NUR 612- Genetic and Congenital Disorders Review Questions and Correct Answers

Describe three types of single-gene disorders and their patterns of inheritance. They follow mendelian inheritance patterns. Caused by a single defective or mutant gene. Can often be obtained through a family hx. Autosomal dominant (a single mutant allele is transmitted from one parent regardless of sex) Autosomal recessive (manifested when only both genes from the allele are affected- both parents are carriers but unaffected) X-linked Recessive (always associated with the x chromosome, almost always recessive. The father will pass his x on to none of his sons and to all of his daughters. The daughers then have a 50% chance of passing along that X to their offspring.) Give examples of the following: Autosomal dominant disorder Autosomal recessive disorder X-linked recessive disorder Autosomal dominant: Marfan and neurofibromatosis Autosomal recessive: PKU and Tay-Sachs X-linked recessive: Fragile X Contrast disorders due to multifactorial inheritance with those caused by single-gene inheritance. Caused by multiple genes and environmental factors. The exact number of genes is not known. Traits do not follow a clear-cut pattern of inheritance. Disorders can be expressed during fetal life and be present at birth, or expressed later in life. List some examples of multifactorial inheritance disorders Cleft lip or palate Clubfoot Congenital dislocation of the hip Congenital heart disease Pyloric stenosis Urinary tract malformation Describe disorders of chromosomal breakage and rearrangement on autosomes and sex chromosomes. Describe disorders that involve change in number of chromosomes. Disorders of chromosomal breakage are involve structural changes to chromosomes involve deletion or addition of genetic material. This may involve moving genetic material from one chromosome to the other. A change in chromosome number is ANEUPLOIDY. Monosomy is the presence of only one chromosome of a pair. Polysomy refers to the presence of more than two chromosomes. Trisomy 21 Downs Syndrome Risk: increases with maternal age Cause: 95% are due to nondisjunction of chromosome 21 (robertson translocation can make this more likely) Presentation: intelectual disability, facial features, common health problems Diagnosis: by physical characteristics, prenatal testing, nuchal translucency via US Monosomy X Turner Syndrome. Can be all or part of the X chromosome. Risk: One in 2500 live births Presentation: Short stature with normal proportions, infertility, cardiac disorders, physical characteristics Diagnosis: often not until late childhood or adolescence Treatment: Growth hormone therapy, estrogen therapy for sex characteristics