Persistent Müllerian duct syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Persistent Müllerian duct syndrome is a disorder of sexual development that affects males. Males with this disorder have normal male reproductive organs, though they also have a uterus and fallopian tubes, which are female reproductive organs. The uterus and fallopian tubes are derived from a structure called the Müllerian duct during development of the fetus. The Müllerian duct usually breaks down during early development in males, but it is retained in those with persistent Müllerian duct syndrome. Affected individuals have the normal chromosomes of a male (46,XY) and normal external male genitalia.

The first noted signs and symptoms in males with persistent Müllerian duct syndrome are usually undescended testes (cryptorchidism) or soft out-pouchings in the lower abdomen (inguinal hernias). The uterus and fallopian tubes are typically discovered when surgery is performed to treat these conditions.

The testes and female reproductive organs can be located in unusual positions in persistent Müllerian duct syndrome. Occasionally, both testes are undescended (bilateral cryptorchidism) and the uterus is in the pelvis. More often, one testis has descended into the scrotum normally, and one has not. Sometimes, the descended testis pulls the fallopian tube and uterus into the track through which it has descended. This creates a condition called hernia uteri inguinalis, a form of inguinal hernia. In other cases, the undescended testis from the other side of the body is also pulled into the same track, forming an inguinal hernia. This condition, called transverse testicular ectopia, is common in people with persistent Müllerian duct syndrome.

Other effects of persistent Müllerian duct syndrome may include the inability to father children (infertility) or blood in the semen (hematospermia). Also, the undescended testes may break down (degenerate) or develop cancer if left untreated.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Most people with persistent Müllerian duct syndrome have mutations in the AMH gene or the AMHR2 gene. The AMH gene provides instructions for making a protein called anti-Müllerian hormone (AMH). The AMHR2 gene provides instructions for making a protein called AMH receptor type 2.

The AMH protein and AMH receptor type 2 protein are involved in male sex differentiation. All fetuses develop the Müllerian duct, the precursor to female reproductive organs. During development of a male fetus, these two proteins work together to induce breakdown (regression) of the Müllerian duct. Mutations in the AMH and AMHR2 genes lead to nonfunctional proteins that cannot signal for regression of the Müllerian duct. As a result of these mutations, the Müllerian duct persists and goes on to form a uterus and fallopian tubes.

Approximately 45 percent of cases of persistent Müllerian duct syndrome are caused by mutations in the AMH gene and are called persistent Müllerian duct syndrome type 1. Approximately 40 percent of cases are caused by mutations in the AMHR2 gene and are called persistent Müllerian duct syndrome type 2. In the remaining 15 percent of cases, no mutations in the AMH and AMHR2 genes have been identified, and the genes involved in causing the condition are unknown.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. However, persistent Müllerian duct syndrome affects only males. Females with two mutated copies of the gene do not show signs and symptoms of the condition.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Persistent Müllerian duct syndrome is a rare disorder; however, the prevalence of the condition is unknown.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Cryptorchidism · Very frequent (99-80%)

Testis in inguinal canal. That is, absence of one or both testes from the scrotum owing to failure of the testis or testes to descend through the inguinal canal to the scrotum.

Inguinal hernia · Frequent (79-30%)

Protrusion of the contents of the abdominal cavity through the inguinal canal.

Male pseudohermaphroditism · Frequent (79-30%)

Hermaphroditism refers to a discrepancy between the morphology of the gonads and that of the external genitalia. In male pseudohermaphroditism, the genotype is male (XY) and the external genitalia are imcompletely virilized, ambiguous, or complete female. If gonads are present, they are testes.

Which doctor should you see?

The suggested department for discussing Persistent Müllerian duct syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

Where the source describes treatments, these are an overview of possible care, not a prescription for an individual. Ask which option applies to the confirmed diagnosis, what benefit is expected, what adverse effects to watch for and how progress will be assessed. Availability, approvals and local practice can differ from the country described in the source.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.