Investigator will also perform renal and low urinary tract Doppler ultrasound with measurement of renal dimension in order to determine if the kidneys of patients with high level of serum of endostatin are smaller than those of patients with normal level of endostatin. Data observed in Down syndrome children will be compared to control group 2age constituted by sex and age matched healthy children Urine microalbuminuria and urine microalbuminuria/creatinuria from the first urine in the morning will be evaluated.