Determination of the sensitivity and secificity of hypertrophy of hyponychium as a new diagnodtic sing in down syndrome

down syndrome is the most common known chromosomal disorder in man.this syndrome has many sings and symptoms which are variable in frequency.taking all the signs and symproms in to consideration,diagnosis of down syndrome is not a difficult task-however in the past it was difficult to diagnose this syndrome based on a single clinical sign,until  hypertrophy of hyponichium was first introduced by daie(1988) as a new sign,that is seen in all of down syndrome patients.to determine precisely the sensitivity and specificity of this sign and its frequenxy in different fingers and toes,this research was conducted on 67 infants and children with down syndrome and 82 normal controls. sensitivity of hypertrophy of  hyponychium in diagnose of down  syndrome was found to be 100% with the confidence interval of 95%(93.24-100) and the secificity of 98.78%(92.45-99.94) the frequency of this clinical sign was highest in the hands particularly the third and fourth fingers.thus,it is now possible to clinically ndiagnose this syndrome with high level of confidence following careful examination of fingers in newborns.