How do you clinically differentiate syndromic obesity from non-syndromic obesity?

Syndromic obesity can be easily differentiated by the absence or presence of the following features:

1. Visual abnormalities
2. Developmental delay
3. Dysmorphic features

But, the following points show that there are exceptions to these rules:

Obesity Syndromes with Normal Vision

1. Cohen syndrome: V-shaped mouth, temper tantrums, and hyperphagia.

2. Prader Willi syndrome (PWS): Mental retardation, almond eyes, intrauterine hypotonia, temper tantrums, hypogonadism, and hypogonadotrophic.

Obesity with Abnormal Vision

1. Alstrom syndrome: normal stature, no mental retardation, vision abnormalities, and hypogonadotropic hypogonadism in the males only.

2. Laurence Moon Syndrome: hypogonadotrophic hypogonadism, spastic paraplegic, developmental delay.

3. Carpenter syndrome: flat nasal bridge, craniosynostosis, and distinctive factors with acrocephaly.