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#alcohol exposure

2 public questions tagged with this topic.

Teratogens

Alcohol exposure at gastrulation leads to defects in:

Gastrulation stage corresponds to formation of primitive streak and ingression of mesoderm, around third week in humans. Ethanol exposure at this period preferentially kills anterior prechordal mesoderm and disrupts Sonic hedgehog signaling essential for midline facial prominence growth. Progenitors of frontonasal process, mediating midface formation, and forebrain neuroectoderm are depleted leading to characteristic fetal alcohol face: short palpebral fissures, smooth philtrum, thin upper lip and microcephaly with holoprosencephaly-like brain midline defects. Heart and limb less affected at this very early stage. Hence gastrulation alcohol insult leads to face and brain predominant anomalies reflecting midline pattern failure.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 20: Alcohol gastrulation face brain defects.

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Teratogens

Alcohol exposure blocks the adhesive function of:

L1 cell adhesion molecule mediates calcium-independent homophilic binding through immunoglobulin domains promoting cell-cell adhesion critical for neural crest migration and axon guidance. Ethanol at concentrations achieved after binge drinking interacts with extracellular domain at Gly-122 pocket, converting L1 to non-adhesive conformation, blocking homophilic binding and downstream Erk signaling required for growth cone motility. Other adhesion molecules like N-CAM or integrins are resistant at those doses, showing selectivity. Impaired L1 function replicates migration deficits seen in L1 mutation disorders such as hydrocephalus and contributes to fetal alcohol facial and brain anomalies resulting from defective cell adhesion.

Ref: Gilbert, Developmental Biology, 12th ed., Chapter 20: Alcohol blocks L1 adhesion molecule.

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