Ratios of body measurements can aid in recognition of Marfan's syndrome.
Parameters:
(1) upper body segment length in cm (from top of skull to the top of the symphysis pubis)
(2) lower body segment length in cm (from the top of symphysis pubis to floor)
(3) arm span in cm (both arms outstreched at 90 degrees to body)
(4) race
(5) age
Other authors use the midportion of the symphysis pubis to define segments.
(upper body segment) + (lower body segment) = height
ratio of upper to lower body segment =
= (upper segment length) / (lower segment length)
arm span to height ratio =
= (arm span in cm) / (height in cm)
Interpretation:
• In Marfan syndrome the arm span to height ratio is > 1.05.
• In an adolescent or adult white patient with Marfan syndrome the upper to lower body segment ratio is < 0.85.
• In an adolescent or adult black patient with Marfan syndrome the upper to lower body segment ratio is < 0.78.
• Asian and Afro-Caribbean patients may have different cutoffs.
|
Age in Years
|
Body Segment Ratio in Marfan Syndrome
|
|
<= 5 years
|
< 1.0
|
|
6 or 7 years
|
< 0.95
|
|
8 or 9 years
|
< 0.9
|
|
>= 10 years
|
see above
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