12q14 microdeletion syndrome

Alternate names

Osteopoikilosis-short stature-intellectual disability syndrome; Del(12)(q14); Deletion 12q14; Monosomy 12q14

Definition

12q14 microdeletion syndrome is a genetic syndrome caused by a missing piece of chromosome 12. The chromosomal range of the deletions extends from 12q13.3q15.<ref>Lynch, S. A., Foulds, N., Thuresson, A. C., Collins, A. L., Annerén, G., Hedberg, B. O., Delaney, C. A., Iremonger, J., Murray, C. M., Crolla, J. A., Costigan, C., Lam, W., Fitzpatrick, D. R., Regan, R., Ennis, S., & Sharkey, F. (2011). The 12q14 microdeletion syndrome: six new cases confirming the role of HMGA2 in growth. European journal of human genetics : EJHG, 19(5), 534–539. https://doi.org/10.1038/ejhg.2010.215</ref>.

Epidemiology

This is a rare syndrome and the prevalence is thought to be less than 1 in 1,000,000 worldwide.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

• 12q14 microdeletion syndrome can be inherited in families in an autosomal dominant pattern. This means that a parent who has this deletion has a 50-50 or 1 in 2 chance of passing it on to each of his or her children.
• In some cases, this deletion occurs for the first time in a person (de novo), and is not inherited from a parent.

Signs and symptoms

• The signs and symptoms of 12q14 microdeletion syndrome can be different from person to person depending on the size of the missing piece of chromosome and the genes involved.
• In general, people with this syndrome have growth delay that starts before they are born, short stature, and poor weight gain.
• They may have feeding difficulties, speech and developmental delay, and mild intellectual disability.
• Some people with this syndrome have a triangular shaped face and a large forehead.
• Many have small areas of increased bone density that show up as bright spots on x-rays, a condition called osteopoikilosis.
• Osteopoikilosis does not cause pain or other symptoms.
• It has been suggested 12q14 microdeletions that include the HMGA2 gene cause some cases of Russell-Silver syndrome, because people with Russell-Silver syndrome and people with 12q14 microdeletion syndromes have similar signs and symptoms.

Diagnosis

12q14 microdeletion syndrome can be diagnosed through genetic testing, either a chromosomal microarray test or whole exome sequencing. Both tests can determine the size of the microdeletion and which genes are missing.

Treatment

• There is no specific treatment for 12q14 microdeletion syndrome.
• Growth problems may be treated with growth hormone therapy.
• If developmental delay or an intellectual disability is present, early educational intervention and early services can be helpful.

Prognosis

There is little published information about the long-term outlook for people with 12q14 microdeletion syndrome. In general, quality of life and possible medical complications likely depends on the type and severity of the signs and symptoms a person has. Several adults were found to have a 12q14 microdeletion who were healthy and without other symptoms of 12q14 microdeletion. Therefore more research needs to be done to understand how this microdeletion may affect a person.

References

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NIH genetic and rare disease info

• NIH info on 12q14 microdeletion syndrome

12q14 microdeletion syndrome is a rare disease.

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