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Growth hormone deficiency has no single definite cause. It can be caused by mutations of specific genes, damage to the pituitary gland, Turner's syndrome, poor nutrition, [27] or even stress (leading to psychogenic dwarfism). Laron syndrome (growth hormone insensitivity) is another cause. Those with growth hormone issues tend to be proportionate.
Laron syndrome (LS), also known as growth hormone insensitivity or growth hormone receptor deficiency (GHRD), is an autosomal recessive disorder characterized by a lack of insulin-like growth factor 1 (IGF-1; somatomedin-C) production in response to growth hormone (GH; hGH; somatotropin). [6]
Achondroplasia in children is the most common form of dwarfism; it accounts for about 70% of all cases of dwarfism. [1] Achondroplasia falls into the category of “disproportionate dwarfism”. It is linked to a mutation in the fibroblast growth factor receptor-3. More than 250,000 people in the world are diagnosed with achondroplasia.
Achondroplasia is a genetic disorder with an autosomal dominant pattern of inheritance whose primary feature is dwarfism. [3] It is the most common cause of dwarfism [4] and affects about 1 in 27,500 people. [3] In those with the condition, the arms and legs are short, while the torso is typically of normal length. [3]
Shortened stature can result from growth hormone deficiency, starvation, portal systemic shunts, renal disease, hypothyroidism diabetes mellitus and other conditions. Any of these conditions can be established in a population through genetic engineering, selective breeding, or insular dwarfism, or some combination of the above.
Growth hormone deficiency in childhood commonly has no identifiable cause (idiopathic), and adult-onset GHD is commonly due to pituitary tumours and their treatment or to cranial irradiation. [9] A more complete list of causes includes: mutations of specific genes (e.g., GHRHR, GH1)
It is believed to be caused by defects of genes on chromosome 3 and 18. One form of Seckel syndrome can be caused by mutation in the gene encoding the ataxia telangiectasia and Rad3-related protein which maps to chromosome 3q22.1–q24. This gene is central in the cell's DNA damage response and repair mechanism. Types include: [6]
Dwarfism may also be caused by malnutrition or other hormonal deficiencies, such as insufficient growth hormone secretion, hypopituitarism, decreased secretion of growth hormone-releasing hormone, deficient growth hormone receptor activity and downstream causes, such as insulin-like growth factor 1 (IGF-1) deficiency. [14]