EX.M8

PEDIATRIC CONGENITAL ABNORMALITIES What are the four types of structural defects that can result in a chain of defects (sequence) by the time of birth? 1. Malformation. Poor formation of tissue. 2. Deformation. Unusual forces acting on normal tissue/structure. (commonly environmental forces). 3. Disruption. Breakdown of normal tissue by external factors. 4. Dysplasia. Abnormal Organization of cells in tissue. What's a common example of Congenital Disruption? Associated defects? Mechanism of potential Sequence? Amniotic Band Disruption. 1. Associated defects: oligodactyly (deficiency in number of digits) or extremity amputation. 2. Disruption sequence due to secondary disruption of blood supply to developing tissues. Defects can vary depending on where the amniotic band/blood supply disruption occurs. What's a common example of Congenital Dysplasia? Associated defects? Potential Sequence? Skeletal Dysplasia. Achondroplasia is the most common. 1. Associated defects: shortened limbs compared to head and trunk; microencephaly. 2. Potential Dysplasia Sequence: - bowing of the legs. - dental malocclusion. - obstructive apnea. - hearing loss. What is the most common Congenital Abnormality of chromosomal number? Down Syndrome; Trisomy 21. What is the average incidence of Down Syndrome? - In mothers aged 15-29? - 30-34? - 35-39? - 40-44? - Over 45? 1 in every 1,000 births. - 1 in 1,500. - 1 in 800. - 1 in 270. - 1 in 100. - 1/50. What are the three Chromosomal Alterations seen in Down Syndrome? What are their occurrences? 1. Nondisjunction, 94%. Event most commonly occurs in maternal meiosis phase I, resulting in three copies of chromosome 21 (full trisomy). 2. Robertsonian Translocation, 3.3%. Most commonly involves fusion of the long arms (q) of chromosomes 14 and 21. - Typically younger mothers. Some evidence of increased paternal age being a factor. 3. Mosaicism, 2.4%. One population with normal chromosome complement, and one population with trisomy 21. Show varying severity of phenotype depending on penetrance. Usually less severe - Typically higher I.Q. and more complete growth. Harder to initially diagnosis. When is Down Syndrome most commonly Diagnosed? What are the primary diagnostic features? 1. The newborn period. 2. Primary features are: - Hypotonia. - Poor Moro reflex. - Characteristic facial appearance: brachycephaly, flattened occiput, hypoplastic midface, flattened nasal bridge, and large protruding tongue. - Loose folds in posterior neck. - Short, broad hands with single transverse palmar crease (Simian Crease). - Infants tend to have normal birthweight/length. What are the most common visual and hearing abnormalities seen in Down Syndrome? 1. Myopia (nearsightedness) seen in 70% of cases, and speckling of the iris (Brushfield Spots). 2. Conductive hearing loss seen in 66% of cases. How common is congenital heart disease in children with Down Syndrome? What is the most common cardiac defect? 1. Congenital heart disease is seen in approximately 50% of cases, including atrioventricular canal, ventriculoseptal or anteroseptal defects, and valvular disease. Major cause for early mortality. 2. Endocardial cushion defect (AV canal, septal defects) is most common (40% of those with CHD). What are the general characteristics of growth/maturity in a healthy individual with Down Syndrome? 1. Good babies, happy/friendly children. 2. Growth is slow during first 8 years: - Improvement of muscle tone. - Poor coordination. - Short stature. 3. Mental progress slows with age: - I.Q. of 25-50. - Tend toward mimicry. 4. Underdevelopment of sexual organs: - Small penis, decreased testicular volume. - Rare fertility in females, none reported in males. What is the average life expectancy of an individual with Down Syndrome? Most common cause of death? 1. Most live well into their 20s and 30s if they survive the first year. -Survival to 1 year: 76.3% - To 5 years: 61.8% - To 10 years: 57.1% - To 20 years: 53.1% - To 30 Years: 49.9% 2. Most common cause of death before 1 year is CHD (endocardial cushion defect = AV canal). After 1 year, most common cause becomes respiratory disease (pneumonia). What is the recurrence risk for parents who have a child with Down Syndrome? Empiric recurrence risk is 1% (trisomy 21).