Rare diseases · Sign or symptom
Sparse scalp hair
Reduced amount of scalp hair
HP:0002209
What it means
Decreased number of hairs per unit area of skin of the scalp.
Hypotrichosis should not be used as a synonym as, formally, it means underdevelopment of the hair. No normal values for number of hairs per unit area exist.
Rare diseases that can present with this61
Very common80–99%
29- Alopecia-epilepsy-pyorrhea-intellectual disability syndrome
- Alopecia-intellectual disability syndrome
- Autosomal dominant palmoplantar keratoderma and congenital alopecia
- Cleft lip/palate-deafness-sacral lipoma syndrome
- Craniofacial dysplasia-short stature-ectodermal anomalies-intellectual disability syndrome
- Dermoodontodysplasia
- EEM syndrome
- Epidermolysis bullosa simplex with anodontia/hypodontia
- Graham Little-Piccardi-Lassueur syndrome
- Hidrotic ectodermal dysplasia, Christianson-Fourie type
- Hidrotic ectodermal dysplasia, Halal type
- Hypohidrotic ectodermal dysplasia
- Hypohidrotic ectodermal dysplasia-hypothyroidism-ciliary dyskinesia syndrome
- Hypotrichosis-lymphedema-telangiectasia-renal defect syndrome
- Hypotrichosis simplex
- Hypotrichosis with juvenile macular degeneration
- Linear verrucous nevus syndrome
- Marie Unna hereditary hypotrichosis
- Neonatal ichthyosis-sclerosing cholangitis syndrome
- Netherton syndrome
- Noonan syndrome-like disorder with loose anagen hair
- RIN2 syndrome
- Syringocystadenoma papilliferum
- Trichodermodysplasia-dental alterations syndrome
- Trichodysplasia-xeroderma syndrome
- Trichorhinophalangeal syndrome type 2
- Vogt-Koyanagi-Harada disease
- Werner syndrome
- Wiedemann-Rautenstrauch syndrome
Common30–79%
20- 2q37microdeletion syndrome
- ADULT syndrome
- Aymé-Gripp syndrome
- B4GALT7-related spondylodysplastic Ehlers-Danlos syndrome
- Basel-Vanagaite-Smirin-Yosef syndrome
- Bazex-Dupré-Christol syndrome
- Coffin-Siris syndrome
- Dubowitz syndrome
- Genitopatellar syndrome
- Homocystinuria due to cystathionine beta-synthase deficiency
- Hoyeraal-Hreidarsson syndrome
- Hypotrichosis simplex of the scalp
- Naxos disease
- Oculocerebrorenal syndrome of Lowe
- Osteopenia-intellectual disability-sparse hair syndrome
- Paraplegia-intellectual disability-hyperkeratosis syndrome
- Proliferating trichilemmal cyst
- Scalp defects-postaxial polydactyly syndrome
- Seckel syndrome
- Yunis-Varon syndrome
Sometimes5–29%
10- Cushing disease
- Cushing syndrome due to ectopic ACTH secretion
- Global developmental delay-alopecia-macrocephaly-facial dysmorphism-structural brain anomalies syndrome
- Goldberg-Shprintzen megacolon syndrome
- Hidrotic ectodermal dysplasia
- Palatal anomalies-widely spaced teeth-facial dysmorphism-developmental delay syndrome
- Pseudoaminopterin syndrome
- Ramos-Arroyo 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: Decreased number of scalp follicles · Hypotrichosis on scalp · Reduced/lack of hair on scalp · Reduction in the number of scalp follicles · Scalp hypotrichosis · Thin scalp hair · Thinning scalp hair
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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.