Q-Bank- Genetics

Front 1

What type of genetic defects contribute to disease found in both Fragile X syndrome and Huntington disease?

Back 1

Fragile X and Huntington disease are thought to be caused by expansion of Tandem Nucleotide Repeats.

Front 2

Describe the genetic mutations associated with HNPCC (hereditary nonpolyposis colorectal cancer). What other types of cancer are these forms of mutation associated with?

Back 2

HPNCC is associated with microsatellite instability characteristic of loss of function mutations in mismatch repair genes hMLH1 and hMSH2. These mutations are also associated with hereditary endometrial cancer, ovary, stomach, and pancreatic cancer. Mismatch repair genes normally inhibit microsatellite instability, but in their absence, cancer is more possible.

Front 3

Klinefelter syndrome is associated with what chromosomal abnormality? Describe the physical and laboratory finding associated with this condition.

Back 3

Klinefelter syndrome is associated with a 47 XXY karyotype. Male hypogonadism, eunuchoid body habitis, female distribution of hair, and gynecomastia (breast buds). Low testosterone and high levels of FSH and LH are also associated.

Front 4

Microcephaly is associated with which of the 3 most commone trisomies?

Back 4

Trisomy 13, or Patau syndrome.

Front 5

Rocker bottom feet are associated with which of the 3 most common trisomies?

Back 5

Trisomy 18, or Edward syndrome.

Front 6

Epicanthal folds are associated with which of the 3 most common trisomies?

Back 6

Trisomy 21, or Down syndrome.

Front 7

Behavioral problems are most associated with which of the sex chromosome aneuploidies?

Back 7

47 XYY syndrome.

Front 8

What do Duchenne's Muscular Dystrophy, Lesch-Nyhan disease, Hemophilia, and Red-Green color blindness all have in common?

Back 8

They are inherited X-linked recessive conditions.

Front 9

Consumption of Fava beans have been associated with Mediterranean populations that have a prevalence of what genetic mutation?

Back 9

In Mediterranean populations, G6PD deficiency-associated hemolysis may occur in persons who eat a meal of Fava beans as a result of the oxidant injury initiated by the beans. Several hours after the meal, the individual may develop hemoglobinuria and peripheral vascular collapse secondary to intravascular hemolysis.

Front 10

What is the genetic defect associated with Prader-Wili syndrome? What are the symptoms that a patient with Prader-Wili syndrome will display?

Back 10

Prader-Wili syndrome involves a deletion from the paternal chromosome region within 15q11.2. In normal individuals, the methylation pattern at this location would be heterozygous, one allele (maternal) methylated and the other (paternal) nonmethylated. A child with Prader-Wili due to microdeletion at 15q11.2 would be hemizygous for the methylated allele. Patients with Prader-Wili are characterized by hypotonia and poor feeding in infancy, development of hyperphagia and obesity in childhood, delayed psychomotor development (late walking), hypogonadism, and, often, significant behavior problems.

Front 11

Explain the etiology of Cri-du-chat syndrome. Briefly describe signs and symptoms associated.

Back 11

Cri-du-chat often results from a terminal deletion of 5p. Children with Cri-du-chat have microcephaly, wide-set eyes, and significant mental retardation. There is also an associated high-pitched, monotonic cry.

Front 12

Kartagener syndrome is caused by defective ciliary function which in the adult can lead to bronchiectasis, and sinusitis. What special anatomical findings are present?

Back 12

Situs inversus totalis, with reversal of the thoracic and abdominal organs, which may be due to the fact that migration of some embryonic cells during development appears to be dependent on ciliary function.

Front 13

Describe the key features of Kawasaki disease. What type of disease is it and what are its associated symptoms?

Back 13

Kawasaki disease is characterized as a segmental necrotizing vasculitis that often occurs in the coronary arteries. Patients present with fever, erythema, and a maculopapular rash, and may have coronary artery aneurysms as sequela.

Front 14

What are the main sequela associated with Turner (45, X) syndrome?

Back 14

Patients with Turner syndrome have short stature, webbed necks, and a shield chest, and often present with coarctation of the aorta.

Front 15

What causes Androgen insensitivity syndrome? What is the genotype of an individual with this syndrome? What are the sequela associated?

Back 15

Androgen insensitivity syndrom is caused by an androgen-receptor defect. These patients have a normal male genotype (46, XY), normal female phenotype, abdominal/inguinal undescended testes, short vagina, and absence of ovaries and uterus. The most common cause is a mutation in the anrogen receptor (AR) gene the renders the AR inactive.

Front 16

What do defects of Alpha-reductase in an infant produce?

Back 16

Defects in alpha-reductase are the cause of genital defects in an individual with a normal male genotype (46, XY) that result in hypospadias and poor development of the male external genitalia.

Front 17

At what stage of Meiosis does recombination via crossing over occur?

Back 17

Recombination by crossing over occurs during Prophase of Meiosis I.

Front 18

Which Meiosis (MI or MII) contains a step where DNA replication occurs?

Back 18

Meiosis I phase contains a step where DNA replication yields double-stranded chromosomes. Meiosis II has no DNA replication step.

Front 19

How is the diagnosis of Fragile X syndrome made?

Back 19

The diagnosis of Fragile X syndrome is based on the molecular analysis of the length of CGG repeats in the FMR-1 region.

Front 20

Describe the mode of inheritance of Neurofibromatosis (or Reckinghausen disease).

Back 20

This is an autosomal dominant disorder with high penetrance, but variable expressivity.

Front 21

What are the three major features of Neurofibromatosis?

Back 21

1) Multiple neural tumors anywhere on the body
2) Numerous Pigmented Cutaneous lesions (cafe au lait spots)
3) Pigmented Iris Hamartomas (Lisch nodules)

Front 22

In Neurofibromitosis, what are the tumors due to? What gene might be invovled and what is the treatment?

Back 22

Tumors are the result of the proliferation of fibroblasts or Schwann cells in the peripheral nerves. This is possibly due to Ras inactivation. There is no treatment, except for surgical resection of the symptomatic tumors.

Front 23

What is the most common inherited Neuropathy? Which nerve in particular is most affected?

Back 23

Charcot-Marie-Tooth disease, or Sensory motor neuropathy Type I is the most common inherited neuropathy. Here, there is damage to the deep peroneal nerve, resulting in wasting of the muscles of the anterior compartment of the lower limb. The patients are children and are generally described as being clumsy. They fall frequently, sustaining injuries to their knees and ankles.

Front 24

What type of shunts are Atrial Septal Defects? Are they L to R or R to L? Do they lead to cyanotic or non-cyanotic conditions?

Back 24

ASD's are L --> R shunts and are NON-cyanotic conditions.

Front 25

In the inheritance of multifactorial traits, would the risk of a second child being affected be higher or lower than the risk of the general population?

Back 25

In the inheritance of multifactorial traits, such as cleft lip/palate, the risk of the second child being affected if the first child was, would be higher than the risk in the general population, but lower than the risk if the traits were determined by strict mendelian genetics.

Front 26

What type of infection can be seen associated with Duchenne MD?

Back 26

Pulmonary infection.

Front 27

Does Duchene MD involve an altered dystrophin protein or the absence of the dystrophin protein? How is this disease inherited?

Back 27

DMD involves the absence of the dystrophin gene and is inherited in an X-linked recessive manner.

Front 28

What are two diseases that are caused by the expansion of trinucleotide repeats?

Back 28

Fragile X syndrome and Huntington disease.

Front 29

What is the hallmark of a mitochondrial inheritance pattern? Name a disease that falls into this category.

Back 29

Leber's hereditary optic neuropathy is an example of a disease with a mitochondrial inheritance pattern. The hallmark of this pattern is matrilineal inheritance, where all of the children of an affected woman will be affects since they've all received mitochondrial genes only form the female parent.

Front 30

Neurofibromatosis, Ehlers-Danlos syndrome, Huntington's disease, and Osteogenesis imperfecta are all examples of diseases that have what mode of inheritance?

Back 30

Autosomal Dominant.