16q24.3 microdeletion syndrome

Alternate names

Del(16)(q24.3); Monosomy 16q24.3; Chromosome 16q24.3 microdeletion syndrome

Definition

16q24.3 microdeletion syndrome is a chromosome abnormality that can affect many parts of the body. People with this condition are missing a small piece (deletion) of chromosome 16 at a location designated q24.3.

Cause

This condition occurs due to missing of small piece (deletion) of chromosome 16 at a location designated q24.3.

Inheritance

• Chromosome testing of both parents can provide more information on whether or not the microdeletion was inherited.
• In most cases, parents do not have any chromosomal anomaly.
• However, sometimes one parent has a balanced translocation where a piece of a chromosome has broken off and attached to another one with no gain or loss of genetic material.
• The balanced translocation normally does not cause any signs or symptoms, but it increases the risk for having an affected child with a chromosomal anomaly like a microdeletion.

Signs and symptoms

Signs and symptoms may include developmental delay, characteristic facial features, seizures and autism spectrum disorder.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Autism
• High forehead
• Protruding ear(Prominent ear)

30%-79% of people have these symptoms

• Colpocephaly
• Frontal bossing
• High palate(Elevated palate)
• Hypoplasia of the corpus callosum(Underdevelopment of part of brain called corpus callosum)
• Intellectual disability, moderate(IQ between 34 and 49)
• Long philtrum
• Micrognathia(Little lower jaw)
• Optic nerve hypoplasia
• Periventricular heterotopia
• Pointed chin(Pointy chin)
• Seizure
• Smooth philtrum
• Ventriculomegaly
• Wide mouth(Broad mouth)

5%-29% of people have these symptoms

• Abnormal hair pattern(Abnormal distribution of hair)
• Anteverted nares(Nasal tip, upturned)
• Astigmatism(Abnormal curving of the cornea or lens of the eye)
• Biparietal narrowing
• Chronic otitis media(Chronic infections of the middle ear)
• Cryptorchidism(Undescended testes)
• Delayed speech and language development(Deficiency of speech development)
• Dilated cardiomyopathy(Stretched and thinned heart muscle)
• Dysphagia(Poor swallowing)
• Feeding difficulties(Feeding problems)
• Hearing impairment(Deafness)
• Highly arched eyebrow(Arched eyebrows)
• Hip dysplasia
• Increased mean corpuscular volume
• Kyphosis(Hunched back)
• Long face(Elongation of face)
• Mitral regurgitation
• Myopia(Close sighted)
• Nystagmus(Involuntary, rapid, rhythmic eye movements)
• Preauricular skin tag
• Proximal placement of thumb(Attachment of thumb close to wrist)
• Scoliosis
• Single median maxillary incisor(Only one upper front tooth)
• Strabismus(Cross-eyed)
• Thick vermilion border(Full lips)
• Thrombocytopenia(Low platelet count)
• Triangular face(Face with broad temples and narrow chin)
• Upslanted palpebral fissure(Upward slanting of the opening between the eyelids)
• Ventricular septal defect(Hole in heart wall separating two lower heart chambers)
• Visual impairment(Impaired vision)

Diagnosis

Chromosome disorders may be suspected in people who have developmental delays, intellectual disabilities and/or physical abnormalities.

Several types of genetic tests can identify chromosome disorders:

• Karyotyping
• Microarray (also called array CGH)
• Fluorescence in situ hybridization (FISH)

Treatment

Treatment is based on the signs and symptoms present in each person.

NIH genetic and rare disease info

• NIH info on 16q24.3 microdeletion syndrome

16q24.3 microdeletion syndrome is a rare disease.