IMAGe syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

The combination of intrauterine growth restriction, metaphyseal dysplasia, adrenal hypoplasia congenita, and genital anomalies is commonly known by the acronym IMAGe. This rare syndrome has signs and symptoms that affect many parts of the body.

Most affected individuals grow slowly before birth (intrauterine growth restriction) and are small in infancy. They have skeletal abnormalities that often become apparent in early childhood, although these abnormalities are usually mild and can be difficult to recognize on x-rays. The most common bone changes are metaphyseal dysplasia and epiphyseal dysplasia; these are malformations of the ends of long bones in the arms and legs. Some affected individuals also have an abnormal side-to-side curvature of the spine (scoliosis) or thinning of the bones (osteoporosis).

Adrenal hypoplasia congenita is the most severe feature of IMAGe syndrome. The adrenal glands are a pair of small glands on top of each kidney. They produce a variety of hormones that regulate many essential functions in the body. Underdevelopment (hypoplasia) of these glands prevents them from producing enough hormones, a condition known as adrenal insufficiency. The signs of adrenal insufficiency begin shortly after birth and include vomiting, difficulty with feeding, dehydration, extremely low blood glucose (hypoglycemia), and shock. If untreated, these complications can be life-threatening.

The genital abnormalities associated with IMAGe syndrome occur only in affected males. They include an unusually small penis (micropenis), undescended testes (cryptorchidism), and the opening of the urethra on the underside of the penis (hypospadias).

Several additional signs and symptoms have been reported in people with IMAGe syndrome. Some affected individuals have distinctive facial features, such as a prominent forehead, low-set ears, and a short nose with a flat nasal bridge. Less commonly, people with this condition have premature fusion of certain bones of the skull (craniosynostosis), a split in the soft flap of tissue that hangs from the back of the mouth (cleft or bifid uvula), a high-arched roof of the mouth (palate), and a small chin (micrognathia). Other possible features of IMAGe syndrome include high levels of calcium in the blood (hypercalcemia) or urine (hypercalcuria) and a shortage of growth hormone in childhood that results in short stature.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

IMAGe syndrome is caused by mutations in the CDKN1C gene. This gene provides instructions for making a protein that helps control growth before birth. The mutations that cause IMAGe syndrome alter the structure and function of the CDKN1C protein, which inhibits normal growth starting in the early stages of development before birth. Researchers are working to determine how these genetic changes underlie the bone abnormalities, adrenal gland underdevelopment, and other signs and symptoms of this condition.

People inherit one copy of most genes from their mother and one copy from their father. For most genes, both copies are fully turned on (active) in cells. The CDKN1C gene, however, is most active when it is inherited from a person's mother. The copy of CDKN1C inherited from a person's father is active at much lower levels in most tissues. This sort of parent-specific difference in gene activation is caused by a phenomenon called genomic imprinting. When genomic imprinting reduces the activity of the copy of a gene inherited from the father, that gene is said to be paternally imprinted.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

The inheritance of IMAGe syndrome is complex. The condition is described as having an autosomal dominant inheritance pattern because one copy of the altered CDKN1C gene in each cell is sufficient to cause the disorder. However, because this gene is paternally imprinted, IMAGe syndrome results only when the mutation is present on the maternally inherited copy of the gene. When a mutation affects the paternally inherited copy of the CDKN1C gene, it does not cause health problems. Therefore, IMAGe syndrome is passed only from mothers to their children.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

IMAGe syndrome is very rare, with only about 20 cases reported in the medical literature. The condition has been diagnosed more often in males than in females, probably because females do not have associated genital abnormalities.

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.

Abnormality of the genital system · Very frequent (99-80%)

An abnormality of the genital system.

Adrenal hypoplasia · Very frequent (99-80%)

Developmental hypoplasia of the adrenal glands.

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.

Depressed nasal bridge · Very frequent (99-80%)

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Frontal bossing · Very frequent (99-80%)

Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.

Hydronephrosis · Very frequent (99-80%)

Severe distention of the kidney with dilation of the renal pelvis and calices.

Hypogonadism · Very frequent (99-80%)

A decreased functionality of the gonad.

Hypospadias · Very frequent (99-80%)

Abnormal position of urethral meatus on the ventral penile shaft (underside) characterized by displacement of the urethral meatus from the tip of the glans penis to the ventral surface of the penis, scrotum, or perineum.

Other findings in the same source

From: Orphanet

Additional reported features include Hypotonia (Very frequent (99-80%)); Intrauterine growth retardation (Very frequent (99-80%)); Low-set ears (Very frequent (99-80%)); Metaphyseal dysplasia (Very frequent (99-80%)); Micromelia (Very frequent (99-80%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing IMAGe 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.

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.