17q23.1q23.2 microdeletion syndrome

Alternate names

17q23.1-q23.2 microdeletion syndrome; Del(17)(q23.1q23.2); Monosomy 17q23.1-q23.2; Monosomy 17q23.1q23.2; Chromosome 17q23.1-q23.2 deletion syndrome

Definition

17q23.1q23.2 microdeletion syndrome is a condition caused by a small deletion of genetic material from chromosome 17. The deletion occurs at a location encompassing bands 23.1 to 23.2 on the long (q) arm of the chromosome. People with 17q23.1q23.2 microdeletion syndrome may have developmental delay, microcephaly, short stature, heart defects and limb abnormalities.

Cause

The syndrome is caused by an interstitial deletion (a deletion that does not involve the ends of a chromosome) encompassing bands 23.1 to 23.2 on the long (q) arm of chromosome 17. Two transcription factors, TBX2 and TBX4, which belong to a family of genes implicated in a variety of developmental pathways including those of heart and limbs, are found within this 2.2Mb region. This suggests that they may play a part in the symptoms seen in this condition.

Inheritance

Parental FISH testing in most of the reported cases confirmed a de novo origin, meaning that the deletion was new to the family.

Signs and symptoms

17q23.1q23.2 microdeletion syndrome is characterized by developmental delay, microcephaly, short stature, heart defects and hand, foot and limb abnormalities. All individuals reported to date have had mild to moderate developmental delay, in particular delays in speech. Most have had heart defects, including patent ductus arteriosus or atrial septal defects. Limb abnormalities include long, thin fingers and toes, and hypoplasia (underdevelopment) of the patellae (knee caps). Scoliosis may also be present. Many patients have also had mild and unspecific unusual facial features.

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

• Delayed speech and language development(Deficiency of speech development)
• Long fingers
• Long toe (Increased length of toes)
• Mild global developmental delay
• Moderate global developmental delay

30%-79% of people have these symptoms

• Frontal bossing
• Intrauterine growth retardation(Prenatal growth deficiency)
• Microcephaly(Abnormally small skull)
• Patent ductus arteriosus
• Pulmonary arterial hypertension(Increased blood pressure in blood vessels of lungs)
• Short stature(Decreased body height)

5%-29% of people have these symptoms

• Abnormality of epiphysis morpholog(Abnormal shape of end part of bone)
• Atrial septal defect(An opening in the wall separating the top two chambers of the heart)
• Behavioral abnormality(Behavioral changes)
• Bifid nose(Indentation or clefting of the nose)
• Bilateral single transverse palmar creases
• Blepharitis(Inflammation of eyelids)
• Bulbous nose
• Chronic otitis media(Chronic infections of the middle ear)
• Clinodactyly of the 5th finger(Permanent curving of the pinkie finger)
• Congenital contracture
• Coxa magna
• Depressed nasal bridge(Depressed bridge of nose)
• Dyspnea(Trouble breathing)
• Epicanthus(Eye folds)
• Failure to thrive(Faltering weight)
• Gastroesophageal reflux(Acid reflux)
• Hearing impairment(Deafness)
• Highly arched eyebrow(Arched eyebrows)
• Hyperreflexia(Increased reflexes)
• Hypertelorism(Wide-set eyes)
• Limitation of joint mobility(Decreased joint mobility)
• Long eyelashes(Increased length of eyelashes)
• Malar flattening(Zygomatic flattening)
• Muscular hypotonia(Low or weak muscle tone)
• Narrow mouth(Small mouth)
• Patellar hypoplasia(Small kneecap)
• Pes planus(Flat feet)
• Protruding ear(Prominent ear)
• Sacral dimple(Spinal dimple)
• Sandal gap(Gap between 1st and 2nd toes)
• Scoliosis
• Shallow acetabular fossae
• Shawl scrotum(Scrotum surrounds penis)
• Strabismus(Cross-eyed)
• Widely spaced teeth(Wide-spaced teeth)

Diagnosis

The deletion can be identified by comparative genomic hybridization (CGH) microarray and fluorescence in situ hybridization (FISH).

NIH genetic and rare disease info

• NIH info on 17q23.1q23.2 microdeletion syndrome

17q23.1q23.2 microdeletion syndrome is a rare disease.

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