2. Achondroplasia.mp4

Laron Syndrome (Dwarfism).mp4

This case of short stature (100-120 cm) might be due to multiple causes:

• GHRH (Growth Hormone Releasing Hormone) deficiency.
• GH (Growth Hormone) deficiency.
• Deficient local secretion of IGF-1 by chondrocytes.
• GH insensitivity: This is due to a mutation of the GH receptor gene which results in defective growth hormone receptors. This can lead to a decrease in linear growth, a condition known as Laron dwarfism. It is characterized by high serum levels of growth hormone in the presence of low IGF-1 levels. Although the size of the trunk and all extremities is smaller, they are well-proportioned (span equals height, vertex to symphysis equals symphysis to heel). Individuals with this condition are mentally and sexually normal.

Treatment includes the use of human growth hormone synthesized by E. Coli bacteria through recombinant DNA technology.

• Pituitary dwarfism is associated with hypogonadism and involves a deficiency of gonadotrophic hormones in addition to the growth hormone (GH).

The differential diagnosis includes:

Achondroplastic dwarf:

• This is the most common clinical form of dwarfism.
• It is caused by an autosomal dominant mutation of the gene for the fibroblast growth factor receptor 3 (FGFR 3).
• While the trunk (head, neck, chest, and pelvis) is normal, the limbs are short, resulting in a disproportion between limbs and trunk.

Thyroid dwarf (cretin):

• This form of dwarfism is due to a deficiency of thyroid hormones during infancy.
• Physically, growth is retarded.
• There is a disproportion in the size of the viscera (big tongue, liver, abdomen) in relation to skeletal size.
• Individuals with this condition often experience mental and sexual retardation.