Rare diseases · Sign or symptom
Decreased testicular size
Small testes
HP:0008734
What it means
Reduced volume of the testicle (the male gonad).
Rare diseases that can present with this80
Very common80–99%
37- 46,XX testicular difference of sex development
- 46,XY difference of sex development-adrenal insufficiency due to CYP11A1 deficiency
- 46,XY partial gonadal dysgenesis
- 48,XXXY syndrome
- 48,XXYY syndrome
- 49,XXXXY syndrome
- 49,XXXYY syndrome
- 49,XYYYY syndrome
- Borjeson-Forssman-Lehmann syndrome
- Chromosome Y microdeletion syndrome
- Congenital fibrinogen deficiency
- Congenital muscular dystrophy-infantile cataract-hypogonadism syndrome
- H syndrome
- Hypogonadotropic hypogonadism-severe microcephaly-sensorineural hearing loss-dysmorphism syndrome
- Inherited isolated adrenal insufficiency due to partial CYP11A1 deficiency
- Intellectual disability-dysmorphism-hypogonadism-diabetes mellitus syndrome
- Intrauterine growth restriction-short stature-early adult-onset diabetes syndrome
- Isochromosomy Yp syndrome
- Isochromosomy Yq syndrome
- Isolated follicle stimulating hormone deficiency
- Kallmann syndrome
- Male hypergonadotropic hypogonadism-intellectual disability-skeletal anomalies syndrome
- Male infertility with azoospermia or oligozoospermia due to single gene mutation
- Male infertility with teratozoospermia due to single gene mutation
- Neonatal Marfan syndrome
- Normosmic congenital hypogonadotropic hypogonadism
- Obesity due to congenital leptin deficiency
- Obesity due to leptin receptor gene deficiency
- Orofaciodigital syndrome type 4
- Paternal uniparental disomy of chromosome X syndrome
- Retinitis pigmentosa-intellectual disability-deafness-hypogonadism syndrome
- Testicular regression syndrome
- Woodhouse-Sakati syndrome
- X-linked intellectual disability, Abidi type
- X-linked intellectual disability, Cilliers type
- X-linked intellectual disability, Van Esch type
- Xq27.3q28duplication syndrome
Common30–79%
24- 46,XY difference of sex development due to isolated 17,20-lyase deficiency
- Autosomal dominant Kenny-Caffey syndrome
- BRESEK syndrome
- Combined pituitary hormone deficiencies, genetic forms
- Intellectual disability-balding-patella luxation-acromicria syndrome
- Kallmann syndrome-heart disease syndrome
- Keppen-Lubinsky syndrome
- Non-acquired panhypopituitarism
- Polyendocrine-polyneuropathy syndrome
- Prader-Willi syndrome
- Prader-Willi syndrome due to maternal uniparental disomy of chromosome 15
- Prader-Willi syndrome due to paternal 15q11q13 deletion
- Prader-Willi syndrome due to paternal deletion of 15q11q13 type 1
- Prader-Willi syndrome due to paternal deletion of 15q11q13 type 2
- Prune belly syndrome
- Renpenning syndrome
- SATB2-associated syndrome due to a chromosomal rearrangement
- Schaaf-Yang syndrome
- Silver-Russell syndrome
- SIM1-related Prader-Willi-like syndrome
- X-linked adrenal hypoplasia congenita
- X-linked intellectual disability, Cabezas type
- X-linked intellectual disability, Siderius type
- X-linked intellectual disability, Sutherland-Haan type
Sometimes5–29%
18- 2p15p16.1microdeletion syndrome
- 2q32q33deletion syndrome
- Alström syndrome
- Aromatase excess syndrome
- Autosomal recessive spastic paraplegia type 46
- Bardet-Biedl syndrome
- Classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency
- Congenital adrenal hyperplasia due to 3-beta-hydroxysteroid dehydrogenase deficiency
and 10 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 testicular volume · Hypoplastic testes · Reduced testicular volume · Small testis · Testicular hypoplasia
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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.