Module 3M: Genetics Conceptual Framework Flashcards

Flashcards covering key genetics concepts, inheritance patterns, chromosomal abnormalities, and diagnostic testing methods as presented in Module 3M.

Genetics

Is the study of ways why genetic disorders occur and the study of heredity and the variation of inherited characteristics

Genetic Counseling

A communication process by which the family is supplied with the information necessary to make informed decisions about their unborn child

Genetic Disorders

Also referred as Inherited Disorders, these are disorders that can be passed from one generation to the next resulting from a disorder in gene or chromosome structure

Sex Cells

Mature reproductive cells (gametes) produced by meiosis with only $23$ chromosomes (haploid)

Somatic Cells

Body cells containing $46$ chromosomes (diploid) that multiply by mitosis

Genome

The entire complement of genes carried by a cell, such as a normal complete genome of $46XX$ (female) or $46XY$ (male)

Chromosomes

Several small, rod-shaped structures in the cell nucleus that carry all hereditary material on tightly coiled strands of DNA

Deoxyribonucleic Acid (DNA)

A double stranded helix that serves as the blueprint of life and is woven into strands to form chromosomes

Allele

Alternate forms of the same gene from a sperm and an ovum; there are typically two like genes for every trait excluding sex chromosomes

Genotype

Refers to the actual gene composition of an individual

Phenotype

Refers to the outward appearance or the expression of genes

Dominant Gene

The allele that produces an effect regardless of the state of the corresponding allele, denoted by a capital letter

Recessive Gene

A non-dominant gene that produces an effect only when it is transmitted by both parents

Homozygous

Having two like genes for a trait, such as $AA$ or $aa$

Heterozygous

Having two different genes for a trait, such as $Aa$

Carrier

An individual who is heterozygous for an abnormal gene (e.g., $Hd$) and is clinically normal

Trisomy

An abnormality in which there are three copies of a particular chromosome instead of the normal two

Monosomy

The presence of only $1$ chromosome instead of a pair

Mosaicism

The presence of two or more sets of cells that differ in their genetic make-up but arise from a single cell

Aneuploidy

Numerical chromosome errors resulting in major developmental defects, such as having $45$ or $47$ chromosomes

Gregor Mendel

Known as the Father of Modern Genetics, he created the Rule of Probability

Punnett Square

A big square divided into four little ones used to determine the probability of genetic combinations

Monohybrid Cross

A genetic cross that refers to the inheritance of one single trait only

Dihybrid Cross

A genetic cross involving two or more traits, such as $AaBb \times AaBb$

Complete Dominance

A dominance relation where the dominant allele completely masks the recessive one

Incomplete Dominance

A situation where neither allele appears to mask the other completely, such as red and white genes resulting in a pink flower

Codominance

When both alleles are fully functional and express themselves individually in the heterozygous condition, such as blood type $AB$

Huntington’s Disease

An autosomal dominant disorder affecting the nervous system characterized by dementia and chorea (rapid, jerky, involuntary movements)

Fascioscapulohumeral Muscular Dystrophy

A disorder characterized by muscle weakness and wasting in the face, shoulder blades, and upper arms

Osteogenesis Imperfecta

Also referred to as brittle bone disease, it is characterized by excessive fractures and bone deformity

Marfan Syndrome

A disorder of the connective tissue caused by defects in the fibrillin-$1$ gene, resulting in a tall, thin body and skeletal or cardiovascular issues

Waardenburg Syndrome

A group of genetic conditions causing hearing loss and changes in the colors of the hair, skin, and eyes

Cystic Fibrosis

The most fatal autosomal recessive disease, affecting both exocrine and endocrine glands with multi-system involvement

Albinism

An autosomal recessive disorder characterized by the total absence of the pigment melanin

Tay Sach’s Disease

A disease caused by the absence of an enzyme that breaks down gangliosides, leading to toxic buildup in the brain and loss of motor skills

Adrenogenital Syndrome

Enlargement of the adrenal glands due to excessive secretion of androgenic hormones, causing masculinization or feminization

Phenylketonuria

An inherited disorder that increases levels of phenylalanine in the blood, resulting in CNS damage and symptoms like musty breath

Galactosemia

A disorder affecting how the body processes galactose; milk sugars build up and damage the liver, eyes, kidneys, and brain

Limb-Girdle Muscular Dystrophy

A group of diseases causing weakness and wasting of muscles in the shoulders, upper arms, pelvic area, and thighs

Rh Factor Incompatibility

A condition occurring during pregnancy if a woman has Rh-negative blood and her baby has Rh-positive blood

X-Linked Hypophosphatemia

An X-linked dominant disorder characterized by low levels of phosphate in the blood and bowed legs

Rett Syndrome

A neurological and developmental disorder causing progressive loss of motor skills, speech, and slowed growth of the head and extremities

Alport Syndrome

An X-linked dominant disorder characterized by kidney disease, hearing loss, and eye abnormalities

Hemophilia A & B

X-linked recessive bleeding disorders resulting from congenital deficiency of coagulation protein factors VIII or IX

Color Blindness

Also known as Color Deficiency, an X-linked recessive inability to distinguish between certain colors

Fragile X Syndrome

A genetic condition causing learning disabilities and cognitive impairment, often characterized by a broad forehead and large ears

Duchenne Muscular Dystrophy

A disorder of progressive muscle degeneration due to alterations of the protein dystrophin

Polyploidy

A condition where a normally diploid cell acquires one or more additional sets of chromosomes, resulting in multiples of the haploid number

Trisomy 21

Commonly known as Down Syndrome ($47XX21$ or $47XY21$), characterized by a broad flat nose, Brushfield spots, and a peculiar crease on palms

Trisomy 18

Edwards’ Syndrome ($47XX18$ or $47XY18$), characterized by rocker-bottom feet and congenital heart defects; survival beyond infancy is rare

Trisomy 13

Patau Syndrome ($47XX13$ or $47XY13$), characterized by microcephaly and cleft lip/palate; survival beyond childhood is rare

Turner Syndrome

Also known as Gonadal Dysgenesis ($45X0$), affecting females who are typically short in stature, sterile, and have a webbed neck

Klinefelter Syndrome

A condition in males ($47XXY$) with extra X chromosomes, leading to gynecomastia, small testes, and infertility

47, XXX Females

Females who are tall for their families and have a slight reduction in IQ but maintain normal fertility

47, XYY Males

Males taller than average with a normal phenotype, sometimes associated with ADHD

Balanced Translocations

Situations where a chromosome is abnormally attached to another but the total count remains a normal $46$ with normal functioning

Unbalanced Translocations

Results from an extra chromosome being included during meiosis, leading to a total of $47$ chromosomes in the child

Inversions

Results from two breaks on a chromosome with segment inversion and reinsertion, which is non-viable to conception

Deletions

When a part of a chromosome breaks during cell division; a partial deletion on the short arm of chromosome $5$ causes cri-du-chat syndrome

Classical Karyotyping

The process where lymphocytes are identified, grown to metaphase, stained, and photographed under a microscope

Maternal Serum Screening

A noninvasive examination of maternal blood for alpha-fetoprotein, unconjugated estriol, hCG, and inhibin A to screen for defects like Down syndrome

Nuchal Translucency Screening

A first-trimester sonogram measuring fluid buildup thickness at the back of the baby's neck to identify Down or Turner syndrome

Chorionic Villi Sampling

Removal of chorion cells via a vaginal catheter for karyotyping and DNA analysis; accurate but holds significant risks

Amniocentesis

Aspiration of $20-30   mL$ of amniotic fluid through the abdominal wall, typically between the $15th$ and $20th$ week of gestation

Percutaneous Umbilical Blood Sampling (PUBS)

Also known as cordocentesis, it involves removing blood from the fetal umbilical cord at about $17$ weeks using an ultrasound-guided needle

Fetoscopy

Insertion of a fiber optic fetoscope through a small incision in the mother’s abdomen into the uterus, performed under local anesthesia

Newborn Screening

Analysis of blood from a heel prick performed $24$ to $48$ hours after birth to check for inherited conditions

Preimplantation Diagnosis

Assessment of both sperm and ova before actual implantation, applicable only to IVF procedures

Artificial Insemination by Donor (AID)

The use of a donor's sperm to impregnate a woman via injection into the uterus or cervical canal when a male partner is infertile

Surrogate Mother

A woman who agrees to be inseminated and bear a child for a couple, carrying the baby using her own uterus