Patterns Of Inheritance

Question 1

New Mutations

Answer 1

Achondroplasia 90%
NF type 1 50%
Marfan
Rett syndrome 99%

Dominant disease
Recurrence in siblings is low
Occurrence for offspring is 50%

Question 2

Somatic Mosaicism

Answer 2

McCune-Albright syndrome

Mutations after fertilization

Question 3

Germaine mosaicism

Answer 3

osteogenesis imperfecti

Mosaic germline cells, passed to offspring

Question 4

Delayed age of onset

Answer 4

Huntington

Hemochromatosis

Question 5

Reduced penetrance

Answer 5

Retinoblastoma
Fragile X syndrome

Not all who have allele or alleles express phenotype

Question 6

Variable expression

Answer 6

Wide range of phenotypes

NF1

Question 7

Pleiotropy

Answer 7

Cystic fibrosis
Diabetes
Marfan
Von Gierke disease

Affects multiple organs or aspects of physiology

Question 8

Heterogeneity

Answer 8

allelic- different mutations in same locus produce same phenotype

CF, b-thalassemia

Locus- different mutations of different loci produce same phenotype

osteogenesis imperfecti

Question 9

Genomic imprinting

Answer 9

Prayer-willi syndrome= deletion from father SNRPN
Angelman syndrome= deletion from mother UBE3A

Chromosome 15 deletion long arm

Uni parental disomy or deletion during gametogenesis (80%)

Question 10

Anticipation

Answer 10

Huntington
Myotonic dystrophy
Friedrich ataxia
Fragile X syndrome

Earlier age or more severe with each generation
DMPK myotonic dystrophy caused by expansion of trinucleotide repeat, dna pol slippage

Question 11

Consanguinity

Answer 11

Rare autosomal diseases

Question 12

Genetic burden

Answer 12

Everyone has a few bad recessive alleles