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An X-linked recessive syndrome caused by loss-of-function mutation(s) in IGSF1, encoding immunoglobulin superfamily member 1. This condition can result in central hypothyroidism, macroorchidism, delayed puberty, and variable prolactin deficiency.
Features include always present findings: Inappropriately normal thyroid-stimulating hormone level and Hypothyroidism; and common findings: Reduced circulating prolactin concentration. 5 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Hormones | 2 | Inappropriately normal thyroid-stimulating hormone level, Hypothyroidism |
IGSF1 encodes immunoglobulin superfamily member 1 (1,336 aa). Seems to be a coreceptor in inhibin signaling, but seems not to be a high-affinity inhibin receptor. Antagonizes activin A signaling in the presence or absence of inhibin B. Highest expression in Pituitary (185.6 TPM) and Brain Hypothalamus (14.0 TPM).
X-linked central congenital hypothyroidism with late-onset testicular enlargement is associated with mutations in the IGSF1 gene on chromosome X.
IGSF1 is classified as a druggable target with score 0.0.
Genetic testing for IGSF1 is available. Testing is considered confirmatory for diagnosis.
Phenotype severity distribution: 2 always present features, 1 common feature.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for X-linked central congenital hypothyroidism with late-onset testicular enlargement.
4 publications have been identified in PubMed for X-linked central congenital hypothyroidism with late-onset testicular enlargement. Research spans Review / Meta-Analysis (50%), Case Report / Case Series (25%), and Epidemiology / Natural History (25%).
Ruta R (2025). [PMID: 41462822](https://pubmed.ncbi.nlm.nih.gov/41462822/). *Children (Basel, Switzerland)*. [Case Report / Case Series]
Bonomi M (2025). [PMID: 39126560](https://pubmed.ncbi.nlm.nih.gov/39126560/). *J Endocrinol Invest*. [Review / Meta-Analysis]
Tolmacheva EN (2025). [PMID: 39985054](https://pubmed.ncbi.nlm.nih.gov/39985054/). *Mol Cytogenet*. [Epidemiology / Natural History]
Shimon I (2024). [PMID: 39356415](https://pubmed.ncbi.nlm.nih.gov/39356415/). *Reviews in endocrine & metabolic disorders*. [Review / Meta-Analysis]
Data assembled from 6 of 12 sources · Last updated Sep 20, 2026, 9:51 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center
Common questions about X-linked central congenital hypothyroidism with late-onset testicular enlargement