Mosaic Disorders of the PI3K/PTEN/AKT/TSC/mTORC1 Signaling Pathway

Area of Science:

• Genetics
• Molecular Biology
• Developmental Biology

Background:

• Somatic mutations in the PI3K/PTEN/AKT/TSC/mTORC1 pathway are linked to various overgrowth syndromes, hamartomas, and tumors.
• Mosaicism, where genetic mutations occur after fertilization, underlies conditions such as Proteus syndrome, PIK3CA-Related Overgrowth Spectrum, PTEN hamartoma tumor syndrome, and tuberous sclerosis complex.

Purpose of the Study:

• To summarize the genetic basis and clinical manifestations of mosaic overgrowth disorders linked to the PI3K/PTEN/AKT/TSC/mTORC1 pathway.
• To highlight the role of embryological timing and tissue type in disease presentation.
• To emphasize the diagnostic utility of deep sequencing and the therapeutic potential of pathway-targeted drugs.

Main Methods:

• Review of existing literature on somatic mutations in the PI3K/PTEN/AKT/TSC/mTORC1 pathway.
• Analysis of genotype-phenotype correlations in mosaic overgrowth syndromes.
• Discussion of diagnostic approaches including deep sequencing.
• Overview of current therapeutic strategies and clinical trials.

Main Results:

• Activating mutations in AKT1 or PIK3CA lead to Proteus syndrome and PIK3CA-Related Overgrowth Spectrum.
• Postzygotic mutations in PTEN or TSC1/TSC2 cause mosaic PTEN hamartoma tumor syndrome and tuberous sclerosis complex, respectively.
• Disease phenotypes are influenced by the timing of mutation occurrence during embryonic development and the specific tissues affected.

Conclusions:

• Somatic mosaic mutations in the PI3K/PTEN/AKT/TSC/mTORC1 pathway are key drivers of diverse overgrowth syndromes.
• Deep sequencing of affected tissues is a valuable diagnostic tool for these conditions.
• Targeted therapies inhibiting mTORC1 and other pathway components show promise for clinical treatment.