Snijders Blok-Campeau syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Snijders Blok-Campeau syndrome is characterized by intellectual disability, speech problems, and distinctive facial features.

Intellectual disability in individuals with Snijders Blok-Campeau syndrome ranges from mild to severe. Some people with this condition also have low muscle tone (hypotonia), seizures, or autistic behaviors that affect communication and social interaction.

While some people with Snijders Blok-Campeau syndrome develop limited language, others acquire only a few words or never speak. If speech occurs, it usually develops after age 2. Affected individuals can experience stuttering, problems coordinating movements of the mouth and tongue (oromotor dysfunction), or difficulty producing the sequences of sounds and syllables needed to form words (apraxia). In general, people with this condition have a very social personality.

Individuals with Snijders Blok-Campeau syndrome have distinctive facial features. The eyes are frequently affected, and features often include widely spaced eyes (ocular hypertelorism), deep-set eyes, narrowed openings of the eyes (narrowed palpebral fissures), an increased distance between the inner corners of the eyes (telecanthus), and sparse eyebrows. Additional facial features can include full cheeks, a pointed chin, a prominent forehead (frontal bossing), a sunken appearance of the middle of the face (midface hypoplasia), a broad nasal bridge, low-set ears that may be rotated backward, and a thin upper lip. Affected individuals often have an abnormally sized head; most have an unusually large head (macrocephaly), though some have an unusually small head (microcephaly). Some people with Snijders Blok-Campeau syndrome have premature closure of certain bones of the skull (craniosynostosis), which can contribute to an abnormal head shape.

Most individuals with Snijders Blok-Campeau syndrome have vision problems, including farsightedness (hyperopia) or eyes that do not look in the same direction (strabismus).

About half of people with Snijders Blok-Campeau syndrome have brain abnormalities, such as enlarged spaces in the brain where cerebrospinal fluid (CSF) accumulates. Less commonly, affected individuals are born with a hole between the two upper chambers of the heart (atrial septal defect) or another problem with the heart's structure or function (congenital heart disease).

ORPHANET DEFINITION A rare, genetic, multiple congenital anomalies/dysmorphic syndrome characterized by moderate to severe intellectual disability, developmental delay, macrocephaly, speech delay, and hypotonia. Dysmorphic facial features include a high, broad, and/or prominent forehead, laterally sparse eyebrows, widely spaced and deeply-set eyes, narrow palpebral fissures, low-set ears, full/prominent cheeks, midface hypoplasia, thin upper lip, and a pointed chin. Additional variable manifestations include joint laxity, abnormality of vision (including hypermetropia, strabismus, and cerebral visual impairment), genital abnormalities in males, and inguinal, umbilical, or hiatal hernia.

Inheritance

From: MedlinePlus Genetics, National Library of Medicine

Autosomal dominant

Frequency in the source

From: MedlinePlus Genetics, National Library of Medicine

Reported case(s): 60.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Understanding terms used in the source

These definitions explain medical words used above. A definition is not evidence that another condition is present, and it does not predict how a symptom will develop. Ask the clinician which terms apply to the actual examination or test result.

Severe intellectual disability

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.

Cerebral visual impairment

A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.

Intellectual disability

The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.

Atrial septal defect

Atrial septal defect (ASD) is a congenital abnormality of the interatrial septum that enables blood flow between the left and right atria via the interatrial septum.

Prominent forehead

Forward prominence of the entire forehead, due to protrusion of the frontal bone.

When it may begin

From: MedlinePlus Genetics, National Library of Medicine

Infancy; Neonatal

Inheritance in the source

From: MedlinePlus Genetics, National Library of Medicine

Autosomal dominant

Frequency and the population described

From: MedlinePlus Genetics, National Library of Medicine

Reported case(s): 60.0; 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 dominant pattern means that one altered copy of a relevant gene can be sufficient for the condition. Some affected people inherit the change; others have a new change without an affected parent. The precise finding, family history and condition determine what this means for relatives.

Which doctor should you see?

The suggested department for discussing Snijders Blok-Campeau 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 Snijders Blok-Campeau 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.