Congenital Disorders Flashcards
(28 cards)
What is the definition of congenital malformations?
Abnormality present at birth that may not be detected until some time after birth.
List three common causes of congenital malformations.
- Chromosomal abnormalities
- Intrauterine injury to embryo or fetus
- Environmental factors
What is nondisjunction in the context of chromosomal abnormalities?
Failure of homologous chromosomes in germ cells to separate.
What are the outcomes of nondisjunction?
- Monosomy
- Trisomy
- Deletions
- Translocations
What is Turner’s Syndrome and its genotype?
Missing X chromosome in females; Genotype: 45, X.
What are the characteristic features of Turner’s Syndrome?
- Short stature
- Broad neck
- Widely spaced nipples
What is Triple X Syndrome and its genotype?
Extra X chromosome in females; Genotype: 47, XXX.
What is Klinefelter’s Syndrome and its genotype?
Extra X chromosome in males; Genotype: 47, XXY.
What are the characteristic features of Klinefelter’s Syndrome?
- Somewhat feminine body features
- Breast hypertrophy
- Atrophic testicles
- Subnormal intelligence
What is XYY Syndrome and its genotype?
Extra Y chromosome in males; Genotype: 47, XYY.
What are the characteristic features of XYY Syndrome?
- Some reduction in intelligence
- Taller than normal, but no specific body features
What is Fragile X Syndrome?
Abnormality of X chromosome near its tip, major cause of mental deficiency.
What genetic mutation is associated with Fragile X Syndrome?
Abnormally high number of CGG sequences in DNA.
What is the most common chromosomal abnormality?
Down Syndrome, caused by trisomy of chromosome 21.
What are the clinical manifestations of Down Syndrome?
- Developmental disabilities
- Cardiac malformation
- Major defects in other organ systems
What percentage of Down syndrome cases result from nondisjunction during gametogenesis?
95% of Down syndrome cases.
What is Translocation Down Syndrome?
Occurs when chromosome 21 is fused with chromosome 14 or another chromosome.
What is Mosaic Down Syndrome?
Some cells exhibit trisomy 21, other cells have a normal chromosome makeup.
What are the symptoms of Patau syndrome (trisomy of chromosome 13)?
- Cleft lip and palate
- Abnormal development of skull and brain
- Abnormal eye development
- Congenital heart defects
- Polydactyly
What is the outcome for most cases of Edward’s syndrome (trisomy of chromosome 18)?
Both usually fatal in neonatal period or early infancy.
What are some examples of harmful factors that can cause intrauterine injury?
- Harmful drugs
- Chemicals
- Radiation
- Maternal infections
What is multifactorial inheritance?
Combined effect of multiple genes interacting with environmental agents.
Give an example of a multifactorial defect.
Cleft lip, cleft palate, cardiac malformations, clubfoot, spina bifida, etc.
What is the purpose of ultrasound examination in prenatal diagnosis?
Detection of major structural abnormalities.
