RIDDLE syndrome

What it is

From: Orphanet

A rare, genetic, primary immunodeficiency disorder characterized by increased radiosensitivity(R), mild immunodeficiency (ID), dysmorphic features (D), and learning difficulties (LE).

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.

Chromosomal breakage induced by ionizing radiation · Very frequent (99-80%)

Increased amount of chromosomal breaks in cultured blood lymphocytes or other cells induced by treatment with ionizing radiation.

Decreased circulating IgA level · Very frequent (99-80%)

Decreased levels of immunoglobulin A (IgA).

Decreased circulating IgG level · Very frequent (99-80%)

An abnormally decreased level of immunoglobulin G (IgG) in blood.

Elevated alpha-fetoprotein · Very frequent (99-80%)

The concentration of alpha-fetoprotein in the blood circulation is above the upper limit of normal.

Immunodeficiency · Very frequent (99-80%)

Failure of the immune system to protect the body adequately from infection, due to the absence or insufficiency of some component process or substance.

Short stature · Very frequent (99-80%)

A height below that which is expected according to age and gender norms. Although there is no universally accepted definition of short stature, many refer to "short stature" as height more than 2 standard deviations below the mean for age and gender (or below the 3rd percentile for age and gender dependent norms).

Abnormal facial shape · Frequent (79-30%)

An abnormal morphology (form) of the face or its components.

Bronchitis · Frequent (79-30%)

Inflammation of the large airways in the lung including any part of the bronchi from the primary bronchi to the tertiary bronchi.

Chronic sinusitis · Frequent (79-30%)

A chronic form of sinusitis.

Pneumonia · Frequent (79-30%)

Inflammation of any part of the lung parenchyma.

Recurrent fever · Frequent (79-30%)

Periodic (episodic or recurrent) bouts of fever.

Recurrent pneumonia · Frequent (79-30%)

An increased susceptibility to pneumonia as manifested by a history of recurrent episodes of pneumonia.

Recurrent sinusitis · Frequent (79-30%)

A recurrent form of sinusitis.

Specific learning disability · Frequent (79-30%)

Impairment of certain skills such as reading or writing, coordination, self-control, or attention that interfere with the ability to learn. The impairment is not related to a global deficiency of intelligence.

Other findings in the same source

From: Orphanet

Additional reported features include Abdominal pain (Occasional (29-5%)); Abnormal cerebral white matter morphology (Occasional (29-5%)); Abnormal pulmonary interstitial morphology (Occasional (29-5%)); Arthritis (Occasional (29-5%)); Ataxia (Occasional (29-5%)); Clumsiness (Occasional (29-5%)); Conjunctival telangiectasia (Occasional (29-5%)); Decreased circulating total IgM (Occasional (29-5%)); Demyelinating peripheral neuropathy (Occasional (29-5%)); Diarrhea (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Adolescent; Infancy

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Reported case(s): 2.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing RIDDLE syndrome is Allergy and Immunology, with a allergist / clinical immunologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

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 history suggest an allergy, an immune problem or another explanation?
• How would any proposed allergy or immune test change care?
• Is an individual emergency plan needed, and who should understand it?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for RIDDLE syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

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.