Rare diseases · Sign or symptom
Macrocephaly
Increased size of skull
HP:0000256
What it means
Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.
Macrocephaly can be due to hydrocephalus (increased CFSF), megalencephaly (increased brain volume) or thickening of the skull. Head circumference is measured from just above the glabella (the most prominent point on the frontal bone above the root of the nose) to the most posterior prominent point of the occipital bone using a tape measure. Some standard charts are organized by centiles [Hall et al. [2007]], others by standard deviations [Farkas, [1981]]. It is important to add an indication of how far above the normal standard the head circumference is if an accurate assessment of this can be made. Macrocephaly is an absolute term. The term relative macrocephaly can be used when the head size centile exceeds the centile for height, for example, head size at the 75th centile with height at the 5th centile for age and sex.
Rare diseases that can present with this231
Very common80–99%
77- 10q22.3q23.3microdeletion syndrome
- 19p13.13microdeletion syndrome
- 3q13microdeletion syndrome
- 7p22.1microduplication syndrome
- Achondrogenesis
- Achondrogenesis type 1A
- Achondrogenesis type 1B
- Acrocallosal syndrome
- Albers-Schönberg osteopetrosis
- Alexander disease
- Atkin-Flaitz syndrome
- Autosomal recessive malignant osteopetrosis
- B4GALT7-related spondylodysplastic Ehlers-Danlos syndrome
- Bannayan-Riley-Ruvalcaba syndrome
- Brachydactyly-elbow wrist dysplasia syndrome
- Campomelic dysplasia
- Carpenter syndrome
- Congenital-onset Steinert myotonic dystrophy
- Corpus callosum agenesis-intellectual disability-coloboma-micrognathia syndrome
- Corpus callosum agenesis-macrocephaly-hypertelorism syndrome
- Costello syndrome
- Craniodiaphyseal dysplasia
- Craniometadiaphyseal dysplasia, wormian bone type
- Diastrophic dysplasia
- Dysosteosclerosis
- Early-onset parkinsonism-intellectual disability syndrome
- Ectodermal dysplasia-intellectual disability-central nervous system malformation syndrome
- Facial dysmorphism-macrocephaly-myopia-Dandy-Walker malformation syndrome
- Familial scaphocephaly syndrome, McGillivray type
- Frontal encephalocele
- Gingival fibromatosis-facial dysmorphism syndrome
- Greig cephalopolysyndactyly syndrome
- Houge-Janssens syndrome type 1
- Infantile systemic hyalinosis
- Intellectual disability-seizures-macrocephaly-obesity syndrome
- Isolated Dandy-Walker malformation
- Isolated megalencephaly
- Isolated rhombencephalosynapsis
- Juvenile Paget disease
- Lenz-Majewski hyperostotic dysplasia
- Lhermitte-Duclos disease
- Linear verrucous nevus syndrome
- Lujan-Fryns syndrome
- Macrocephaly-intellectual disability-autism syndrome
- Macrocephaly-intellectual disability-neurodevelopmental disorder-small thorax syndrome
- Macrocephaly-spastic paraplegia-dysmorphism syndrome
- Megalencephaly-capillary malformation-polymicrogyria syndrome
- Megalencephaly-polymicrogyria-postaxial polydactyly-hydrocephalus syndrome
- Monosomy 9q22.3 syndrome
- Mucopolysaccharidosis type 2
- Mulibrey nanism
- Multiple epiphyseal dysplasia-macrocephaly-facial dysmorphism syndrome
- Non-syndromic bilambdoid and sagittal craniosynostosis
- Opsismodysplasia
- Osteogenesis imperfecta
- Osteosclerosis-developmental delay-craniosynostosis syndrome
- Overgrowth-macrocephaly-facial dysmorphism syndrome
- Perlman syndrome
- Polyhydramnios-megalencephaly-symptomatic epilepsy syndrome
- Radioulnar synostosis-developmental delay-hypotonia syndrome
- Rapid-onset childhood obesity-hypothalamic dysfunction-hypoventilation-autonomic dysregulation syndrome
- Sandhoff disease
- Schneckenbecken dysplasia
- Severe Canavan disease
- Simpson-Golabi-Behmel syndrome
- Tatton-Brown-Rahman syndrome
- Tetrasomy 5p syndrome
- Thanatophoric dysplasia
- Thanatophoric dysplasia type 1
- Thanatophoric dysplasia type 2
- Thin ribs-tubular bones-dysmorphism syndrome
- Trisomy 5p syndrome
- Unilateral ocular duplication
- Weaver syndrome
- X-linked epilepsy-learning disabilities-behavior disorders syndrome
- X-linked intellectual disability-Dandy-Walker malformation-basal ganglia disease-seizures syndrome
- X-linked intellectual disability-macrocephaly-macroorchidism syndrome
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: Big calvaria · Big cranium · Big head · Big skull · Increased size of cranium · Increased size of head · Large calvaria · Large cranium
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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.