Embryology Flashcards

1
Q

Spontaneous abortions and chromosomal defects often occur during this week

A

6-12 weeks

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2
Q

A chromosomal abnormality

Cause: extra copy of chromosome 18

Incidence: 1:5000; Infants usually die by age of 2 months.

SS: Mental retardation, congenital heart defects, low set ears, flexion of fingers

A

Trisomy 18 or Edwards Syndrome

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3
Q

A chromosomal abnormality

Cause: Three full copies of chromosome 13 in each cell in the body

Incidence: 1:5000; Most of the infants die by age 3 months

SS: Mental retardation, congenital heart defects, low set ears, flexion of fingers

A

Trisomy 13 or Patau Syndrome

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4
Q

A chromosomal abnormality

Cause: Have 47 chromosomes (XXY) and a 48 (XXXY); the more X chromosomes, more mental impairment
- Nondisjunction of XX homologue

Incidence: 1:5000 in males (detected during puberty)

SS: Sterility or hyalinization of seminiferous tubules

A

Klinefelter’s Syndrome

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5
Q

A chromosomal abnormality (most common)

Cause: Nondisjunction in male gamete
- Structural abnormality of X chromosomes
- Mitotic disjunction

Incidence: :1:2000 in female births

SS: Low hairline, short stature, shield-shaped thorax, brown spots, no menstruation

A

Turner’s Syndrome

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6
Q

A chromosomal abnormality

Cause: Random genetic error
- Female have third X chromosome (Nondisjunction or Mosaic)

SS: Girls usually have problems with speech and self-esteem, consist of two sex chromatin bodies in their cells

  • often go undiagnosed
A

Trisomy X or Triple X Syndrome (47, XXX)

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7
Q

A type of structural abnormality

Cause: Partial deletion of chromosome 5

SS: High pitched, cat-like cry, low birth weight, mental retardation, congenital heart disease, microcephaly (small head)

A

Cri-du chat Syndrome

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8
Q

A type of structural abnormality

Cause: Microdeletion occurs on the long arm of chromosome 15 (15q11-15q13).
- Inherited on maternal chromosome

SS:
→ Mental retardation, cannot speak
→ Poor motor development
→ Prolonged periods of laughter

A

Angelman’s Syndrome

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9
Q

A type of structural abnormality

Cause:
- Microdeletion occurs on long arm of chromosome 15
- Inherited on paternal chromosome

SS:
- Hypotonia, Obesity, Mental retardation, Hypogonadism, Undescended testes, Cryptorchidism

A

Prader-Willi Syndrome

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10
Q

A type of structural abnormality

Cause:
- a break or weakness on the long arm of X chromosome

Incidence:
- 1:5000, individuals with males affected more than females
- 2nd most common inherited cause of mental retardation due
to chromosomal abnormalities

SS:
- Mental retardation, large ears, prominent haw, pale blue
irises

A

Fragile X Syndrome

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11
Q

A type of structural abnormality

Cause:
- Contiguous gene syndrome inherited from parent

SS:
- Developmental delay, Seizures
- Cardiac and facial abnormalities (deletion at 17p13)
- Palatal defects, conotruncal heart defects, speech delay, learning disorder, and schizophrenia (deletion at 22q11).

A

Miller-Dieker Syndrome

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