RESUMO
Sitosterolemia is an autosomal recessive and very rare disease. Its main characteristic is that there is a greater absorption and a decrease in the excretion of sterols, which leads to them being deposited in tissues. It is given by mutations in the ABCG5 or ABCG8 genes found on chromosome 2p21. In this clinical note, we describe the first two patients with familial sitosterolemia described in Colombia, brothers, one of them with xanthomas in extremities as the only symptom, and the other, completely asymptomatic. Genetic studies were performed as a diagnostic test in both patients, where a pathogenic homozygous variant could be identified in the ABCG8 gene in the first case (symptomatic), and a heterozygous variant in the ABCG8 gene in the second case (asymptomatic); the first patient has responded to treatment with ezetimibe. In conclusion, xanthomas should be studied in depth in pediatric age as they may be the only visible sign of such complex and hereditary diseases as familial sitosterolemia, which can be controlled and prevent cardiovascular complications of the disease.
Assuntos
Membro 8 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Ezetimiba , Hipercolesterolemia , Enteropatias , Erros Inatos do Metabolismo Lipídico , Fitosteróis , Humanos , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/diagnóstico , Masculino , Colômbia , Fitosteróis/efeitos adversos , Fitosteróis/genética , Enteropatias/genética , Enteropatias/diagnóstico , Membro 8 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Hipercolesterolemia/genética , Hipercolesterolemia/tratamento farmacológico , Hipercolesterolemia/diagnóstico , Ezetimiba/uso terapêutico , Xantomatose/genética , Xantomatose/patologia , Xantomatose/diagnóstico , Anticolesterolemiantes/uso terapêutico , Anticolesterolemiantes/administração & dosagem , Mutação , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Homozigoto , Criança , Heterozigoto , Lipoproteínas/genéticaRESUMO
PURPOSE OF REVIEW: The purpose of this review was to summarize important and updated information on sitosterolemia. Sitosterolemia is an inherited lipid disorder consisting of high levels of plasma plant sterols. This sterol storage condition is caused by biallelic loss-of-function genetic variants in either ABCG5 or ABCG8, leading to increased intestinal absorption and decreased hepatic excretion of plant sterols. Clinically, patients with sitosterolemia usually exhibit xanthomatosis, high levels of plasma cholesterol, and premature atherosclerotic disease, but presentation can be highly heterogeneous. Therefore, recognition of this condition requires a high level of suspicion, with confirmation upon genetic diagnosis or through measurement of plasma phytosterols. Treatment of sitosterolemia with both a plant sterol-restricted diet and the intestinal cholesterol absorption inhibitor ezetimibe can reduce efficiently the levels of plasma plant sterols, consisting in the first-line therapy for this disease. RECENT FINDINGS: Since hypercholesterolemia is often present in individuals with sitosterolemia, it is important to search for genetic variants in ABCG5 and ABCG8 in patients with clinical criteria for familial hypercholesterolemia (FH), but no variants in FH implicated genes. Indeed, recent studies have suggested that genetic variants in ABCG5/ABCG8 can mimic FH, and even when in heterozygosis, they may potentially exacerbate the phenotype of patients with severe dyslipidemia. Sitosterolemia is a genetic lipid disorder characterized by increased circulating levels of plant sterols and clinically manifested by xanthomatosis, hematologic disorders, and early atherosclerosis. Awareness about this condition, a rare, but commonly underdiagnosed and yet treatable cause of premature atherosclerotic disease, is imperative.
Assuntos
Aterosclerose , Hipercolesterolemia , Hiperlipoproteinemia Tipo II , Enteropatias , Erros Inatos do Metabolismo Lipídico , Fitosteróis , Xantomatose , Humanos , Hipercolesterolemia/tratamento farmacológico , Fitosteróis/efeitos adversos , Fitosteróis/genética , Erros Inatos do Metabolismo Lipídico/diagnóstico , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/terapia , Enteropatias/diagnóstico , Enteropatias/genética , Enteropatias/tratamento farmacológico , Hiperlipoproteinemia Tipo II/complicações , Colesterol , Xantomatose/etiologia , Aterosclerose/genética , Aterosclerose/complicaçõesRESUMO
Snakin-1 is a member of the Solanum tuberosum Snakin/GASA family. We previously demonstrated that Snakin-1 is involved in plant defense to pathogens as well as in plant growth and development, but its mechanism of action has not been completely elucidated yet. Here, we showed that leaves of Snakin-1 silenced potato transgenic plants exhibited increased levels of reactive oxygen species and significantly reduced content of ascorbic acid. Furthermore, Snakin-1 silencing enhanced salicylic acid content in accordance with an increased expression of SA-inducible PRs genes. Interestingly, gibberellic acid levels were also enhanced and transcriptome analysis revealed that a large number of genes related to sterol biosynthesis were downregulated in these silenced lines. Moreover, we demonstrated that Snakin-1 directly interacts with StDIM/DWF1, an enzyme involved in plant sterols biosynthesis. Additionally, the analysis of the expression pattern of PStSN1::GUS in potato showed that Snakin-1 is present mainly in young tissues associated with active growth and cell division zones. Our comprehensive analysis of Snakin-1 silenced lines demonstrated for the first time in potato that Snakin-1 plays a role in redox balance and participates in a complex crosstalk among different hormones.
Assuntos
Reguladores de Crescimento de Plantas , Folhas de Planta , Proteínas de Plantas , Plantas Geneticamente Modificadas , Solanum tuberosum , Fitosteróis/biossíntese , Fitosteróis/genética , Reguladores de Crescimento de Plantas/genética , Reguladores de Crescimento de Plantas/metabolismo , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/biossíntese , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo , Solanum tuberosum/genética , Solanum tuberosum/metabolismoRESUMO
Sitosterolemia is an autosomal recessive metabolic disease caused by mutations in ABCG5 or ABCG8 genes which encode for the (ATP)-binding cassette (ABC) transporters that are responsible for the trafficking of xenosterols. Liver involvement is not a recognized manifestation of this disease, and cirrhosis has been reported only once in the medical literature. We describe a fatal case of a 21-year old South Asian male who presented with decompensated cirrhosis, and biochemical abnormalities consistent with sitosterolemia. Genetic testing showed a homozygous pathogenic mutation in ABCG5, confirming the diagnosis. Sitosterolemia is a rare, but likely under-recognized condition, and a high degree of suspicion is imperative to make the diagnosis. We propose that sitosterolemia should be included in the differential diagnosis for patients with cryptogenic cirrhosis, especially as there are effective oral therapies to treat this condition. Newly diagnosed sitosterolemia patients should undergo a thorough hepatology evaluation and follow-up to evaluate for the presence, development, and progression of any hepatic involvement.
Assuntos
Hipercolesterolemia/complicações , Enteropatias/complicações , Erros Inatos do Metabolismo Lipídico/complicações , Cirrose Hepática/etiologia , Fitosteróis/efeitos adversos , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Anemia Hemolítica/etiologia , Anticolesterolemiantes/uso terapêutico , Biópsia , Angiografia Coronária , Doença da Artéria Coronariana/etiologia , Análise Mutacional de DNA , Dieta com Restrição de Gorduras , Ezetimiba/uso terapêutico , Evolução Fatal , Predisposição Genética para Doença , Hereditariedade , Homozigoto , Humanos , Hipercolesterolemia/diagnóstico , Hipercolesterolemia/genética , Hipercolesterolemia/terapia , Enteropatias/diagnóstico , Enteropatias/genética , Enteropatias/terapia , Erros Inatos do Metabolismo Lipídico/diagnóstico , Erros Inatos do Metabolismo Lipídico/genética , Erros Inatos do Metabolismo Lipídico/terapia , Lipoproteínas/genética , Cirrose Hepática/diagnóstico , Masculino , Microscopia Eletrônica , Mutação , Linhagem , Fenótipo , Fitosteróis/genética , Fatores de Risco , Resultado do Tratamento , Xantomatose/etiologia , Adulto JovemRESUMO
Sitosterolemia is a disease characterized by an intestinal hyperabsorption of plant sterols and cholesterol. Affected individuals have mutations in both alleles of either ABCG5 or ABCG8 genes, leading to a total loss of one of the proteins and subsequent functional deficiency. We here report a Mexican family with clinical and biochemical features of sitosterolemia carrying 2 new mutations of the ABCG5 gene. Concentrations of sitosterol, campesterol, and cholesterol were found to be higher for the index case (a 10-year-old girl) than for her also affected sibling (64.1 vs 19 mg/dL, 32 vs 12.1 mg/dL, and cholesterol 295 vs 235 mg/dL, respectively). Both individuals showed 2 new ABCG5 gene mutations identified by sequencing, which is concordant with their biochemical diagnosis of sitosterolemia. The first mutation was a c.144 -1G>A transition that disrupts the intron 1 splicing acceptor site. The second mutation is the deletion c.1523 delC, which occurred in exon 11, causing an amino acid change at codon 510 (p.His510Thr) and a stop codon at codon 511 (p.Leu511X). The father is heterozygote for the mutation c.144 -1G>A, whereas the mother is heterozygote for the mutation c.1523 delC. In conclusion, we here report the first case of a Mexican family with sitosterolemia carrying two new ABCG5 gene mutations.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Hipercolesterolemia/genética , Enteropatias/genética , Erros Inatos do Metabolismo Lipídico/genética , Lipoproteínas/genética , Mutação , Linhagem , Fitosteróis/efeitos adversos , Membro 5 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Adolescente , Sequência de Bases , Criança , Feminino , Humanos , Masculino , México , Pessoa de Meia-Idade , Dados de Sequência Molecular , Fitosteróis/genética , Adulto JovemRESUMO
Brassinosteroids (BRs) are plant steroid hormones and, when applied exogenously, they induce physiological responses, including tolerance to heat shock (HS). How endogenous BR content and altered perception of BRs influence thermal tolerance is poorly understood. BR-induced thermotolerance in tomato seedlings with altered BR homeostasis was examined by assessing the survival, ion leakage and lipid peroxidation of seedlings from a BR-deficient mutant (extreme dwarf d(x)), a partially BR-insensitive mutant curl3(-abs) allele (curl3 altered brassinolide sensitivity) and a line overexpressing the Dwarf, BR-biosynthesis gene (35SD). We confirmed that treatment with 1 µM of epi-brassinolide (EBL) induces thermotolerance of wild type seedlings following a HS regime at 45 °C. The curl3(-abs) seedlings had the highest basal tolerance to heat, whereas the EBL-induced thermal tolerance of d(x) seedlings was greatest and responded to lower EBL concentrations. The d(x) and 35SD seedlings had similar thermal tolerance; however, they showed increased signs of oxidative stress. EBL reduced the induction of lipid peroxidation of seedlings after recovery from heat. Highest oxidative stress and peroxidase (POX) activity (EC 1.11.1.7) was in BR-deficient d(x) mutant seedlings. EBL was able of inducing POX activity but not other antioxidant enzymes; however, effects of HS on POX activity of seedlings were absent or less marked. Taking together, results indicate that thermal tolerance is independent of endogenous BR content, but HS-mediated oxidative stress depends on BR levels.