Share on: Facebook Twitter. Show references What is Down syndrome? National Down Syndrome Society. Accessed Dec. Down syndrome fact sheet. Messerlian GM, et al. Down syndrome: Overview of prenatal screening. National Library of Medicine. Down syndrome. Genetics Home Reference. Facts about Down syndrome. Centers for Disease Control and Prevention. Frequently asked questions. Prenatal genetic diagnostic tests. American College of Obstetricians and Gynecologists. Ostermaier KK. Down syndrome: Management.
Down syndrome: Clinical features and diagnosis. Accessed Jan. Gabbe SG, et al. Genetic screening and prenatal genetic diagnosis. In: Obstetrics: Normal and Problem Pregnancies. Philadelphia, Pa. Rink BD, et al. Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome Even though people with Down syndrome might act and look similar, each person has different abilities.
People with Down syndrome usually have an IQ a measure of intelligence in the mildly-to-moderately low range and are slower to speak than other children. Down syndrome remains the most common chromosomal condition diagnosed in the United States. Each year, about 6, babies born in the United States have Down syndrome.
This means that Down syndrome occurs in about 1 in every babies. There are three types of Down syndrome. There are two basic types of tests available to detect Down syndrome during pregnancy: screening tests and diagnostic tests.
A screening test can tell a woman and her healthcare provider whether her pregnancy has a lower or higher chance of having Down syndrome. Screening tests do not provide an absolute diagnosis, but they are safer for the mother and the developing baby. Diagnostic tests can typically detect whether or not a baby will have Down syndrome, but they can be more risky for the mother and developing baby.
Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby; no one can predict this. This can be overcome by using of multiple target amplifications and enrichment of cell-free fetal DNA which are still under research trail. Next recent method added to the list is next generation sequencing NGS which is based on the principle of clonally amplified DNA templates or, most recently, single DNA molecules are sequenced in a massively parallel fashion within a flow cell [ 72 , 73 ].
Fan et al. Both groups extracted cell-free DNA from maternal plasma samples from both euploid and trisomy pregnancies. DNA from each sample was sequenced on the Illumina Genome Analyzer, and each sequence read was aligned to the reference human genome. Chiu et al. Cell-free DNA was extracted from 15 pregnant women, 5 of whom carried trisomy 21 fetuses and it was clonally amplified by emulsion PCR, and sequenced in 1 chamber of an 8-chamber SOLiD slide.
As reported earlier with the Illumina Genome Analyzer, a nonuniform distribution of aligned sequence reads was observed with the SOLiD data. Going forward, one can expect streamlining and automation of technical processes and data analysis, coupled with reduced sequencing costs. Forty years after the discovery of circulating fetal cells, the vision of NIPD appears clearer and closer. One of the hallmarks of DS is the variability in the way that the condition affects people with DS.
With the third 21st chromosome existing in every cell, it is not surprising to find that every system in the body is affected in some way. However, not every child with DS has the same problems or associated conditions. Parents of children with DS should be aware of these possible conditions so they can be diagnosed and treated quickly and appropriately.
The goal of the study is to point out the most common problems of which parents should be aware. Timely surgical treatment of cardiac defects during first 6 months of life may prevent from serious complications. A balance diet and regular exercise are needed to maintain appropriate weight.
Feeding problems and failure to thrive usually improve after cardiac surgery. A DS child should have regular check up from various consultants. These include:. Child psychiatrist - A child psychiatrist should lead liaison interventions, family therapies, and psychometric evaluations. DS or Trisomy 21, being the most common chromosomal abnormality among live born infants, is associated with a number of congenital malformations.
Several theories have been put forward to increase our understanding in phenotype and genotype correlation. This reviews also provides the detailed description on the application of techniques to prenatal diagnosis in DS. Since various clinical conditions are associated with DS, hence the management of these patients requires an organized multidisciplinary approach and continuous monitoring of these patients which has been discussed in this review article.
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Trends Pharmacol Sci. Natural gene-expression variation in Down syndrome modulates the outcome of gene-dosage imbalance. Am J Hum Genet. Fetal loss in Down syndrome pregnancies.
Prenat Diagn. Genotype—phenotype correlations in Down syndrome identified by array CGH in 30 cases of partial trisomy and partial monosomy chromosome Eur J Hum Genet.
FEBS J. Chromosome 21 and Down syndrome: from genomics to pathophysiology. Nat Rev Genet. Mapping of Down syndrome phenotype on chromosome 21 at the molecular level. Biomed Pharmacother. New York: McGraw-Hill; Pritchard MA, Kola I. The "gene dosage effect" hypothesis versus the "amplified developmental instability" hypothesis in Down syndrome.
J Neural Transm Suppl. Patterson D. Genetic mechanisms involved in the phenotype of Down syndrome. Shapiro BL.
Down syndrome—a disruption of homeostasis. Am J Med Genet. Molecular mapping of twenty-four features of Down syndrome on chromosome The genetic architecture of Down syndrome phenotypes revealed by high-resolution analysis of human segmental trisomies. Niebuhr E. Down's syndrome. The possibility of a pathogenetic segment on chromosome no. J Intellect Disabil Res. Br J Psychiatry. Prevalence of dementia and impact on intellectual disability services.
Ment Retard. The prevalence of dementia in Down syndrome. Lai F, Williams RS. A prospective study of Alzheimer disease in Down syndrome.
Arch Neurol. Int J Alzheimers Dis. J Neurol Sci. Neurobiol Aging. Urbano R. Health issues among person with down syndrome. CRELD1 mutations contribute to the occurrence of cardiac atrioventricular septal defects in Down syndrome. Craig B. Atrioventricular septal defect: from fetus to adult. Identification of a complex congenital heart defect susceptibility locus by using DNA pooling and shared segment analysis.
Hum Mol Genet. Detailed mapping of a congenital heart disease gene in chromosome 3p Acute lymphatic leukemia: Report of a case in eleventh month mongolina idiot. New Orleans Med Surg J. Krivit W, Good RA. Simultaneous occurrence of mongolism and leukemia; report of a nationwide survey. Nat Genet.
A lineage-selective knockout establishes the critical role of transcription factor GATA-1 in megakaryocyte growth and platelet development.
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