**Core Concept**
The patient's presentation is suggestive of a congenital disorder characterized by excessive growth in the axial skeleton and underdevelopment of the limbs, which is a hallmark of a specific genetic condition.

**Why the Correct Answer is Right**
The diagnosis of Sotos syndrome is suspected based on the patient's physical examination findings, which include macrocephaly (large head), short limbs, broad fingers, a small face, and a long and narrow trunk. Sotos syndrome is caused by mutations in the NSD1 gene, which encodes a histone methyltransferase involved in the regulation of gene expression. This condition is characterized by accelerated growth during the first few years of life, followed by a slowing of growth velocity, and a characteristic facial appearance.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not address the specific diagnostic criteria for Sotos syndrome.

**Option B:** This option is incorrect as it does not provide a clear diagnostic approach for Sotos syndrome.

**Option C:** This option is incorrect as it may be relevant for other conditions, such as achondroplasia or hypochondroplasia, but not specifically for Sotos syndrome.

**Clinical Pearl / High-Yield Fact**
Sotos syndrome is a rare genetic disorder that should be considered in the differential diagnosis of children with macrocephaly and short limbs. The diagnosis can be confirmed by genetic testing for mutations in the NSD1 gene.

**Correct Answer:** C. Genetic testing for mutations in the NSD1 gene.