ABNORMAL FINGER LENGTH IS A VERY COMMON FEATURE IN THE MOST COMMON SYNDROMES!
Early in the 20th century scientists discovered that abnormal finger length is a typical minor physical anomaly (MPA) in the most common genetic disorders. However, in order to understand the implications of finger length variations it is important to become aware that even in these syndromes one can observe considerable overlap with normal finger length variations. An overview is presented here for finger length in various syndromes.
Many syndromes are featured with abnormal finger length. The picture below presents an overview of typical finger length variations in some of the most common syndromes, in respective: Down syndrome (trisomy 21), Fragile-X syndrome, and Marfan syndrome.
Typical finger length variations in Down syndrome, Fragile-X syndrome & Marfan syndrome:
NOTICE: Despite the strong link between abnormal finger length and genetic disorders, abnormal finger length in isolation should not be associated directly with these disorders. Multiple minor physical anomalies (MPA's) are always required to make a direct connection between finger length and any disorder.
usually short fingers!
Finger length in Down syndrome is usually featured with abnormally short fingers [brachydactyly], which is re-defined here as a 'finger length index' below 0.80 (see blue color in the picture at the top of this article). Down syndrome fingers are usually relatively short (below average) in the perspective of palm width and palm length.
Though Down syndrome is seen in only about 1 in 1000 births, it might be interesting to read more about the many typical hand features - see: hand signs in Down syndrome.
often short fingers!
Finger length in Fragile-X syndrome is usually featured with below average short fingers, but usually not abnormally short (see yellow color in the picture above). Fragile-x syndrome fingers are usually only relatively short (below average) in the perspective of palm width; finger length in the perspective of palm length is only in a minority of cases clearly above average.
Though Down syndrome is seen in only about 1 in 4000 births, up to 1 in 250 females and 1 in 800 males are carriers of Fragile X premutation. It might be interesting to read more about the many typical hand features in Fragile-X syndrome - see: hand signs in Fragile-X syndrome.
usually long fingers!
Finger length in Marfan syndrome is often featured with abnormally long fingers [dolichodactyly] (more well-known is the reference to so-called long, slender 'spider fingers', a.k.a. arachnodactyly), which is re-defined here as a 'finger length index' above 0.96 (see also the green color in the picture at the top of this article). Marfan syndrome fingers are often relatively long (below average) especially in the perspective of palm width; in the perspective of palm length the fingers are often of above average length, but inside the normal range.
Though Marfan syndrome is seen in only about 1 in 5000 births, estimates are that about 50% of Marfan adults remain undiagnosed. Therefore the Marfan syndrome hand test might assist to help identify these people.
JUNE 8, 2014 UPDATE:
'When extraordinary long finger length becomes a minor physical anomaly'!