings have a mild myopathy and not clinically evident myocardial dysfunction. The patients of Italian origin show a late-onset and slowly progressive skeletal myopathy. These findings suggest that a small amount of correctly localized lipase activity preserves cardiac function in NLSD-M.

Further evidence supporting the influence of brain-derived neurotrophic factor on the outcome of bipolar depression: independent effect of brain-derived neurotrophic factor and harm avoidance

Brain-derived neurotrophic factor is a candidate gene for response to antidepressant treatment. However, response to pharmacological treatments is moderated by both genetic and other factors within individuals. For example, there is evidence of an influence of the temperamental trait of harm avoidance on the outcome of depressive disorders. In the present study we aimed to investigate the effect of the brain-derived neurotrophic factor gene on medium-term outcome in a naturalistic sample of 86 depressed bipolar spectrum patients, taking into account harm avoidance. Both single marker and haplotypes were significantly associated with severity of depression at month 6 after treatment initiation. The haplotype comprising the A-C alleles was associated with a poorer outcome. Harm avoidance maintained a significant effect on depressive outcome in bipolar disorder, independently from brain-derived neurotrophic factor genotypes. However, harm avoidance s influence appeared to be more consistent in patients carrying the protective G-T combination of alleles. Our results indicate brain-derived neurotrophic factor as involved in the outcome of depression in bipolar disorder. Harm avoidance did not interact with brain-derived neurotrophic factor genotypes, though its effect was still significant. Given that many factors may influence response to pharmacological treatments, studies that consider personality and other individual characteristics are warranted also in pharmacogenetic investigations.

Novel missense mutations in PNPLA2 causing late onset and clinical heterogeneity of neutral lipid storage disease with myopathy in three siblings

Neutral lipid storage disease with myopathy (NLSD-M) is a rare autosomal recessive disorder characterised by an abnormal accumulation of triacylglycerol into cytoplasmic lipid droplets (LDs). NLSD-M patients are mainly affected by progressive myopathy, cardiomyopathy and hepatomegaly. Mutations in the PNPLA2 gene cause variable phenotypes of NLSD-M. PNPLA2 codes for adipose triglyceride lipase (ATGL), an enzyme that hydrolyses fatty acids from triacylglycerol. This report outlines the clinical and genetic findings in a NLSD-M Italian family with three affected members. In our patients, we identified two novel PNPLA2 missense mutations (p.L56R and p.I193F). Functional data analysis demonstrated that these mutations caused the production of ATGL proteins able to bind to LDs, but with decreased lipase activity. The oldest brother, at the age of 38, had weakness and atrophy of the right upper arm and kyphosis. Now he is 61 years old and is unable to raise arms in the horizontal position. The second brother, from the age of 44, had exercise intolerance, cramps and pain in lower limbs. He is currently 50 years old and has an asymmetric distal amyotrophy. One of the two sisters, 58 years old, presents the same PNPLA2 mutations, but she is still oligo-symptomatic on neuromuscular examination with slight triceps muscle involvement. She suffered from diabetes and liver steatosis. This NLSD-M family shows a wide range of intra-familial phenotypic variability in subjects carrying the same mutations, both in terms of target-organs and in terms of rate of disease progression.

A late-onset case of neutral lipid storage disease with myopathy, dropped head syndrome, and peripheral nerve involvement

Neutral lipid storage disease with myopathy (NLSDM) is a rare autosomal recessive disorder of neutral lipid metabolism. Clinical manifestations include progressive skeletal myopathy, cardiomyopathy, and liver dysfunction. Clinical severity is variable and additional symptoms may include diabetes mellitus, chronic pancreatitis, hypothyroidism, neurosensory hearing loss, and short stature. We report a 79-year-old man with progressive proximal arm weakness, lipid storage myopathy, dropped head syndrome, and peripheral nervous system involvement. He harboured a novel homozygous missense mutation, c.570A>C (p.S191R) in the patatin-like phospholipase domain containing 2 (PNPLA2) gene, confirming the diagnosis of NLSDM. The S191R mutation causes late-onset NLSDM without cardiac dysfunction. The previously unreported association with dropped head syndrome expands the clinical spectrum of NLSDM.

A myopathy with unusual features caused by PNPLA2 gene mutations

Introduction: The PNPLA2 gene encodes the enzyme adipose triglyceride lipase (ATGL), which catalyzes the first step of triglyceride hydrolysis. Mutations in this gene are associated with an autosomal recessive lipid‐storage myopathy, neutral lipid‐storage disease with myopathy (NLSD‐M). Results: A 72‐year‐old woman had late‐onset myopathy, with mild weakness, cramps, and exercise intolerance. Electromyography showed myotonic discharges. A few leukocytes showed lipid droplets (Jordan anomaly). Deltoid and quadriceps muscle biopsies showed no lipid storage. Genetic analysis of PNPLA2 detected 2 heterozygous mutations: c.497A>G (p.Asp166Gly) in exon 5 and c.1442C>T (p.Pro481Leu) in exon 10. Expression of mutant PNPLA2 plasmids in HeLa cells resulted in impaired enzyme activity, confirming the pathological effects of the mutations. Conclusions: In this case of NLSD‐M, the myopathy may be due to a metabolic defect rather than to a mechanical effect of lipid storage. This suggests that more than 1 mechanism contributes to muscle damage in NLSD‐M. Muscle Nerve 51: 609–613, 2015

Further evidence supporting the association between 5HTR2C gene and bipolar disorder.

Three 5HTR2C polymorphisms were investigated in bipolar (BD) spectrum disorders. The functional rs6318 G (Cys) allele was more frequent in BD patients than in controls (P=0.0036). Thus, 5HTR2C may have a role in BD. Further investigation is required to understand its involvement in co-morbidity for substance use disorders (SUDs).

Late onset of neutral lipid storage disease due to novel PNPLA2 mutations causing total loss of lipase activity in a patient with myopathy and slight cardiac involvement

Highlights • Two novel mutations in PNPLA2 gene have been identified in a neutral lipid storage disease with myopathy (NLSDM) female patient.• The mutations are located in exon 5 of PNPLA2 and abrogate lipase function.• The patient showed late onset skeletal muscle myopathy and mild cardiac impairment.• Clinical cardiac phenotype is milder in NLSDM female patients, beyond genetics.

Heterogeneous Phenotypes in Lipid Storage Myopathy Due to ETFDH Gene Mutations

We present six novel patients affected by lipid storage myopathy (LSM) presenting mutations in the ETFDH gene. Although the diagnosis of multiple acyl-coenzyme-A dehydrogenase deficiency (MADD) in adult life is difficult, it is rewarding because of the possibility of treating patients with carnitine or riboflavin, leading to a full recovery. In our patients, a combination of precipitating risk factors including previous anorexia, alcoholism, poor nutrition, and pregnancy contributed to a metabolic critical condition that precipitated the catabolic state.In the present series of cases, five novel mutations have been identified in the ETFDH gene. We propose clinical guidelines to screen patients with LSM due to different defects, in order to obtain a fast diagnosis and offer appropriate treatment. In such patients, early diagnosis and treatment as well as avoiding risk factors are part of clinical management.Specific biochemical studies are indicated to identify the type of LSM, such as level of free carnitine and acyl-carnitines and studies or organic acidemia. Indeed, when a patient is biochemically diagnosed with secondary carnitine deficiency, a follow-up with appropriate clinical-molecular protocol and genetic analysis is important to establish the final diagnosis, since riboflavin can be supplemented with benefit if riboflavin-responsive MADD is present. In muscle biopsies, increased lipophagy associated with p62-positive aggregates was observed. The clinical improvement can be attributed to the removal of an autophagic block, which appears to be reversible in this LSM.