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    "story_id": "mp-2026-07-17-010",
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    "headline": "A Second X Copy Protects the Developing Heart",
    "slug": "a-second-x-copy-protects-the-developing-heart",
    "dek": "Deleting DDX3X was lethal to female mouse embryos while males survived, exposing a sex-specific translation safeguard.",
    "summary": "Deleting DDX3X was lethal to female mouse embryos while males survived, exposing a sex-specific translation safeguard.",
    "body_text": "A UNC-led mouse study found that deleting X-linked DDX3X from developing heart tissue killed female embryos while males partly compensated with a Y-linked gene. DDX3X helps translate structured cardiac messages. The mechanism is established in mice, not a diagnosed human syndrome.",
    "why_it_matters": "Deleting DDX3X was lethal to female mouse embryos while males survived, exposing a sex-specific translation safeguard.",
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    "first_published_at": "2026-07-17T09:00:00.000-04:00",
    "modified_at": "2026-07-17T14:34:04.943-04:00",
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        "qualification": "The mechanism is established in mice, not a diagnosed human syndrome."
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    "tags": [
      "DDX3X",
      "heart development",
      "translation"
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    {
      "source_id": "source-2026-07-17-010",
      "title": "UNC Health via Newswise: Female-heart genetic safeguard",
      "publisher": "UNC Health via Newswise",
      "url": "https://www.newswise.com/articles/a-genetic-safeguard-that-protects-the-female-heart-and-what-happens-when-it-s-lost",
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      "published_at": "2026-07-16T18:45:00.000-04:00",
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  "cite_this_report": {
    "title": "A Second X Copy Protects the Developing Heart",
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