Brachydactyly (Greek βραχύς = "short" plus δάκτυλος = "finger"), is a medical term which literally means "short finger". The shortness is relative to the length of other long bones and other parts of the body. Brachydactyly is an inherited, usually dominant trait. It most often occurs as an isolated dysmelia, but can also occur with other anomalies as part of many congenital syndromes. Brachydactyly can also be a signal that one will be at risk for heart problems as they age.Nomograms for normal values of finger length as a ratio to other body measurements have been published. In clinical genetics, the most commonly used index of digit length is the dimensionless ratio of the length of the third (middle) finger to the hand length. Both are expressed in the same units (centimeters, for example) and are measured in an open hand from the fingertip to the principal creases where the finger joins the palm and where the palm joins the wrist. Types
There are several types of Brachydactyly:

Other syndromes
In the above brachydactyly syndromes, short digits are the most prominent of the anomalies, but in many other syndromes (Down syndrome, Rubinstein–Taybi syndrome, etc. ), brachydactyly is a minor feature compared to the other anomalies or problems comprising the syndrome.
Compression of the brachial plexus may be identified by weakness of the muscles in the hand, near the base of the thumb. Compression of the subclavian artery is often diagnosed by finding a positive Adsons sign on examination, where the radial pulse in the arm is lost during abduction and external rotation of the shoulder. A positive Adsons sign is non-specific for the presence of a cervical rib however, as many individuals without a cervical rib will have a positive test. Compression of the sympathetic chain may cause Horners syndrome. Other animals
Many vertebrates, especially reptiles, have cervical ribs as a normal part of their anatomy rather than a pathological condition. Some sauropods had exceptionally long cervical ribs; those of Mamenchisaurus hochuanensis were nearly 4 meters long. In birds, the cervical ribs are small and completely fused to the vertebrae. In mammals, the ventral parts of the transverse processes of the cervical vertebrae are the fused-on cervical ribs. Recent studies have also found a high percent of cervical ribs in woolly mammoths. It is believed that the decline in mammoth numbers may have forced inbreeding within the species which in turn had increased the number of mammoths being born with cervical ribs. Cervical ribs have been connected with leukaemia in human children, so it has given scientists new evidence to believe that the mammoths extinction was attributed to the condition. References


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