Genetically Transmitted Disorder: How to Detect Down's Syndrome

Introduction

Down’s Syndrome, also known as Trisomy 21, is the most common genetically transmitted disorder(1), and is characterized by the presence of part of or a whole third 21st¬¬ chromosome(2). Parents of affected individuals usually do not exhibit Down’s Syndrome(3). Because it is caused by a double 21st chromosome in either of the parental gametes(4), Down’s syndrome is a chronic disease.

Down’s Syndrome’s effects vary widely from patient to patient, but in most cases they are a form of mental impairment(5), in fact the average mental abilities of an affected adult are comparable to those of a child(3)¬. Another common trait is a weak immune system(3).

Physical Symptoms

The following table(3)(6) provides the percentages of occurrence of some of the other most common physical symptoms.

Trait/symptom Per. (%) Trait/symptom Per. (%)

Narrow palate 76 Slanted eyes 60

Flat head 74 Bent last finger distal phalanx 57

Flat nose 68 White spots in iris 56

Toes separation 68 Heart defects 40

Neurological Symptoms

The most common neurological symptom is a reduced Intellective Quotient (IQ). Most recipients of Down’s syndrome exhibit mild IQ (approx. 60), but greater mental impairments are also diffused(11). Therefore affected people will possess less intellectual proficiency compared to peers. The majority of Down’s cases show better understanding than speech. Social relations are instead normal. Only in 5% of cases autism is related to Down’s syndrome, but a form of mental illness has a higher chance to occur, namely 30%. Also, Alzheimer’s disease affects 10% of people who reach the age of 40(11).

Sensorial Symptoms

Disorders related to sight are likely to arise in half of the affected population. Strabismus and cataracts touch 20%...

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...y in men with Down syndrome: a case report".Fertil Steril 86 (6): 1765.e1–3.

(14) Jeffrey S. Dungan &; Sherman Elias (Last revision 2008). "Prenatal diagnostic testing". Merck manual home health handbook.

(15) Alfirevic Z, Sundberg K, Brigham S (2003). "Amniocentesis and chorionic villus sampling for prenatal diagnosis". In Alfirevic, Zarko. Cochrane Database Syst Rev (3)

(16) "Down Syndrome and Other Abnormalities of Chromosome Number". Nelson textbook of pediatrics.(19th ed. ed.). Philadelphia: Saunders. 2011. Chapter 76.2.

(17) Chervenak, FA; McCullough, LB (Apr 2010). "Ethical considerations in first-trimester Down syndrome risk assessment.". Current opinion in obstetrics & gynecology 22 (2): 135–8.

(18) Bill J Leonard, Jill Y. Crainshaw (2013).Encyclopedia of religious controversies in the United States. (2nd ed. ed.). Santa Barbara, Calif.: ABC-CLIO. p. 278.