Rare diseases · Sign or symptom
Plagiocephaly
Flat head syndrome
HP:0001357
What it means
Asymmetric head shape, which is usually a combination of unilateral occipital flattening with ipsilateral frontal prominence, leading to rhomboid cranial shape.
Plagiocephaly may affect the posterior skull alone. With plagiocephaly, one can see a combination of unilateral occipital flattening with ipsilateral frontal prominence, leading to rhomboid cranial shape or asymmetry of the posterior skull alone.
Rare diseases that can present with this61
Very common80–99%
6Common30–79%
25- 6q25.2q25.3microdeletion syndrome
- 9q33.3q34.11microdeletion syndrome
- Anophthalmia-megalocornea-cardiopathy-skeletal anomalies syndrome
- Auricular abnormalities-cleft lip with or without cleft palate-ocular abnormalities syndrome
- Aymé-Gripp syndrome
- BRESEK syndrome
- Corpus callosum agenesis-macrocephaly-hypertelorism syndrome
- Craniofrontonasal dysplasia
- Craniofrontonasal dysplasia-Poland anomaly syndrome
- FG syndrome type 1
- Houge-Janssens syndrome type 2
- Hypotonia-speech impairment-severe cognitive delay syndrome
- Intellectual disability-cataracts-calcified pinnae-myopathy syndrome
- KAT6-related intellectual disability-craniofacial anomalies-cardiac defects syndrome
- Linear nevus sebaceus syndrome
- Microgastria-limb reduction defect syndrome
- Muenke syndrome
- Neurofaciodigitorenal syndrome
- Pentasomy X syndrome
- PRUNE1-related neurological syndrome
- Saethre-Chotzen syndrome
- Severe intellectual disability-epilepsy-anal anomalies-distal phalangeal hypoplasia
- Spastic paraplegia-intellectual disability-nystagmus-obesity syndrome
- Trisomy 20p syndrome
- X-linked intellectual disability-plagiocephaly syndrome
Sometimes5–29%
27- 6q terminal deletion syndrome
- 7q31microdeletion syndrome
- Aicardi-Goutières syndrome
- Aicardi syndrome
- Atelosteogenesis type II
- B3GALT6-related spondylodysplastic Ehlers-Danlos syndrome
- Cognitive impairment-coarse facies-heart defects-obesity-pulmonary involvement-short stature-skeletal dysplasia syndrome
- Congenital fibrosis of extraocular muscles
and 19 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: Asymmetry of the posterior cranium · Asymmetry of the posterior head · Asymmetry of the posterior skull · Deformational plagiocephaly · Flat head · Flattening of cranial vault · Flattening of cranium · Flattening of head
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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.