{
  "url": "https://dantelabs.com/traits/decreased-head-circumference",
  "trait": {
    "bundleId": "2026.10.19-9814e911",
    "release": "2026-09-01",
    "slug": "decreased-head-circumference",
    "id": "HP:0040195",
    "name": "Decreased head circumference",
    "definition": "An abnormally reduced head circumference in a growing child. Head circumference is measured with a nonelastic tape and comprises the distance from above the eyebrows and ears and around the back of the head. The measured HC is then plotted on an appropriate growth chart. Microcephaly is defined as a head circumference (HC) that is great than two standard deviations below the mean of age- and gender-matched population based samples. Severe microcephaly is defined with an HC that is three standard deviations below the mean.",
    "synonyms": [],
    "systems": [
      {
        "slug": "abnormality-of-head-or-neck",
        "name": "Abnormality of head or neck",
        "url": "https://dantelabs.com/traits/abnormality-of-head-or-neck"
      },
      {
        "slug": "abnormality-of-the-musculoskeletal-system",
        "name": "Abnormality of the musculoskeletal system",
        "url": "https://dantelabs.com/traits/abnormality-of-the-musculoskeletal-system"
      }
    ],
    "broader": [
      {
        "slug": "abnormality-of-skull-size",
        "name": "Abnormality of skull size",
        "url": "https://dantelabs.com/traits/abnormality-of-skull-size"
      }
    ],
    "narrower": [
      {
        "slug": "microcephaly",
        "name": "Abnormally small head",
        "genes": 1316,
        "url": "https://dantelabs.com/traits/microcephaly"
      },
      {
        "slug": "mild-microcephaly",
        "name": "Mild microcephaly",
        "genes": 19,
        "url": "https://dantelabs.com/traits/mild-microcephaly"
      }
    ],
    "genes": [
      {
        "slug": "blm",
        "symbol": "BLM",
        "hgnc": "HGNC:1058",
        "name": "BLM RecQ like helicase",
        "frequency": "frequent",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/blm"
      },
      {
        "slug": "sin3a",
        "symbol": "SIN3A",
        "hgnc": "HGNC:19353",
        "name": "SIN3 transcription regulator family member A",
        "frequency": "frequent",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/sin3a"
      },
      {
        "slug": "sin3b",
        "symbol": "SIN3B",
        "hgnc": "HGNC:19354",
        "name": "SIN3 transcription regulator family member B",
        "frequency": "frequent",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/sin3b"
      },
      {
        "slug": "galc",
        "symbol": "GALC",
        "hgnc": "HGNC:4115",
        "name": "galactosylceramidase",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/galc"
      },
      {
        "slug": "igfals",
        "symbol": "IGFALS",
        "hgnc": "HGNC:5468",
        "name": "insulin like growth factor binding protein acid labile subunit",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/igfals"
      },
      {
        "slug": "pgap2",
        "symbol": "PGAP2",
        "hgnc": "HGNC:17893",
        "name": "post-GPI attachment to proteins 2",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pgap2"
      },
      {
        "slug": "pgap3",
        "symbol": "PGAP3",
        "hgnc": "HGNC:23719",
        "name": "post-GPI attachment to proteins phospholipase 3",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pgap3"
      },
      {
        "slug": "pigl",
        "symbol": "PIGL",
        "hgnc": "HGNC:8966",
        "name": "phosphatidylinositol glycan anchor biosynthesis class L",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigl"
      },
      {
        "slug": "pigo",
        "symbol": "PIGO",
        "hgnc": "HGNC:23215",
        "name": "phosphatidylinositol glycan anchor biosynthesis class O",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigo"
      },
      {
        "slug": "pigv",
        "symbol": "PIGV",
        "hgnc": "HGNC:26031",
        "name": "phosphatidylinositol glycan anchor biosynthesis class V",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigv"
      },
      {
        "slug": "pigw",
        "symbol": "PIGW",
        "hgnc": "HGNC:23213",
        "name": "phosphatidylinositol glycan anchor biosynthesis class W",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigw"
      },
      {
        "slug": "pigy",
        "symbol": "PIGY",
        "hgnc": "HGNC:28213",
        "name": "phosphatidylinositol glycan anchor biosynthesis class Y",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigy"
      },
      {
        "slug": "psap",
        "symbol": "PSAP",
        "hgnc": "HGNC:9498",
        "name": "prosaposin",
        "frequency": "occasional",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/psap"
      },
      {
        "slug": "cdk10",
        "symbol": "CDK10",
        "hgnc": "HGNC:1770",
        "name": "cyclin dependent kinase 10",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/cdk10"
      },
      {
        "slug": "pigp",
        "symbol": "PIGP",
        "hgnc": "HGNC:3046",
        "name": "phosphatidylinositol glycan anchor biosynthesis class P",
        "diseases": 1,
        "url": "https://dantelabs.com/genes/pigp"
      }
    ]
  }
}