Background: Congenital leptin deficiency is a recessive genetic disorder associated with severe early-onset obesity. It is caused by mutations in the leptin (LEP) gene, which encodes the protein product leptin. These mutations may cause nonsense-mediated mRNA decay, defective secretion or the phenomenon of biologically inactive leptin, but typically lead to an absence of circulating leptin, resulting in a rare type of monogenic extreme obesity with intense hyperphagia, and serious metabolic abnormalities. Methods: We present two severely obese sisters from Colombia, members of the same lineal consanguinity. Their serum leptin was measured by MicroELISA. DNA sequencing was performed on MiSeq equipment (Illumina) of a next-generation sequencing (NGS) panel involving genes related to severe obesity, including LEP. Results: Direct sequencing of the coding region of LEP gene in the sisters revealed a novel homozygous missense mutation in exon 3 [NM_002303.3], C350G>T [p.C117F]. Detailed information and clinical measurements of these sisters were also collected. Their serum leptin levels were undetectable despite their markedly elevated fat mass. Conclusions: The mutation of LEP, absence of detectable leptin, and the severe obesity found in these sisters provide the first evidence of monogenic leptin deficiency reported in the continents of North and South America.
La resistencia a hormonas tiroideas (RHTs) es una causa rara de hipotiroidismo con una expresión clínica variable, que se caracteriza por una baja sensibilidad en los tejidos diana a la hormona tiroidea, con un perfil bioquímico que evidencia elevación de las hormonas tiroideas y tirotropina alta o inapropiadamente normal. Presentamos el caso de una paciente de 13 años con talla baja y desarrollo neurocognitivo bajo con perfil tiroideo con hormonas tiroideas elevadas y tirotropina inapropiadamente normal por lo cual se sospechó casusa central. Se descartaron causas estructurales, por lo cual se sospechó resistencia a hormonas tiroideas y se solicitaron estudios genéticos que confirmaron mutación de la subunidad ? del receptor de hormona tiroidea. Ante el compromiso neurocognitivo se inició manejo con triyodotironina.
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