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MAP3K1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MAP3K1 gene

The MAP3K1 gene produces a protein that regulates signaling pathways involved in various bodily processes, including the determination of sex characteristics before birth.

Normal Function

The MAP3K1 gene provides instructions for making a protein that helps regulate signaling pathways that control various processes in the body, including the processes of determining sex characteristics before birth. The MAP3K1 protein attaches (binds) to other molecules called RHOA, MAP3K4, FRAT1, and AXIN1. The binding of MAP3K1 to these molecules, which are called cofactors, helps MAP3K1 control the activity of the signaling pathways.

Health Conditions Related to Genetic Changes

Swyer syndrome

Variants (also called mutations) in the MAP3K1 gene are thought to account for up to 18 percent of cases of Swyer syndrome, also known as 46,XY complete gonadal dysgenesis or 46,XY pure gonadal dysgenesis. Swyer syndrome is a condition that affects sex development.

The MAP3K1 gene variants that cause Swyer syndrome result in production of MAP3K1 proteins that attach to cofactors more readily than usual. Enhanced binding reduces signaling that leads to male-typical sex development and increases signaling that leads to female-typical sex development. As a result, affected individuals with a 46,XY karyotype will not develop male gonads (testes) but will develop female reproductive structures (a uterus and fallopian tubes).

Other disorders

MAP3K1 gene variants have also been identified in people with 46,XY disorder of sex development, which is also known as partial gonadal dysgenesis. These variants likely have similar but less severe effects on signaling pathways involved in sex development than those that cause Swyer syndrome. Affected individuals may have external genitalia that do not look clearly male or clearly female or other abnormalities of the genitals and reproductive organs.

Other Names for This Gene

  • M3K1_HUMAN
  • MAP/ERK kinase kinase 1
  • MAPK/ERK kinase kinase 1
  • MAPKKK1
  • MEK kinase 1
  • MEKK
  • MEKK 1
  • MEKK1
  • mitogen-activated protein kinase kinase kinase 1, E3 ubiquitin protein ligase
  • SRXY6

Frequently Asked Questions

In most MAP3K1‑related cases, the testes fail to develop, so endogenous sperm production is absent. Fertility therefore relies on donor gametes (egg or sperm) combined with assisted reproductive techniques. If any functional gonadal tissue remains, a fertility specialist may assess sperm retrieval options, but this is rarely successful in MAP3K1‑associated gonadal dysgenesis.
Yes. MAP3K1 mutations are typically autosomal dominant with variable expressivity, so first‑degree relatives have a 50 % chance of carrying the same variant. Offering predictive testing allows early identification of at‑risk individuals, informs decisions about sex development monitoring, and guides reproductive counseling.
Diagnosis usually begins with a detailed clinical evaluation and karyotype analysis (46,XY or 46,XX). If the karyotype is 46,XY and the phenotype is atypical, clinicians often order a targeted next‑generation sequencing panel for disorders of sex development, which includes MAP3K1. Confirmation is achieved by identifying a pathogenic or likely pathogenic variant in the gene, sometimes followed by segregation testing of parents to determine inheritance.
Management focuses on hormone replacement therapy (HRT) to induce and maintain secondary female sexual characteristics and to protect bone health. Because the gonads are streak (non‑functional), prophylactic removal is recommended to eliminate the risk of gonadal tumor development. After HRT, many patients can use assisted reproductive technologies (e.g., donor‑egg IVF) if they wish to become pregnant.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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