Lesson 8 Genetic Disorders And Congenital Anomalies PDF

ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES OUTLINE for GENETIC A. AUTOSOMAL DOMINANT DISORDERS: DISORDERS 1. MUTATION manifested in the...

ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES OUTLINE for GENETIC A. AUTOSOMAL DOMINANT DISORDERS: DISORDERS 1. MUTATION manifested in the heterozygous state 2. MENDELIAN DISORDERS a. Autosomal dominant at least 1 parent of an b. Autosomal recessive index case is usually c. X-linked d/o affected d. Marfan Syndrome e. Ehlers Danlos Syndrome both males & females are (EDS) affected & both can transmit the condition 3. CHROMOSOMAL DISORDERS a. Trisomy 21 seen in : b. Trisomy 18 c. Trisomy 13 Neurofibromatosis 1 d. Klinefelter Syndrome (nervous) e. Turner Syndrome Familial Genetic disorders are far Hypercholesterolemia more common than is widely (metabolic) appreciated Huntington Disease Frequency: 670 per 1000 (nervous) 50% of spontaneous Polycystic Kidney Disease abortuses during the early (urinary) months of pregnancy have chromosomal abnormalities Osteogenesis Imperfecta (skeletal) MUTATION – permanent change in the B. AUTOSOMAL RECESSIVE DNA DISORDERS - may result in partial or complete deletion of a make up the largest gene category of mendelian - interferes w/ CHON disorders synthesis Features: MENDELIAN DISORDERS 1. the trait does not - disorder related to usually affect the parents mutations in single genes of the affected individual ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES but siblings may show the have the probability of disease receiving the mutant gene 2. siblings have 1 chance 2. the heterozygous female in 4 of having the trait expresses the disorder (25% for each birth) partially 3. if the mutant gene occurs w/ a low frequency seen in: in the population, there is a strong likelihood that Duchenne Muscular Dystrophy the affected individual is (musculoskeletal) a product of a consanguineous marriage Hemophilia A & B (hematologic) seen in : G6PD (hematologic) Cystic Fibrosis (metabolic) Diabetes insipidus (metabolic) Wilson’s dx (metabolic) Fragile – X Syndrome Sickle Cell Anemia (nervous) (hematologic) D. MARFAN’s SYNDROME Cong Adrenal hyperplasia (endocrine) disorder of connective tissues C. X-LINKED DISORDERS w/ changes in the skeleton all sex-linked disorders (tall & long extremities), (XX,XY) are X-linked & eyes (ectopia lentis) & almost all are recessive CardioVS (mitral valve prolapse) X-linked dominant conditions like the Vit D 1 in 5000 resistant rickets are NOT that common defect in FIBRILLIN-1 Features: E. EHLER’s DANLOS SYNDROME 1. an affected male does (EDS) not transmit the disorder to his sons but all defect in FIBRILLAR daughters are carriers; COLLAGEN sons of heterozygous women ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES skin is hyperextensible, also known as Edward's fragile & prone to trauma syndrome joints are hypermobile (contortionist) ex. kyphoscoliosis CHROMOSOMAL DISORDERS A normal female 46, XX karyotype is pictured here. It is uncommon for fetuses with Trisomy 18 to survive, Cells must first be grown so the incidence is only 1 in culture, then stimulated in 8000 live births. to divide. Trisomy 21 is an example in which the fetus may survive to term and beyond The overall incidence is 1 in 1000 live births increases in incidence with It is rare for babies to increasing maternal age, survive for very long if particularly over age liveborn because of the 40. multitude of anomalies that are usually present. The karyotype here demonstrates a female trisomy 13 (47, XX, +13) also known as Patau's syndrome This is an example of a male w/ trisomy 21 (47, XY, +21) also known as Down Syndrome This karyotype demonstrates trisomy 18 (47, XY, +18) ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES It is rare for fetuses with This is Klinefelter's Trisomy 13 to go to term, syndrome with a 47, XXY so it occurs in only 1 in karyotype. This is 6000 live births relatively common (about 1 in 500 males) Cyclopia (single eye) with a proboscis (the projecting tissue just above the eye). Affected males are usually This is monosomy X normal, though they may be /Turner's syndrome tall and have small (karyotype 45, X) testes. Infertility results from absent sperm. About half have gynecomastia. CONGENITAL MALFORMATIONS Omphalocele contains several loops of the small intestine. women with Turner's Syndactyly which several syndrome can live fingers are fused into one relatively normal lives, large digit. though they are unable to Sirenomelia from "siren" or bear children. "mermaid" because of the characteristic fusion of A feature of many the lower extremities that chromosomal abnormalities results from a failure of is fetal hydrops (hydrops normal vascular supply from fetalis) in which the soft the lower aorta in utero. tissues are markedly edematous and body cavities Thoracopagus - heart and filled with effusions. liver and several other ERES, TRACI ANNE SAN ANDRES - L2 LESSON 8 GENETIC DISORDERS AND CONGENITAL ANOMALIES organs are partially fused The gumma is located in and shared. the heart of a fetus. Syphilis is acquired in Meningomyelocele / Spina utero in the third Bifida (Open ang backbone trimester. at Spinal canal) Anencephaly - absence of the cranial vault in this fetus / major portion of the brain Exencephaly - cranial vault is not completely present, but a brain is present, because it was not completely exposed to amniotic fluid. Lymphangioma - there is a mass involving the left upper arm and left chest. This is an example of a granulomatous process known as a "gumma" in the case of congenital syphilis