9q33.3q34.11 microdeletion syndrome

What it is

From: Orphanet

A partial monosomy of the long arm of chromosome 9 characterized by intellectual disability, developmental delay with pronounced speech delay, short stature, and muscular hypotonia. Common craniofacial dysmorphic features consist of microcephaly, prominent forehead, round face, arched eyebrows, upslanting palpebral fissures, strabismus, short nose, and thin upper lip. Other clinical findings include epilepsy, ataxia, unspecific brain MRI findings, early-onset primary dystonia, nail dysplasia, and bone malformations, in particular patellar abnormalities, epistaxis, and cutaneous-mucous telangiectasias.

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.

Abnormal shape of the palpebral fissure · Very frequent (99-80%)

The presence of an abnormal shape of the palpebral fissure.

Axial hypotonia · Very frequent (99-80%)

Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.

Broad chin · Very frequent (99-80%)

Increased width of the midpoint of the mandible (mental protuberance) and overlying soft tissue.

Bulbous nose · Very frequent (99-80%)

Increased volume and globular shape of the anteroinferior aspect of the nose.

Delayed speech and language development · Very frequent (99-80%)

A degree of language development that is significantly below the norm for a child of a specified age.

Dysphagia · Very frequent (99-80%)

Difficulty in swallowing.

Full cheeks · Very frequent (99-80%)

Increased prominence or roundness of soft tissues between zygomata and mandible.

Intellectual disability, severe · Very frequent (99-80%)

Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34.

Motor delay · Very frequent (99-80%)

A type of Developmental delay characterized by a delay in acquiring motor skills.

Nail dysplasia · Very frequent (99-80%)

The presence of developmental dysplasia of the nail.

Patellar dislocation · Very frequent (99-80%)

The kneecap normally is located within the groove termed trochlea on the distal femur and can slide up and down in it. Patellar dislocation occurs if the patella fully dislocates out of the groove.

Round face · Very frequent (99-80%)

The facial appearance is more circular than usual as viewed from the front.

Seizure · Very frequent (99-80%)

A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.

Thin vermilion border · Very frequent (99-80%)

Height of the vermilion of the medial part of the lip more than 2 SD below the mean, or apparently reduced height of the vermilion of the lip in the frontal view. The vermilion is the red part of the lips (and confusingly, the vermilion itself is also often referred to as being equivalent the lips).

Other findings in the same source

From: Orphanet

Additional reported features include Large forehead (Very frequent (99-80%)); Asthma (Frequent (79-30%)); Astigmatism (Frequent (79-30%)); Atypical behavior (Frequent (79-30%)); Bilateral coxa valga (Frequent (79-30%)); Constipation (Frequent (79-30%)); Epistaxis (Frequent (79-30%)); Highly arched eyebrow (Frequent (79-30%)); Inability to walk (Frequent (79-30%)); Microcephaly (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Childhood; Infancy

Inheritance in the source

From: Orphanet

Not applicable

Frequency and the population described

From: Orphanet

Reported case(s): 4.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Which doctor should you see?

The suggested department for discussing 9q33.3q34.11 microdeletion 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

The material gathered for this draft does not provide a complete condition-specific treatment pathway for 9q33.3q34.11 microdeletion 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.