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Flashcards in Genetics Deck (96)
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1
Q

Dysmorphology

A
  • Aspect of clinical genetics that involves the syndrome diagnosis in children who have unusual facial features, congenital malformations and often have associated cognitive and motor delays.
  • >3500 syndromes
  • Some are instinctive recognized by past experience
  • Others involve pieces of puzzles
2
Q

Blaschko’s Lines

A

lines of embryologic ectodermal development

3
Q

Chromosomal Disorders

A
  • Part or whole chromosome is missing or duplicated
  • Example: Down syndrome
  • Tested by Karyotype
4
Q

•Microdeletion or microduplication syndromes

A
  • A very small piece of chromosome is missing or duplicated
  • Cannot be seen on karyotype
  • Examples: DiGeorge, velocardiofacial; williams syndrome
  • Fish/ Array comparative hybridization (ACGH)
5
Q

Single Gene Disorders

•Dominant (AD), recessive (AR), X-linked

A
  • A mutation in a single gene causing a disorder
  • AD: Marfan syndrome, neurofibromatosis, type 1
  • AR: cystic fibrosis, sickle cell disease, Tay Sachs disease
  • X-linked: Duchenne Muscular dystrophy
  • Testing: Mutation analysis, DNA sequencing and or deletion testing
6
Q

Triple Repeat Disorders

A
  • Trinucleotide repeats in certain genes exceeding the normal, stable threshold which differences for each gene.
  • Results may be interference of the normal gene or gene product
  • Example: Fragile X, Huntington disease
  • DNA tests for number for repeats
7
Q

Multifactorial Disorder

A
  • A combination of genetics and environment
  • Examples: Cleft lip and palate; clubfeet; pyloric stenosis
  • No current testing available
8
Q

Epigenetic Disorder

A
  • Changes are not in the sequencing but in the expression of the DNA
  • Examples: Prader Willi; Beckwith-Weidman syndrome
  • Testing by Methylation analysis
9
Q

Receiving a genetic dx helps you to

A
  • Informs reproductive decision
  • Preventative strategies
  • Explanation of what you can do
  • Massive parallel sequencing will explain what is causing the patient’s problem
  • Take an 11 year old who has a sudden cardiac arrest.
  • Genome would tell the patient’s need for implant
10
Q

Sequences

A

•A defect occurs and subsequent development is abnormal

11
Q

•VACTERLS Association

A
  • V – vertebral anomalies / dysgenesis, vascular anomalies
  • A – anal atresia
  • C – Cardiac anomalies
  • T – trachea-esophageal (T-E) fistula
  • E – esophageal atresia
  • R – renal anomalies, radial dysplasia
  • L – Limb anomalies
  • S - Single umbilical artery
12
Q

CHARGE

A
  • C” for coloboma
  • “H” for heart defects
  • “A” for atresia choanal
  • “R” for retardation of growth and development
  • “G” for genitourinary problems
  • “E” for ear abnormalities
13
Q

Complexes

A

•Abnormalities in adjacent structures

14
Q

•Goldenhar syndrome

A
  • Affects one side of the face only. :
  • Partially formed or totally absent ear (microtia)
  • Chin may be closer to the affected ear
  • One corner of the mouth may be higher than the other
  • Benign growths of the eye
  • Missing eye
15
Q

•Major Anomalies

A

Easily identified

Involve easily identified malformations

16
Q

•Congenital abnormalities

A
  • Present at birth
  • Does not imply cause
17
Q

Minor Anomaly

A
  • Physical difference that occur in fewer than 4% of the population
  • More commonly in areas that are more variable and complex: face, hand
  • 70% in these two area
18
Q

Normal phenotypic variant

A

•Present in 4% or more of the population

19
Q

•Some minor anomalies are markers for occult major malformations

A
  • Sacral tuft of hair or deep sacral dimple: associated with occult spinal dysraphism
  • Many genetic syndromes are specific patterns of minor anomalies occurring together
  • Specific minor abnormalities of face, hands, feet-Down syndrome
20
Q

Assess for Major malformation when…

A

•Three or more minor anomalies increased risk of having major malformation

21
Q

Most common external anomalies

A

Face

Auricle

Hands

Feet

22
Q

Normal Phenotypic Variant (10)

A
  • Saddle (mildly upturned nose)
  • Mild to moderate in bowing of lower leg
  • Sacral dimple, not deep
  • Mild syndactyly of second and third toes
  • Toenail hypoplasia in the newborn
  • Hydrocele of the testicle
  • Epicanthal folds
  • Unilateral epicanthal fold is indicative of torticollis
  • Slanting of the palpebral fissures
  • Brushfield spots (20% of normal newborns)
23
Q

Frequent newborn findings

Stork bite

A

•Fine non-elevated pink to red capillary hemangioma at nape of neck, over central forehead and eyelids and in the lumbosacral region

24
Q

Skull Physical Assessment findings

A
  • Asymmetrical head or face
  • Brachycephaly
  • Flattened occiput
  • Fontanels too large or small
  • Overlapping sutures
25
Q

Facial Proportions

Mandible/Maxilla

A
  • Micrognathism: small mandible
  • Retrognathism: Receding
  • Prognathism (Projection of jaw beyond that of forehead)
26
Q

Ocular hypertelorism

A

•A low nasal bridge will give the appearance of hypertelorism

27
Q

Telecanthus

A

consequence of lateral displacement of the inner canthi

28
Q

Minor abnormalities of the Face

A
  • Synophrys – Fused eyebrows
  • Flat bridge of nose
  • Hypotelorism
  • Anteverted nostrils
  • Epicanthal fold
  • Iris freckles
  • Upward palpebral slant (mongoloid slant)
  • Downward palpebral slant (antimongoloid slant)
  • Blue sclera
  • Epicanthal folds
  • Different eye colors
29
Q

Minor Malformations of the hair

A

•Circular pattern of hair (cowlick)

Kinky hair, brittle hair including eye brows.

30
Q

•Hair patterning (4)

A
  • Look for unusual hair pattern
  • Low set hair line
  • Widow’s peak
  • Webbed neck
31
Q

Asymmetrical Crying Facies

A
  • Higher incidence of congenital heart disease
  • Ventriculoseptal defects
  • Atrial septal defect
  • Patent ductus arteriosus
  • Tetralogy of Fallot
  • Velocardiofacial syndrome (22q11 deletion syndrome)
32
Q

Eye Distances

Mean Length in a 5 yr old

A
  • Palpebral fissure length
  • Mean length in a five year old is 2.5 cm
  • Short palpebral fissures is minor anomaly
33
Q

Magic Number for Eyes

A

10 degrees

34
Q

Slanting of Palpebral fissures

A
  • Normal Horizontal or upward slanting with an angle <10 degrees
  • Upward slanting angle >10 degrees
  • Downward slanting
  • External canthus lower than the internal canthus
35
Q

Brushfield spots

A

White spots in Iris

Heterochromia**different colors in one eye – associated with a higher risk of retinal blastoma

36
Q

Wilson Disease (Hepatolenticular Degeneration )

•Age of onset for Wilson disease

A

•between 8 years to the mid-50’s

37
Q

•Presentation of Wilson Disease

A
  • Severe liver cirrhosis.
  • Kayser-Fleischer rings
  • Deposition of copper in the cornea.

Accompanied by neurological disorder.

38
Q

Normal distance between eyes

A

One eye length

39
Q

Ear Positioning

A

more than 20 degrees, posteriorly rotated

40
Q

Minor abnormalities of the auricle region

A
  • Large ears
  • Lop ear
  • Lack of lobulus
  • Lobe crease
  • Thick helix or attached to scalp
  • Protruding ears (due to lack of development of the posterior auricular ear muscle
  • Low set ears

Ears slanted greater than 15 degrees from the perpendicular

41
Q

Preauricular Tags

A
  • Found anywhere along a line drawn from the tragus to angle of mouth
  • 1.7 per 1,000 individuals
  • Bilaterally in 6% of affected individuals
  • Autosomal dominant inheritance pattern
42
Q

Preauricular Pits

A

•Small openings at anterior margin of the helix

43
Q

Goldenhar syndrome

A
  • Look for facial asymmetry and microtia
  • Unilateral or bilateral Hemifacial Microsomia (HFM)
  • Microtia - Literally meaning “small ear”,
  • Aural Atresia - Absence of the auditory canal

Other Problems: cleft lip/palate, hearing loss, epibulbar dermoids, vertebral anomalies and organ abnormalities including kidney and heart anomalies.

44
Q

Fetal alcohol lips

A

Shallow groove

45
Q

Mouth

Physical Assessment findings

A
  • Small or large tongue (micro or macroglossia)
  • Misshapen, missing or extra teeth
  • Early loss of teeth
  • Late eruption of teeth
  • Thin upper lip
  • Cleft uvula
  • Smooth or abnormal philtrum
46
Q

Recognition of Abnormalities

A
  • Some minor anomalies run in families as a single variation
  • As high as 14% of newborns have at least one minor anomaly.
  • If there are three or more minor anomalies, there is approximately a 20% chance of a major anomaly.

Represent deformation due to altered mechanical forces affecting the development of otherwise healthy tissue

47
Q

Enamel Hypoplasia

A

•defect in tooth enamel that results in less quantity of enamel than normal

48
Q

Anodontia

A

Congenitally missing teeth

49
Q

•hypodontia

A

congenital absence of one or a few permanent teeth without any systemic disorders

50
Q

Hair – May be significant

A
  • Excess body hair
  • Hairline and hair distribution
  • Large section of white hair in front – Waardenburg Syndrome
  • Sparse or brittle hair
51
Q

5 major diagnostic criteria for WAARDENBURG

A
  • Sensorineural hearing loss
  • Iris pigmentary abnormality (two eyes different color or iris bicolor or characteristic brilliant blue iris)
  • Hair hypopigmentation (white forelock or white hairs at other sites on the body),
  • Dystopia canthorum (lateral displacement of inner canthi
  • First-degree relative previously diagnosed with Waardenburg syndrome.
52
Q

Minor criteria for Waardenburg

A
  • Skin hypopigmentation (congenital leukoderma/white skin patches(Face, trunk, or limbs - 30-36 %)
  • Medial eyebrow flare (synophrys)
  • Broad nasal root
  • Hypoplasia alae nasi
  • Premature graying of the hair (before age 30) .
53
Q

Waardenburg syndrome Diagnosis

A

Two major or one major plus two minor

54
Q

Dysmorphology Checklist

hair

A
  • Normal
  • Unusual texture
  • Sparse/alopecia
  • Low posterior hairline
  • Low anterior hairline
  • Unusual pattern extra whorls
  • Unruly, uncombable
  • White forelock
55
Q

Cornelia De Lange

A

Hairline Low

Hypertrichosis – hair sticks up

Coarse features

Eyebrows are joined

Posterior rotated ears

Developmental delay

Eyelids not right

56
Q

Postaxial

A

Ulnar side

57
Q

Preaxial

A

Radial side

58
Q

Brachydactyly

A

Abnormal digits

Most are autosomal dominant

59
Q

Minor abnormalities of the Hands

A
  • Clinodactyly (curved fingers)
  • Syndactyly (some or all fingers united)
  • hypoplastic
  • Asymmetric length
  • Camptodactyly – contracted

Malportion or disharmony in the length of particular segment of the hand

60
Q

Nail Hypoplasia

A

•Incomplete nail development

61
Q

•Clinodactyly

A

Curved or bent finger

62
Q

Palmar Creases

A
  • Formed from second to fifth month
  • Once the palmar creases are formed, unchanged throughout life
  • Single palmar crease occurs unilaterally in 4 % of general population
  • Single palmar crease occurs bilaterally in 1% of the general population
  • In Chinese population: normal phenotypic variant 16.8% of Chinese have unilateral crease
  • Carefully evaluate for other problems
63
Q

Palmar Creases

Trisomy 13

A
  • Excess of arches
  • Single palmar creases in 60%
64
Q

Palmar creases

Turner Syndrome

A

•Predominance of whorls

47, XXY

•Excess of arches

65
Q

Trisomy 21

A
  • Usually all are ulnar loops
  • With single palmar Creases in 50%.
66
Q

Connective Tissue Disorder

A

Positive Thumb Sign

67
Q

Sydney Line

A

Head line goes completely across palm

68
Q

Positive wrist sign

A

If hands are long they overlap

69
Q

Minor Anomalies of the FEET

A
  • Asymmetric length of toes
  • Clinodactyly of second toes with overlapping
  • Syndactyl
  • Short broad toenail
  • Deep crease between hallux and second toe

Wide gap between hallux and second toe

70
Q

Extremities

A
  • Abnormally positioned feet
  • Arachnodactyly
  • Extremely long and thin extremities
  • Loose joints
  • Single Palmar crease
  • Polydactyly
  • Short or tall stature
71
Q

Gynecomastia

A

Enlarged male breast

72
Q

Widespread nipples

A

Laterally displaced nipples

Turner** (also see cubitus valgus)

Shield chest

73
Q

Pectus Excavatum

A

A condition in which the breastbone sinks into the chest.

74
Q

Pectus Carinatum

A

deformity of the chest characterized by a protrusion of the sternum and ribs

75
Q

Umbilical Anomaly

A

Single umbilical artery – should have 2

Short umbilical cord

76
Q

Minor anomalies of Genitalia

A
  • Hypoplasia of the labia majora
  • Shawl scrotum
    • Condition in which the scrotum surrounds the penis
77
Q

Abdomen/Back Anomalies

A
  • Normal
  • Extra skin/prune belly
  • Umbilicus
  • Hepatomegaly
  • Splenomegaly
  • Diastasis recti
  • Umbilical Hernia
78
Q

Evaluate not only height BUT ALSO…

A

Upper body segment: lower body segment ratio

79
Q

Ash-leaf spot

A

white mark on skin

80
Q

Cafe au lait

A

brown skin macule

81
Q

Flammeus Nevis

A

flat red capillary skin stains

82
Q

Leopard’s Syndrome (7)

A

Lentigines (multiple)

Electrocardiographic conduction abnormalities

Ocular hypertelorism

Pulmonary stenosis

Abnormalities of genitalia

Retardation of growth

Deafness

83
Q

incontinentia pigmenti Whorl of pigment

A

Swirls on the skin,

swirls on the brain related to seizures and other health problems

Swirls follow lines of Blaschko

84
Q

Major Anomalies (Head - 5)

A

•CNS
Anencephaly/Meningomyelocele
Dandy - Walker malformation

•Agenesis of the corpus callosum

•Hydrocephalus, Microcephaly, Macrocephaly
Craniosynostosis

•Occiput/flat or prominent

•Delayed Closure of Fontanel
Anomalies

85
Q

Anencephaly

A

Absence of brain development

Absence of dermal covering

86
Q

Coloboma

A

Cleft of iris or lid

87
Q

Hypertelorism

A

Wide spaced eye

88
Q

Cherry red spot

A

Red area of macula of the retina

89
Q

Ectopia Lentis

A
  • Major criterion
  • Ectopia lentis
  • Minor criterion
  • Abnormal flat cornea
  • Increased axial length of globe
  • Hypoplastic iris causing decreased miosis
90
Q

Major eye finding

A

Coloboma of the Iris

91
Q

Feet – Major

A

Rocker bottom feet or curved foot

92
Q

Abdominal major defects

A

Abdominal wall defects

Kidney malformation

Anorectal defects

93
Q

Ambiguous Genitalia

A
  • Hypospadias and bifid scrotum
  • Micropenis
  • Vaginal atresia

Unusual Growth Patterns

94
Q

Neural Tube Defects

A

Neural tube is usually completed by 28th day of development: malformation can result in clubfoot, hydrocephalus, and spinal bifida depending on which part of neural tube is not closed.

95
Q

Cleft Lip and Palate

A

Failure of fusion of the frontal process with maxillary process at about 35th day of gestation

96
Q

BREAST CANCER, OBESITY, ALZHEIMER DISEASE, DIABETES ALCOHOLISM, HEART DISEASE:

A

Several inheritable traits are consider polygenetic