- Holt-Oram syndrome
Infobox_Disease
Name = PAGENAME
Caption =
DiseasesDB = 5988
ICD10 = ICD10|Q|87|2|q|80
ICD9 =
ICDO =
OMIM = 142900
MedlinePlus =
eMedicineSubj = med
eMedicineTopic = 2940
eMedicine_mult = eMedicine2|ped|1021 | MeshID =Holt-Oram syndrome is a disorder that affects bones in the
arm s andhand s (the upper limbs) and may also causeheart problems.Presentation
All people with this disorder have at least one limb abnormality that affects bones in the wrist (carpal bones). Often, these wrist bone abnormalities can be detected only by
X-ray . Affected individuals may have additional bone abnormalities that can include a missing thumb or a thumb that looks like a finger, partial or complete absence of bones in the forearm, an underdeveloped bone of the upper arm, and abnormalities that affect the collar bone and shoulder blades. Bone abnormalities may affect each arm differently, and the left side can be affected more than the right side. In some cases, only one arm and/or hand is affected.About 75 percent of individuals with Holt-Oram syndrome have heart problems. The most common problem is a defect in the muscular wall, or septum, that separates the right and left sides of the heart.
Atrial septal defect s (ASD) are caused by a hole in the septum between the left and right upper chambers of the heart (atria), andventricular septal defect s (VSD) are caused by a hole in the septum between the left and right lower chambers of the heart (ventricles). Sometimes people with Holt-Oram syndrome havecardiac conduction disease , which is caused by abnormalities in the electrical system that coordinates contractions of the heart chambers. Cardiac conduction disease can lead to problems such as a slow heart rate (bradycardia ) or a rapid and ineffective contraction of the heart muscles (fibrillation ). Cardiac conduction disease can occur along with other heart defects (such as septal defects) or as the only heart problem in people with Holt-Oram syndrome.Genetics
Mutations in the "
TBX5 " gene cause Holt-Oram syndrome.cite journal |author=Li QY, Newbury-Ecob RA, Terrett JA, "et al" |title=Holt-Oram syndrome is caused by mutations in TBX5, a member of the Brachyury (T) gene family |journal=Nat. Genet. |volume=15 |issue=1 |pages=21–9 |year=1997 |month=January |pmid=8988164 |doi=10.1038/ng0197-21 |url=http://dx.doi.org/10.1038/ng0197-21] cite journal |author=Basson CT, Bachinsky DR, Lin RC, "et al" |title=Mutations in human TBX5 [corrected] cause limb and cardiac malformation in Holt-Oram syndrome |journal=Nat. Genet. |volume=15 |issue=1 |pages=30–5 |year=1997 |month=January |pmid=8988165 |doi=10.1038/ng0197-30 |url=http://dx.doi.org/10.1038/ng0197-30] The "TBX5" gene plays a role in the development of the heart and upper limbs before birth. In particular, this gene appears to be important for the process that divides the developing heart into four chambers (cardiac septation). The "TBX5" gene also appears to play a critical role in regulating the development of bones in the arm and hand. Mutations in this gene probably disrupt the development of the heart and upper limbs, leading to the characteristic features of Holt-Oram syndrome.Holt-Oram syndrome is considered an
autosomal dominant disorder. This means the defective gene is located on anautosome , and only one copy of the gene, inherited from a parent who has the disorder, is sufficient to cause the disorder.Other cases of Holt-Oram syndrome are sporadic, and result from new mutations in the TBX5 gene that occur in people with no history of the disorder in their family. Holt-Oram syndrome is estimated to affect 1 in 100,000 individuals.
Eponym
It is named for
Mary Holt andSamuel Oram . [WhoNamedIt|synd|4110] cite journal |author=HOLT M, ORAM S |title=Familial heart disease with skeletal malformations |journal=Br Heart J |volume=22 |issue= |pages=236–42 |year=1960 |month=April |pmid=14402857 |pmc=1017650 |doi= |url=http://heart.bmj.com/cgi/pmidlookup?view=long&pmid=14402857]ee also
*
Absent radius References
External links
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* [http://health.enotes.com/genetic-disorders-encyclopedia/holt-oram-syndrome Holt-Oram syndrome: Encyclopedia of Genetic Disorders]
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