The genetic causes of growth hormone deficiency primarily involve mutations in specific genes, leading to various types of the condition. Isolated growth hormone deficiency (IGHD) is most commonly linked to these genetic mutations.
Genes Involved in Growth Hormone Deficiency
Mutations in the following genes can cause growth hormone deficiency:
- GH1 gene: Mutations in the GH1 gene are responsible for IGHD type IA and type II. This gene provides instructions for making growth hormone.
- GHRHR gene: Mutations in the GHRHR gene cause IGHD type IB. This gene provides instructions for making the growth hormone-releasing hormone receptor.
- BTK gene: Mutations in the BTK gene cause IGHD type III.
Types of Isolated Growth Hormone Deficiency (IGHD) and Associated Genes
The specific genetic cause often corresponds to the type of IGHD a person has.
| Type of IGHD | Gene(s) Involved | Description |
|---|---|---|
| IA | GH1 | Complete or near-complete absence of growth hormone. |
| IB | GH1 or GHRHR | Low, but detectable, levels of growth hormone. |
| II | GH1 | Variable growth hormone levels; can be autosomal dominant or autosomal recessive. |
| III | BTK | Linked to X-linked agammaglobulinemia (XLA), affecting growth hormone. |
Understanding the Mutations
These mutations disrupt the normal production, release, or signaling of growth hormone, leading to insufficient levels needed for proper growth and development. The severity of the deficiency can vary depending on the specific mutation and its effect on the gene's function.
