Additional copy on human chromosome 21(Trisomy of Hsa21), occur due to error in cells division and appears with various physical and mental developmental disabilities including-: Alzheimer disease (A.D), Heart defects, Leukemia, Mental retardation this complex disorder known as Down syndrome (DS) (1). DS firstly discovered in England by John Langdon Down early as the 15^th century, a British doctor who firstly studied and named (Down syndrome) this mental and physical disorder (2). The various genes encoded in Hsa21 (Smallest human chromosome) are highly expressed due to the presence of additional copy (1). The developing infants with trisomy have high prospects of miscarriage and also an elevated risk of several therapeutic conditions (3). It is suggested that the frequencies of trisomic causes altered by maternal age and vary among 1 in 319 or 1000 live births (4–8). Chromosomal abnormality (DS) is the most frequent hereditary account of mental retardation and developing in generally 1 in 800 births (9). The various crucial genes yet identified on Hsa21, they elevated the current count of maximum to 400 (10). There are five micro RNAs have been determined in chromosome 21 (11, 12), they balanced the expression of alternative genes (13), and their role in DS is not completely known. In commercially growing countries, for normal life span of people with trisomy 21 is now more than 55 years of age (14). For diagnostic point of view a recent paper suggested that screening test like -: pregnancy associated plasma protein-A2 (PAPP-A2) as a novel second trimester biomarker for Trisomy 21(15).  Generally 0.45% human interpretations for Down syndrome are trisomy of chromosome 21 (16). Most of the children’s who suffered with Down syndrome has a strict scope of fall within the intellectual disability (17). During speaking, there are three types of complications observed in children -: 1) initial speaking and phonological defects, 2) fluency abnormalities like-: pause and cluttering and 3) constructive aphasia-type complications (18). Additional genetic material on Hsa21 leads to abnormal genes expression and furthermore these abnormalities results in excess key proteins expression, effect may varies according to  proteins are involved (19).