ABSTRACT
BACKGROUND: Early childhood obesity is a public health problem worldwide. It affects different aspects of physical and mental child's health. Identifying the etiologies, especially treatable and preventable causes, can direct health professionals toward proper management. Analysis of serum leptin levels and leptin gene mutations is a rapid and easy step toward the diagnosis of congenital leptin deficiency that is considered an important cause in early childhood obesity. OBJECTIVES: The aim of this study was to diagnose monogenic leptin deficiency in Egyptian children presenting with early onset obesity (EOO). METHODS: The current cross-sectional study included 80 children who developed obesity during the first year of life with BMI > 2 SD (for age and sex). The studied population was subjected to history taking, auxological assessment, serum leptin assay, and leptin gene sequencing. RESULTS: Ten cases had leptin deficiency (12.5%), while 18 cases showed elevated leptin levels (22.5%). Leptin gene variants in the coding region were identified in 30% of the leptin-deficient group: two novel homozygous disease-causing variants (c.104 T > G and c.34 delC) and another previously reported homozygous pathogenic variant (c.313C > T). CONCLUSION: Leptin deficiency is considered a significant cause of monogenic obesity in Egyptian children with early-onset obesity as the diagnosis of these patients would be a perfect target for recombinant leptin therapy.