X-LAG: How did they grow so tall?

Area of Science:

• Genetics
• Endocrinology
• Pediatrics

Background:

• X-linked acrogigantism (XLAG) is a recently identified genetic syndrome.
• It is characterized by microduplications at Xq26.3, specifically involving the GPR101 gene.

Observation:

• XLAG presents in early childhood, typically before age 5, distinguishing it from other forms of pituitary gigantism.
• Affected individuals exhibit mixed growth hormone (GH) and prolactin-positive pituitary adenomas or hyperplasia.
• Patients present with markedly elevated GH, IGF-1, and prolactin levels.

Findings:

• The syndrome results in significant GH hypersecretion, leading to severe gigantism with advanced age-specific height Z-scores.
• Early-onset and pronounced GH excess contribute to extreme final adult height if untreated.
• The clinical trajectory of XLAG mirrors that of historically documented cases of extreme human gigantism.

Implications:

• Understanding XLAG's genetic basis (GPR101 microduplications) is crucial for early diagnosis and intervention.
• Prompt treatment in childhood is essential to mitigate severe growth acceleration and extreme adult height.
• XLAG expands the spectrum of pituitary gigantism, highlighting the role of GPR101 in pituitary development and function.