Genetics and Genetic testing
Terms in this set (29)
chromosomal makeup of an individual. 46 chromosomes.
physical appearance of an individual
refers to total number of chromosomes
refers to total number of specific chromosome
abnormal number of chromosomes
3 copies of a specific chromosome
3 complete sets of chromosomes
failure of the centromere to split during cell division- results in two copies of chromosomes go to one daughter cell and no copies go to the other daughter cell. can be maternal nondisjunction or monosomy
type of nondisjunction. common cause of trisomy. cause unknown, but strongly linked to advancing maternal age
type of nondisjunction. may be caused by either maternal or paternal nondisjunction.
genetic trait that only requires one copy of the abnormal gene to be manifested. (adult polycystic kidney disease)
genetic trait that requires two copies of the abnormal gene to be manifested. (cystic fibrosis)
medical genetics. genetic trait that is manifested in males but inherited from their mothers. males with defect pass to their daughters who will be carriers. daughters then pass to their songs who manifest the trait. Ex: male pattern baldness, aqueduct stenosis
abnormality that requires interaction of one or more genes and environmental factors to occur. Ex: juvenile diabetes
genetic mutation/chromosomal abnormality that only occurs in part of the cells of an individual
type of altered chromosome structure. part of the chromosome is lost. rarely results in a ring chromosome
type of altered chromosome structure. addition of extra genetic information to the chromosome. occurs during meiosis
type of altered chromosome structure. part of chromosome is rearranged within itself. does not result in loss of genetic information, but the code is scrambled. often no abnormality in parent, but can show up in children.
type of altered chromosome structure. chromosome breaks and the broken portion is transferred to another chromosome. does not always result in anomalies.
the 22 non-sex chromosomes. each individual has 22 pairs
autosomal dominant transmission
the trait or condition is manifested when only one copy of the gene is present. when only one parent has this gene there is a 50% chance that each child will exhibit that gene
autosomal recessive transmission
two copies of the gene must be present for the trait or condition to be manifested. if both parents manifest the trait the children will also manifest that trait. parents who are heterozygous for that trait are carriers but do not exhibit the condition
inheritance. genes located on the X chromosome controls some traits or conditions besides being female. may be dominant or recessive. recessive is more common.
inheritance. transmission. conditions occur as combination of genetic and non-genetic causes. conditions run in families (genetic predisposition) but no identifiable pattern of transmission is present
chorionic villous sampling
genetic testing. remove sample of the chorionic villi- early placental tissue- to do genetic analysis; also detect metabolic/biochemical disorders, hemoglobinopathies. only performed between 9-12 weeks. gets results in 24-48 hours. earlier test and results allow more options. ultrasound guidance used for procedure.
genetic testing. small camera is placed in the uterus to directly view the embryo/fetus from outside the chorionic membrane, usually during the first trimester. not widely used. can detect fetal anomalies.
cordocentesis (percutaneous umbilical blood sampling)
ultrasound guided procedure where a needle is inserted into the umbilical vein within the umbilical cord to obtain a sample of fetal blood. fetal cells can be used to get karyotype results within 2-3 days. beneficial to get more detailed information. can also be used to get information more rapidly when an anomaly is discovered. now mainly done for fetal transfusions.
genetic testing. withdrawal of amniotic fluid for analysis. now done with sonographic guidance. FISH technique can be used to get analysis for most common chromosomal anomalies in 24 hours. should be done between 15 and 20 weeks. indications: advanced maternal age, history of child with chromosomal anomalies, abnormal AFP, abnormal quad screen, anomaly detected.
the needle must be place ----- during needle placement to the sound beam so that the entire length of the needle can be seen
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