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Research paper

Hypoglycemia due to PI3K/AKT/mTOR signaling pathway defects: two novel cases and review of the literature

Case series (2 novel cases) + literature review establishing that PI3K/AKT/mTOR pathway defects cause recurrent childhood hypoglycemia alongside the better-known overgrowth/macrocephaly/DD features. Patient 1 - PTEN germline missense, macrocephaly + recurrent hypoglycemia. Patient 2 - PPP2R5D missense (Houge-Janssens / autosomal dominant ID-35), macrocephaly + hypoglycemia. Most reported cases are low-insulin (GH-like) hypoglycemia; some hyperinsulinemic. Argues PI3K-AKT-mTOR defects should be added to the differential of pediatric hypoglycemia + macrocephaly.

Indexed context

Maines E, et al.

pi3k-akt-mtorptenppp2r5dhypoglycemiamacrocephalypediatric-endocrinologyovergrowth

Markdown path

content/research/papers/2021-maines-pi3k-akt-mtor-hypoglycemia.md

Findings

Case series (2 novel cases) + literature review establishing that PI3K/AKT/mTOR pathway defects cause recurrent childhood hypoglycemia alongside the better-known overgrowth/macrocephaly/DD features. Patient 1 - PTEN germline missense, macrocephaly + recurrent hypoglycemia. Patient 2 - PPP2R5D missense (Houge-Janssens / autosomal dominant ID-35), macrocephaly + hypoglycemia. Most reported cases are low-insulin (GH-like) hypoglycemia; some hyperinsulinemic. Argues PI3K-AKT-mTOR defects should be added to the differential of pediatric hypoglycemia + macrocephaly.

Why it may matter for Levi

Cross-cutting positive signal that mechanistically links the overgrowth theories (PI3K-AKT-mTOR, mosaic mTOR pathway) to the new hypothalamic-hpa-axis-contribution theory. If a PI3K-AKT-mTOR mosaic variant is identified in tissue, recurrent hypoglycemia is part of the expected phenotypic spectrum. Directly motivates the critical-sample workup at the next nocturnal awakening (diagnostic rank 18) and the structured pre-bedtime snack trial (treatment rank 12). Reframes the HPA branch as part of the overgrowth-theory phenotype rather than separate from it.

Paper text

Hypoglycemia due to PI3K/AKT/mTOR signaling pathway defects: two novel cases and review of the literature

Maines E, Franceschi R, Martinelli D, Soli F, Lepri F, Piccoli G, Soffiati M — Hormones (Athens) (2021). PMID 33876391 · doi:10.1007/s42000-021-00287-1

Findings summary

Case series (2 novel cases) + literature review establishing that defects in the PI3K/AKT/mTOR pathway cause recurrent hypoglycemia in childhood, alongside the better-known phenotypic features of overgrowth, macrocephaly, and developmental delay. Key points:

  • Patient 1: PTEN germline missense mutation (PTEN hamartoma tumor syndrome) with macrocephaly and recurrent hypoglycemia.
  • Patient 2: PPP2R5D missense mutation (Houge-Janssens syndrome / autosomal dominant mental retardation-35) with macrocephaly and hypoglycemia.
  • Biochemical profile of hypoglycemia varies — most reported cases are low-insulin (GH-like) hypoglycemia, but hyperinsulinemia has also been observed.
  • Authors argue PI3K/AKT/mTOR defects should be added to the differential diagnosis of pediatric hypoglycemia + macrocephaly.

Relevance to Levi

Directly relevant to the HPA theory and to the PI3K-AKT-mTOR theories simultaneously. Three transfers:

  1. If a PI3K-AKT-mTOR mosaic variant is identified in Levi (mosaic-sensitive tissue-based sequencing is on the diagnostics list), this paper establishes that recurrent hypoglycemia is part of the expected phenotypic spectrum. Levi has never had a fasting glucose drawn during a nocturnal awakening, so this remains untested.
  2. The 3 AM nocturnal awakening phenotype with stimmy hyperarousal and food-seeking is compatible with recurrent occult nocturnal hypoglycemia driven by a PI3K-AKT-mTOR defect, even though the happy/cuddly morning affect argues against severe counter-regulatory failure. A single critical-sample glucose during a nocturnal awakening would be a low-cost probe.
  3. Mechanistically connects the overgrowth theories (rank 1, 2 in differential) to the HPA/hypothalamic-endocrine theory. Rather than "HPA issues" being a separate theory that competes with the overgrowth theories, this paper reframes it as: if the overgrowth theory is right, endocrine dysregulation (including hypoglycemia and GH-axis abnormalities) is part of the expected phenotype, not separate from it.

Evidence strength: moderate for the specific PI3K-AKT-mTOR → hypoglycemia link (case reports + literature review, not a cohort); strong for the general claim that this pathway touches glucose homeostasis.

Provenance