NUR 418 Genetics and Genomics in Maternal and Newborn Care

Aneuploidy

chromosomal anomaly resulting from too few or too many of a particular gene

Multifactoral disorders

Affected by more than one gene and how they interact with the environment and lifestyle

When can anomalies occur

prenatally, postnatally, or prior to implantation of a fertilized ovum

trisomy

three copies of a certain homologous chromosome

What are a few more serious disorders and defects that occur with trisomy 21

conditions affecting vision and hearing, sleep apnea, heart malformations

what is an infant with down syndrome and a CHD at risk for

feeding problems, swallowing difficulties, and aspiration

What are the most prevalent chromosomal disorders

sex chromosome anomalies

Hallmark signs of sex chromosome anomalies

aneuploidy, structural anomalies, and sections of sex chromosomes

Turner Syndrome (girl or boy?)

girl, missing second sex chromosome from dad, only has X

Turner syndrome characteristics

short stature, skeletal anomalies, infertility/ovarian dysfunction, heart or kidney structural defects, most typical cause of primary amenorrhea

Klinefelter Syndrome (girl or boy?)

Boy, XXY

Klinefelter syndrome characteristics

tall, enlarged breasts, small testicles, distribution of body hair similar to that of females

Triple X Syndrome (girl or boy?)

Girl, XXX

Triple X Syndrome characteristics

tall, learning disabilities, muscular weakness, kidney defects

XXY Syndrome (girl or boy?)

Boy

XXY Syndrome characteristics

learning disabilities, delayed speech, language, and motor skill development, behavioral and emotional issues

Multifactoral inheritance

More than 1 gene/contributing causes involved (T2D, Heart disease, high BMI)

Unifactorial inheritance

single gene disorders

Autosomal Dominant Inheritance

Only need 1 of gene to be expressed, Huntingtons Disease and Marfans Syndrome

Autosomal Recessive Inheritance

Need 2 copies to be expressed and do not impact every generation of a family, Cystic Fibrosis, Sickle cell disease

Inborn error: phenylketonuria

body accumulates phenylalanine, accumulates in brain and causes cognitive defects

X-Linked Dominant

Males are more vulnerable and have more severe manifestations than females. Fathers cannot pass on X-linked features to their sons

X linked recessive

Males are more vulnerable; females have to have the mutation on both copies. Fathers do not pass this. Hemophilia is an example

Preconception carrier screening

done before pregnancy, can detect whether a person has the gene for certain genetic conditions. Can determine whether the client seeking conception or their partner has a chance of passing along a genetic condition to their offspring

If you are in a high risk group, should you get a screening or a diagnostic

Diagnostic because it will show if you have the condition FOR SURE

what are conditions commonly screened for

cystic fibrosis, sickle cell, tay-sachs, Huntington's, and various hemoglobinopathies

target carrier screening

The client knows their history and gets this before becoming pregnant to see if they are a carrier for specific conditions.

Expanded carrier screening

Many conditions may be detected using a single sample; these examinations concentrate more on serious diseases that manifest early in childhood

Which clients are at risk for genetic anomalies

clients over the age of 35

Which clients are at risk for having a newborn with a genetic disorder

any client with a personal or familial history of a genetic disorder, and clients who had a previous spontaneous abortion or fetal demise

Cell-free DNA testing

blood sample from pregnant person tested for presence of maternal and fetal DNA to screen for conditions arising from chromosomes.

When is Cell free DNA testing done

as soon as 10 weeks up until the time the client gives birth

what are most common disordes screened for in Cell Free DNA screening

Trisomies

Nuchal Translucency Testing/Screening

thickness of fluid pocket at back of fetus neck measured during ultrasound. screening tool for detection of chromosomal and genetic anomalies

when is nuchal translucency testing done

11-13 weeks

What conditions are common for an unexpected nuchal translucency

Trisomy 21, or another aneuploidy, is also associated with skeletal, abdominal, and cardiac anomalies.

chronic villus sampling

DIAGNOSTIC! uses placental biopsy to perform genetic testing and provides opportunity for early detection

when to get chronic villus sampling

10-13 weeks

Risks of performing CVS

Risky to perform on clients taking anticoagulants, CVS increases risk of fetal hemolytic disease if the fetus is Rh positive and the mother is Rh negative

What are the tests used in the second trimester

quad screen and anatomy ultrasound scan

When is the quad screen performed

between 15 and 22 weeks gestation

what risks does the quad scan indicate

trisomy 21, neural tube defects and trisomy 18

Clients who are recommended to have a quad screen

family hx of congenital or genetic anomalies, those over 35, and clients taking medications with known teratogenicity

When should an anatomy scan be performed

between 18 and 22 weeks gestation

why do clients get an anatomy scan

can identify fetal sex and growth. also looks for physical problems in fetus body and organs

Amniocentesis

DIAGNOSTIC! Used to confirm or rule out various inherited or genetic concerns. More dangerous than other tests

Are health disorders discovered early in life through newborn screening treatable?

Yes

How is newborn screening performed

collecting a blood sample, performing a hearing test, and cardiac testing via oxygen saturation measurements

what things do newborn screening tests screen for?

Endocrine and hemoglobin disorders. Less common disorders screened for are organic acid metabolism disorders, fatty acid oxidation disorders, and amino acid metabolism disorders (such as PKU)

What happens if a newborn screening test comes back positive?

A diagnostic test will be recommended to confirm or rule out the specific disease

consanguinity

The sharing of common ancestry with another individual.

Pedigree

A representation of an individual's known ancestors and their biological traits.