FTM Exam 1 Diseases

Question 1

Turner’s Syndrome

Answer 1

A single X chromosome due to a miosis I non-disjunction event. Father contributes no sex chromosomes.

Question 2

Kleinfelter’s Syndrome

Answer 2

XXY, due to a meiosis I non-disjunction event.

Question 3

XYY Syndrome

Answer 3

XYY, due to a meiosis II non-disjunction event

Question 4

Triple X-syndrome

Answer 4

XXX, due to a meiosis II non-disjunction event. However, Barr bodies still form on 2 of the X chromosomes.

Question 5

Myotonic dystrophy

Answer 5

Autosomal dominant inheritance pattern. DMPK mutation. Caused by aberrant triplet repeats.

Question 6

Achondroplasia

Answer 6

Autosomal dominant inheritance pattern. FGFR3 mutation. Gain of function mutation.

Question 7

Neurofibromatosis Type I

Answer 7

Autosomal dominant inheritance pattern. NF-1 mutation (allelic heterogeneity). NF-1 is a tumor suppressor.

Question 8

Marfan Syndrome

Answer 8

Autosomal dominant inheritance pattern. Fibrillin-1 gene defect-Dominant negative mutation.

Question 9

Osteogenesis imperfecta

Answer 9

Autosomal dominant inheritance pattern. Mutated collagen gene(s)-COL1A1 or COL1A2. Haploinsufficiency (Type I).

Question 10

Familial hypercholesterolemia

Answer 10

Autosomal dominant inheritance pattern. LDL receptor or ApoB mutation. Haploinsufficiency.

Question 11

Huntington’s Disease

Answer 11

Autosomal dominant inheritance pattern. CAG repeats in Huntingtin protein causes aggregation of it in neurons, leading to

Question 12

Acute Intermittent porphyria

Answer 12

Autosomal dominant inheritance pattern. Enzyme deficiency of porphobilinogen deaminase. Haploinsufficiency.

Question 13

Cystic Fibrosis

Answer 13

Autosomal recessive inheritance pattern. CFTR Mutation. Exhibits allelic heterogeneity and variable expression.

Question 14

Sickle Cell Anemia

Answer 14

Autosomal recessive inheritance pattern. Caused by a mutation in Beta-globin gene.

Question 15

Phenylketonuria

Answer 15

Autosomal recessive inheritance pattern. Caused by a deficiency of phenylalanine hydroxylase.

Question 16

Tay-Sachs disease

Answer 16

Autosomal recessive inheritance pattern. Caused by a deficiency of hexosaminidase A.

Question 17

Congenital Deafness

Answer 17

Autosomal recessive inheritance pattern. Multiple genes.

Question 18

Hemochromatosis

Answer 18

Autosomal recessive inheritance pattern. Mutations in HFE gene, an iron metabolism gene. Allelic heterogeneity and variable expression in each patient.

Question 19

Alkaptonuria

Answer 19

Autosomal recessive inheritance pattern. Mutation in HGD gene which codes for homogentisate 1,2-dioxygenase.

Question 20

alpha-1 Antitrypsin Deficiency

Answer 20

Autosomal recessive inheritance pattern. Deficiency in alpha-1 antitrypsin

Question 21

Xeroderma pigmentosum

Answer 21

Autosomal recessive inheritance pattern. Caused by a mutation in one of many nucleotide excision repair enzymes, meaning no repair mechanism for UV damage.

Question 22

Severe Combined Immunodeficiency (Adenosine Deaminase Linked)

Answer 22

Autosomal recessive inheritance pattern. Adenosine deaminase deficiency, due to mutation.

Question 23

Duchenne’s Muscular Dystrophy

Answer 23

X-linked recessive inheritance pattern. Mutation of the dystrophin gene, but milder phenotype. Appears in heterozygous women due to X inactivation and some men.

Question 24

Becker’s Muscular Dystrophy

Answer 24

X-linked recessive inheritance pattern. Mutation of the dystrophin gene, but a milder phenotype. Appears in heterozygous women due to X inactivation and some men.

Question 25

Glucose 6-Phosphate DH deficiency

Answer 25

X-linked recessive inheritance pattern. Abnormally low levels of Glucose 6-phosphate dehydrogenase. This predisposes RBCs to oxidative damage due to glutathione.

Question 26

Hemophilia A and B

Answer 26

X-linked recessive inheritance pattern. Deficiency of clotting factor VIII, resulting in high tendency to bleed.

Question 27

Lesch-Nyhan Syndrome

Answer 27

X-linked recessive inheritance pattern. Deficiency of hypoxanthine-guanine phosphoribosyl transferase (HGPRT)

Question 28

Red-Green color blindness

Answer 28

X-linked recessive inheritance pattern. Defect in cone genes on X chromosome

Question 29

X-Linked SCID

Answer 29

X-linked recessive inheritance pattern. Defect in gamma chain of IL2RG, an interleukin receptor.

Question 30

Rett Syndrome

Answer 30

X-linked recessive inheritance pattern. Germline mutation in MECP2 gene. Mother would be a germline mosaic.

Question 31

Incontinentia pigmenti

Answer 31

X-linked dominant inheritance pattern. Germline mutation or affected parent with mutated IKBKG gene.

Question 32

Vitamin D-resistant Ricket’s

Answer 32

X-linked dominant inheritance pattern. Caused by a mutation in the PHEX gene, which regulates FGF23.

Question 33

Charcot-Maire-Tooth Disease

Answer 33

Can have either AD, AR or XR inheritance pattern. Exhibits locus heterogeneity, as multiple genes can contribute to CMT.

Question 34

Familial Breast Cancer

Answer 34

Autosomal recessive inheritance pattern. Usually BRCA1/2 mutations (about 50% of the time), causes HD repair defect.

Question 35

MELAS

Answer 35

Mitochondrial inheritance pattern. MT-TL1 (a mitochondrial tRNA) mutations cause 80% of cases. NADH DH is other 20%

Question 36

Leber’s Hereditary Optic Neuropathy

Answer 36

Mitochondrial inheritance pattern. Mutations in MT-ND1, MT-ND4, MT-ND4L, & MT-ND6 cause this disease. These genes code for NADH dehydrogenase subunits for ox. phos.

Question 37

MERRF

Answer 37

Mitochondrial inheritance pattern. 80% of cases caused by mutation in the mitochondria tRNA-lysine.

Question 38

Retinitis Pigmentosa

Answer 38

Multiple patterns of inheritance with multiple genes. In class, we talked about ROM1 and peripherin.

Question 39

Prader-Willi Syndrome

Answer 39

Loss of SNRPN gene function. SNRPN is epigenetically silenced on chromosome 15 in the maternal genome. Thus, inheriting two maternal copies of chromosome 15 or a microdeletion of the paternal chromosome 15 causes PWS.

Question 40

Angelman Syndrome

Answer 40

Loss of UBE3A gene function. UBE3A is epigenetically silenced on chromosome 15 in the paternal genome. Thus, inheriting two paternal copies of chromosome 15 or a microdeletion of the maternal chromosome 15 causes AS.

Question 41

Fragile X Syndrome

Answer 41

Caused by a CGG triplet repeat in the FMR1 gene on the X chromosome, which makes X chromosome look “fragile” toward the telomere end of the P arm.

Question 42

Friedreich’s Ataxia

Answer 42

Autosomal recessive inheritance pattern. Caused by a GAA expansion in an intron of the FXN gene, leading to reduced expression of the mitochondrial metabolism protein frataxin.

Question 43

DiGeorge Syndrome

Answer 43

Caused by a microdeletion of 22q11.2. Most cases are novo, but if inherited, it’s autosomal dominant.

Question 44

Purine Nucleoside Phosphorylase Deficiency (PNP Deficiency)

Answer 44

Autosomal recessive inheritance pattern. Caused by PNP mutation. Very rare. Only 33 documented cases in U.S.

Question 45

Gout

Answer 45

Hyperuricemia, leading to acute arthritic joint inflammation caused by deposition of uric acid crystals.

Question 46

Orotic Aciduria (Pyramidine Synthesis Pathway)

Answer 46

UMP Synthase deficiency, leading to a buildup of orotate.

Question 47

Burkitt’s Lymphoma

Answer 47

Translocation of cMyc to antibody promoter in B cells, causing uncontrolled growth of B cells.

Question 48

Hutchinson-Gilford Progeria Syndrome is due to:

Answer 48

Lamin A mutation

Question 49

Describe the nuclear lamina

Answer 49

Thin, sheet-like meshwork beneath the inner nuclear membrane
-Scaffold for nuclear envelope, chromatin & nuclear pores, Disassembles during mitosis