Rare diseases · Sign or symptom
Secondary microcephaly
HP:0005484
What it means
Head circumference which falls below 2 standard deviations below the mean for age and gender because of insufficient head growth after birth.
Rare diseases that can present with this33
Very common80–99%
6Common30–79%
17- 21q deletion syndrome
- Angelman syndrome due to a point mutation
- Atypical Rett syndrome
- Autosomal recessive cutis laxa type 2A
- Christianson syndrome
- COG2-CDG
- Early-onset progressive diffuse brain atrophy-microcephaly-muscle weakness-optic atrophy syndrome
- Infantile multisystem neurologic-endocrine-pancreatic disease
- MFF-related encephalopathy due to mitochondrial and peroxisomal fission defect
- Microcephaly-thin corpus callosum-intellectual disability syndrome
- Mowat-Wilson syndrome due to a ZEB2 point mutation
- Mowat-Wilson syndrome due to monosomy 2q22
- Ring chromosome 14 syndrome
- Rubinstein-Taybi syndrome due to 16p13.3 microdeletion
- Spastic tetraplegia-thin corpus callosum-progressive postnatal microcephaly syndrome
- Trigonocephaly-short stature-developmental delay syndrome
- X-linked intellectual disability, Schimke type
Sometimes5–29%
10- 8q24.3microdeletion syndrome
- Alacrimia-choreoathetosis-liver dysfunction syndrome
- Angelman syndrome due to paternal uniparental disomy of chromosome 15
- Early-onset epileptic encephalopathy and intellectual disability due to GRIN2A mutation
- Early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome
- Hypohidrosis-enamel hypoplasia-palmoplantar keratoderma-intellectual disability syndrome
- Lissencephaly type 1 due to doublecortin gene mutation
- Micrognathia-recurrent infections-behavioral abnormalities-mild intellectual disability syndrome
and 2 more in this range
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Acquired microcephaly · Deceleration of head growth · Development of small head that was not present at birth · Microcephaly, acquired · Microcephaly, postnatal · Postnatal deceleration of head circumference · Postnatal microcephaly
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.