1 Peds Genetics Flashcards

1
Q

What’s the real name for “brittle bone disease”?

A

Osteogenesis Imperfecta

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2
Q

What type of genetic disease is OI?

A

Autosomal dominant mostly

Some autosomal recessive subtypes

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3
Q

Majority of cases of OI involve mutations in what genes?

A

Alpha-1 and alpha-2 chains of TYPE I COLLAGEN (COLA1 or COLA2)

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4
Q

Which subtype of OI is the most common?

A

Type I

It’s mild. Sometimes you wouldn’t even know by looking at them that they’s got fucked up bones.

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5
Q

Which subtype of OI is the most severe?

A

Type II

Usually lethal in utero

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6
Q

How many other subtypes of OI are there?

A

Types III-IX: Moderate-severe with characteristics of everything in between

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7
Q

Key clinical features of osteogenesis imperfecta

A
Excessive/atypical fractures***
Short stature
Bowlegs or other limb deformities
Scoliosis/kyphosis*** (more common with Type III-IX, can lead to breathing difficulties)
Basilar skull deformities —> spinal cord concerns
BLUE SCLERAE******************
Hearing loss (progressive)***
Opalescent teeth***
Ligament and skin laxity
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8
Q

What are the dental findings in OI called?

A

Dentinogenesis imperfecta

Opalescent teeth

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9
Q

What is a common imaging modality for early diagnosis of OI?

A

Maternal U/S if severe

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10
Q

Fractures at various stages of healing that may be misdiagnosed as child abuse

A

Osteogenesis imperfecta

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11
Q

What are some hallmark imagining findings suggestive of OI?

A

Wormian bones (suture bones of skull)

Codfish vertebrae (vertebral bodies bi-concave from compression fractures)

Osteopenia

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12
Q

Why might you skip f/u xrays for a simple fracture in a kid with OI?

A

To minimize radiation exposure

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13
Q

How is OI usually diagnosed?

A

Often it’s a clinical diagnosis, especially if family history (unless you want to determine the specific subtype)

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14
Q

What does biochemical testing do for us in OI?

A

Helps evaluate structure and quality of type I collagen

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15
Q

Common lab findings in OI

A

Vitamin D, phosphorus, alkaline phosphates may be normal or elevated with recent fracture

HYPERCALCEMIA is common and relates to severity (b/c bones constantly being remodeled)

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16
Q

What is the main medicinal treatment for OI?

A

Bisphosphonates - Pamidronate (IV infusion every 3 months: 4 hours daily for 3 days)

Slows down bone reabsorption —> reduces fracture rates and increases bone density

Risks of hypocalcemia, OSTEONECROSIS OF THE JAW, and nephrotoxicity. But it’s helpful, I guess.

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17
Q

Marfan syndrome is a genetic mutation in …

A

Connective tissue protein FBN1 (fibrillin)

Autosomal dominant

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18
Q

Cardiac effects of Marfan syndrome

A

AORTIC ROOT DILATION/DISSECTION**
—> Aortic rupture risk

Mitral valve prolapse

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19
Q

What pulmonary condition are Marfan patients more predisposed to experience?

A

Spontaneous pneumothorax

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20
Q

What are the ophthalmologic effects of Marfan syndrome?

A

Myopia (nearsightedness)

Lens subluxation/dislocation

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21
Q

Musculoskeletal presentation of Marfan syndrome

A

Tall, thin with increased arm span/ht ratio

SCOLIOSIS

ARACHNODACTYLY (look for positive hand signs)

Pectus deformity

Hind foot valgus

Hyper mobile joints with laxity

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22
Q

Steinberg sign

A

Used for clinical evaluation of Marfan patients

Fold your thumb into the closed fist. Test is positive if the thumb tip extends from the palm of the hand.

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23
Q

Walker-Murdoch sign

A

Used for clinical evaluation of Marfan patients

Grip your wrist with your opposite hand. If thumb and fifth finger of the hand overlap with each other, this represents a positive test.

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24
Q

How is marfan diagnosed?

A

CVS or amniocentesis may detect defective gene

DNA testing

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25
Q

How do you evaluate a patient with Marfan?

A

ECHO/ECG to look for cardiac issues

Eye exam including slit lamp for lens dislocation

Radiographs: CXR, skeletal abnormalities

MRI/CT PRN

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26
Q

How do you manage patients with Marfan?

A

Involve specialists - Cardio, Ortho, Ophtho

Meds: Beta blocker (to take stress off the heart)

Strenuous activity restrictions

Possible surgery, if enlarged aorta, progressive scoliosis, chest deformity, eye problems

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27
Q

Where is the genetic defect in Prader-Willi Syndrome?

A

Affects long arm of Chromosome 15 - due to absence of PATERNAL gene expression

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28
Q

What is the primary cause of dysfunction in Prader-Willi Syndrome?

A

Hypothalamic or pituitary dysfunction —> primary central growth hormone deficiency

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29
Q

Expression of a gene depends on gender of parent donating the gene

A

Genetic imprinting

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30
Q

Uniparental disomy of Chromosome 15 leads to ______ if lose is paternal and _____ if loss if maternal

A
Paternal = Prader-Willi syndrome***
Maternal = Angelman syndrome
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31
Q

Which is more common - Prader-Willi or Angelman?

A

Prader-Willi - 75% of cases of chromosome 15 disomy

Angelman —> less distinct features, higher IQ, milder behavioral problems

PWS —> more likely to have autistic behaviors

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32
Q

Physical traits of PWS

A
Almond shaped eyes
Triangular mouth
Narrow forehead
Short stature
Small hands and feet
Depigmentation (skin and eyes)
Hypogonadism (typically sterile)
Risk for osteoporosis
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33
Q

Social concerns for PWS

A

Developmental delay

Intellectual disability

Behavioral problems

Food seeking behavior

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34
Q

PWS in infants vs early childhood

A

Infants: profound HYPOTONIA —> feeding difficulties and FTT

Early childhood: HYPERPHAGIA and weight gain (binge eating)

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35
Q

Diagnosis of PWS is via…

A

Molecular genetic test —> Methylation analysis

36
Q

Management of PWS

A

Limited 😔

Replace HGH and testosterone/estrogen
Healthy diet/exercise
Multidisciplinary therapies
May consider group home
Monitor for complications

Meds for hyperphagia generally not helpful

37
Q

PWS complications

A
Type 2 DM
Heart disease/stroke
Sleep apnea
Joint “wear and tear”
Psychological component
38
Q

Most common inherited intellectual disability

A

Fragile X

X-linked recessive disorder

39
Q

Because Fragile X is X-linked, it has…

A

Higher incidence/severity in males

40
Q

What is the Lyon hypothesis?

A

Because they have two X’s, variable expression due to X-activation (mosaicism) means they are typically ok in diseases like Fragile X

41
Q

______% of x-linked recessive disorders are new mutations

A

90%

42
Q

What clinical presentation is usually the reason boys end up being diagnosed with Fragile X?

A

Intellectual impairment —> genetic testing

43
Q

Clinical presentation of Fragile X

A
Intellectual impairment
Developmental delay (late language and motor delay)
Autistic behaviors
Poor ability to cope with transitions
Hyperactivity
Anxiety
Behavior/tantrums
Seizures
44
Q

Physical characteristics of kids with Fragile X

A

Soft smooth skin

Microcephalic with prominent forehead/chin

Large ears and long, narrow face

MSK: joint laxity, hypotonia, pes Plano’s

Eye: Strabismus, blue iris

CV: Mitral valve prolapse (murmur)

Macro-orchid is after puberty

45
Q

What is the specific gene that causes Fragile X?

A

CGG repeat in FMR1 gene (FragileX Mental Retardation Gene)

Pre-mutations (present slightly differently):
• Primary ovarian insufficiency (FXPOI)
• Tremor/ataxia syndrome (FXTAS)

46
Q

How do you manage patients with Fragile X?

A

Multidisciplinary: med consults, various therapies, patient/parent ed

Echo

MRI and eval if seizures

GERD: meds, feeding therapy

PT, OT, Speech, individualized educ plan

47
Q

What gene is affected in DiGeorge Syndrome?

A

22q11.2 defection

48
Q

What is the inheritance pattern for DiGeorge Syndrome?

A

Autosomal dominant, but most often occurs randomly

49
Q

Classic triad of SSx for DiGeorge Syndrome

A

Cardiac abnormalities
Hypoplastic thymus
Hypocalcemia

50
Q

Subtypes of DiGeorge Syndrome is based upon …

A

Thymic hypoplasia and immune function

Can be partial or complete

51
Q

How do cardiac symptoms present in DiGeorge Syndrome?

A

Can be asymptomatic with mild defects

More severe present with potential cyanosis, HF, FTT, and/or respiratory distress

52
Q

Complete DiGeorge Syndrome is characterized by…

A

Complete absence of the thymus —> immunodeficiency

53
Q

Why to DiGeorge patients end up with hypocalcemia?

A

Due to underdeveloped parathyroid

54
Q

Besides the classic triad of SSx, what other potential concerns do DiGeorge patients have?

A

Craniofacial abnormalities (low set ears, wide set eyes, underdeveloped chin/small mouth, bulbous nose tip)

Palatial defects —> speech delay/difficulty

GU abnormalities

Recurrent infections/inflammatory diseases (b/c thymus hypoplasia)

Can also have skeletal concerns, developmental delay, and behavioral issues)

55
Q

Dx of DiGeorge is based on…

A

Decreased CD3+ T cells and clinical findings

There are three different criteria for Dx (“Definitive”, “Probable”, “Possible”)

56
Q

Initial evaluation of DiGeorge Syndrome should include…

A

Urgent echo (b/c of cardiac concerns)

Labs: CBC w/ diff, Ca and PO4

Renal U/S

CXR —> thymic shadow

57
Q

How do you manage DiGeorge Syndrome?

A

Cardiac consult (observation v surgery)

Genetic consult for screening/counseling

Endocrine consult

Speech/feeding therapist

Behavioral/psychiatric counseling in adolescents

CAUTION with live vaccines

Isolation???

58
Q

What is the prognosis for Complete DiGeorge?

A

Life expectancy in infant is less than 1 year without treatment

Thymic transplant if possible (if they do, they usually do quite well)

Hematopoietic stem cell transplant

59
Q

Chromosomes with any number other than 46

A

Aneuploidies

Examples:
Klinefelter Syndrome
Turner Syndrome
Trisomy 13, 18, and 21

60
Q

47, XXY

A

Klinefelter Syndrome

61
Q

When does Klinefelter typically present?

A

POSTPUBERTAL

Infants and pre-pubertal boys typically have no obvious signs

Tall stature, narrow shoulders, long legs, microorchidism, gynecomastia, mild language delay/learning disabilities

62
Q

What do labs look like in Klinefelter syndrome?

A

Testosterone low, FSH/LH elevated in adolescents (consider testosterone replacement)

Infertility eval: 50% may be able to father kids with assistance

63
Q

45, XO

A

Turner Syndrome

1 in 2000 females

Can be result of mosaicism:
45,X / 46, XX
45,X / 46, XY with partial or complete deletion of Y

64
Q

Turner patients have higher risk for …

A

X-linked recessive disorders such as hemophilia A/B

65
Q

Short stature, low hairline, webbed neck, broad chest with wide spaced nipples, shield chest, pigmented nevi, average intellect

A

Turner Syndrome

Infants: lympedema in dorsum of hands and feet, CHD

66
Q

Common cardiac findings in Turner Syndrome

A

COARCTATION OF THE AORTA (risk for aortic dissection)

Bicuspid AV (aortic stenosis)

HTN

67
Q

MSK findings in Turner Syndrome

A

Cubits Valgus

Short 4th metacarpals

Madelung Deformity

68
Q

GU findings in Turner Syndrome

A

STREAKED GONADS (underdeveloped)

Premature ovarian failure

Primary amenorrhea (small % can still get preggo)

HORSESHOE KIDNEY (or other renal malformations)

69
Q

Management of Turner Syndrome

A

Multidisciplinary team

Infertility —> IVF with egg donation (pregnancy risky b/c of risk of aortic dissection)

Estrogen and cyclic progesterone therapy to stimulate puberty and assist with bone density

Monitor for gonadal malignancy (maybe prophylactic removal of gonads)

Counseling

70
Q

What are the three trisomies that are possible?

A

Trisomy 13 = Patau Syndrome

Trisomy 18 = Edwards Syndrome

Trisomy 21 = Down Syndrome

71
Q

Majority of which trisom(ies) die en utero?

A

Trisomy 13 and 18

72
Q

Which trisomy results in midline craniofacial, eyes, forebrain?

A

Trisomy 13 (Patau)

Defect is prechordal mesoderm

73
Q

Clinical features of Trisomy 13

A

Midline cleft lip and palate, sloping forehead, scalp defects, micro-ophthalmia, holoprosencephaly

MSK: HYPOtonia, clinodactyly, polydactyl, vertical talus

Severe intellectual disability, kidney defects, CHD, omphalocele

74
Q

Prognosis for Trisomy 13

A

The worst

Majority die in utero

Affected infants usually die before 1 month of age and <5% survive beyond 6 months

Currently supportive care is recommended (“noninterventional paradigm”)

75
Q

Clinical features of Trisomy 18 (Edwards)

A

Intrauterine growth restriction with low birth weight, low set ears, microcephalic, small jaw/mouth, prominent occipital

MSK: HYPERtonia/spasticity, overlapping digits, rocker bottom foot, short sternum

Horseshoe kidney

Airway obstruction

Omphalocele

CHD (VSD and PDA)

76
Q

Prognosis for Trisomy 18

A

Majority die in utero

50% die within 2 weeks and only 5 % survive beyond 1 year

77
Q

Most common chromosomal abnormality (1/600)

A

Trisomy 21 (Down)

78
Q

Typical developmental delay in Down Syndrome is …

A

Twice the average age

79
Q

Risk of Down Syndrome is increased with…

A

Advanced Maternal age

25 yo: 1/1350
35 yo: 1/350
45 yo: 1/35

80
Q

Clinical features of Trisomy 21

A

Epicanthic folds, flat nasal bridge, folded low set ears, brachycephaly, brushfield spots (speckled iris), open mouth, protruding furrowed tongue, short neck with excessive skin, narrow palate, upslanting palpebral fissures

81
Q

50% of Down Syndrome patients have…

A

CHD

Ex: AVSD, VSD, ASD, PDA, TOF

82
Q

HEENT findings in Down Syndrome

A

Visual (cataracts, refractive errors)

Hearing (conductive loss with multiple infections)

Abnormal teeth

83
Q

Pulmonary findings in Down Syndrome

A

Pulmonary HTN

Intermittent hypoxia

Obstructive sleep apnea

Recurrent PNA

84
Q

GI findings in Down Syndrome

A

Duodenal atresia

Chronic constipation

Hirschprung Disease

Celiac

85
Q

MSK findings in Down Syndrome

A

Short stature, HYPOtonia, joint laxity, short hands, transverse palmar crease (Simian line), space between 1st and 2nd toes