Statistics by Disease

Question 1

Turner Syndrome:

• Percentage of Conceptuses
• Percentage of Live births

Answer 1

2% of conceptuses

1/2500 live births

Question 2

Kleinfelter Syndrome

• Rate of live births
• Rate of infertility
• Rate of High level infertility

Answer 2

1/500 male births
1/50 infertility
1/7 high infertility

Question 3

Down Syndrome

• Rate of live birth
• Rate of conceptus fatality
• Rate of three major causes/manifestations

Answer 3

-1/700 live births
-75% fetally fatal
-94% Maternal Non-disjunction
1-3% Mosaics
3-4% Translocation

Question 4

Edwards Syndrome

• Rate of live births
• Rate of conceptus fatality
• Recurrence risk
• Average age of fatality

Answer 4

-1/7500
-95% fetally fatal
-1% if de novo, 2% if parent translocon carrier
-75% die by 3 mo of age
90% die by 1 yr of age

Question 5

Patau Syndrome

• Rate of live births
• Rate of conceptus fatality
• Recurrence risk
• Average age of fatality

Answer 5

-1/10-12000 live births
-95% fail to reach term-
-1% if de novo, 2% if parent translocon carrier
-75% die by 3 mo of age
95% die by 3 yr of age

Question 6

Down Syndrome

• Recurrence with Robertsonian Translocation
• Recurrence with Robertsonian Isotranslocation

Answer 6

Recurrence risk with the mother having translocation is about 16%
Recurrence risk with the father having translocation is about 5%
Recurrence risk with a Robertsonian Isotranslocation is 100%, unless it occurs with a mitotic nondisjunction (i.e. a mosaic) where it is 1%

Question 7

Repeat differential in Huntingtin Gene:

• Normal
• Abnormal

Answer 7

Normal repeats =10-30

Abnormal repeats = 36-121

Question 8

Heterozygous load of hemochromatosis

Birth rate of patients with hemochromatosis

Answer 8

8-11%

1/300

Question 9

Ratio of males to females in non-fatal X-linked dominant diseases

Answer 9

1:2

Question 10

Percent of Retts Syndrome cases who are male

Answer 10

~0% (lethal to non-Kleinfelter’s males)

Question 11

Percent of Inconscientia Pigmenti cases who are male

Answer 11

~0% (lethal to non-Kleinfelter’s males)

Question 12

Odds of mother being a carrier for an X-linked condition if she produces a male with poor fitness

Answer 12

2/3

Question 13

Point at which a germline mosaic considered

Answer 13

Two affected males, but mother is a negative carrier

Question 14

Number of CAG repeats in Myotonic Dystrophy:
Normal
Mild
Severe

Answer 14

• 5-30 repeats normal
  
  • 50-80 repeats mild affect
  • 2000+ repeats severe affect

Question 15

Risk of inheriting Leben Hereditary Optic Neuropathy from each parent

Answer 15

Dad–0%

Mom–Variable, but high (she may have normal mitochondria that exhibit heteroplasmy or homoplasmy in her germ line)

Question 16

Velo-cardio-facial syndrome

-Rate of de novo versus inherited mutations

Answer 16

93% of cases are de novo 7% of cases are inherited

Question 17

Angelman syndrome

-Rates of inheritance

Answer 17

70%= The loss of the mother’s contribution of the Angelman gene via deletion
7% by paternal unidisomy
3% by inappropriate imprinting of mother’s copy
10% by activated silencers in mother’s copy
10% by mutations in mother’s copy

Question 18

Tuberous Sclerosis

-Rates of de novo versus inherited mutation

Answer 18

66% de novo

34% inherited

Question 19

Achondroplasia-
Rate of de novo mutation
Survival chances of a homozygous dominant

Answer 19

80% de novo

0% of homozygous dominant cases survive

Question 20

Williams syndrome

Rate of de novo mutation

Answer 20

99% of cases are de novo

Question 21

Wolf-Hirschhorn Syndrome
Rate of de novo mutation
Rate of inheritance from translocon parent

Answer 21

85% of cases are de novo deletion

15% of cases are inherited unbalanced translocations

Question 22

Cri-du-chat
Rate of de novo mutation
Rate of inheritance from translocon parent

Answer 22

85% of cases are de novo deletion

15% of cases are inherited unbalanced translocations

Question 23

Marfan Syndrome

Rate of de novo mutation

Answer 23

25%