Classification of Congenital Leptin Deficiency

Area of Science:

• Genetics
• Endocrinology
• Molecular Biology

Background:

• Biallelic pathogenic leptin gene variants lead to severe early-onset obesity.
• These variants are often associated with low or undetectable circulating leptin levels.
• Recently identified variants result in secreted mutant leptin forms with inactive or antagonistic properties.

Purpose of the Study:

• To systematically classify congenital leptin deficiency based on molecular and functional characteristics of leptin variants.
• To investigate the correlation between disease subtype and clinical phenotype severity.
• To guide individualized treatment approaches for patients with congenital leptin deficiency.

Main Methods:

• Systematic literature research.
• Inclusion of unpublished patient data.
• In vitro analyses of leptin variants.
• Correlation analysis between variant type and clinical phenotype.

Main Results:

• 28 distinct homozygous leptin variants identified in 148 patients.
• Three subtypes identified: classical hormone deficiency (21 variants, 128 patients), biologically inactive hormone (3 variants, 12 patients), and antagonistic hormone (3 variants, 7 patients).
• Patients with biologically inactive leptin showed higher BMI percentiles than those with classical deficiency; antagonistic variants require tailored treatment.

Conclusions:

• Categorizing leptin variants by molecular and functional characteristics is crucial.
• This classification aids in determining the most effective treatment strategies for congenital leptin deficiency.
• Personalized treatment approaches, especially for antagonistic variants, are essential for optimal patient outcomes.