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NICU Board Review > Genetics > Flashcards

Genetics Flashcards

1
Q

What type of defect is cleft palate?

A

Déformation

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2
Q

What type of defect is potters sequence?

A

Primary defect malformation (renal issues)

Then deformation from oligohydramnios

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3
Q

Definition of major anomaly? Examples?

A

• MAJOR ANOMALY: a congenital anomaly severe enough to need
surgical intervention, increased morbidity and/or mortality,
potentially has a long-term impact medically and/or psychologically.
• Examples: cleft lip and palate, spina bifida / myelomeningocele, omphalocele,
duodenal atresia, congenital heart disease

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4
Q

Définition of Minor Anomaly ?

Examples?

A
  • MINOR ANOMALY: a congenital anomaly that requires no treatment at all or can be easily corrected, do not cause increased morbidity or mortality, often common in population.
  • Examples: postaxial polydactyly, abnormal palmar creases, low-set ears, preauricular tag
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5
Q

What complications can patients with 22q11 Deletion Sequence have?

A

• CHD (64%),
conotruncal, e.g., VSD, TOF, IAA type B, truncus, aberrant subclavian

• Palatal abnormalities (67%): velopharyngeal insufficiency, submucosal cleft, cleft palate, dysphagia

Airway/related: vascular ring, laryngeal web, subglottic stenosis

Gl: anteriorly placed/imperforate anus, esophageal atresia, umbilical / inguinal hernia

• Immune deficiency (77%) e.g., frequent infections, thymic hypoplasia

Craniofacial: prominent nasal bridge, micrognathia, asymmetric crying facies

• Hearing loss (sensorineural / conductive)

Developmental delay / learning difficulties (70%-90%)

Psychiatric: autism spectrum (20% of children), schizophrenia (25% of adults), ADD, anxiety

Skeletal: scoliosis, rib / vertebral anomalies, clubfoot

Genitourinary: hydronephrosis, renal anomalies, cryptorchidism, hypospadias

• Laboratory: hypoCa, hypoparathyroidism (50%), GH deficiency, cytopenias (lymphopenia)

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6
Q

Features of T18

A
  • Trisomy 18 aka Edward’s syndrome
  • Majority (95%) of trisomy 18 conceptuses spontaneously aborted
  • Incidence 1/7500 livebirths

Clinical features:
• Physical: prominent occiput, low set ears, micrognathia, small mouth, high arched palate, clenched fists (2nd and 5th fingers overlapping 3rd and 4th), rockerbottom feet, hypoplastic nails (especially 5th fingernail), short sternum, hypertonia

• Other / major anomalies: CHD (VSD, PDA, ASD, poly-valvular disease) in 80-100%,
central apnea - respiratory failure, horseshoe kidneys

  • Postnatal survival poor: 50% die in 1st week, most do not live past 1st year
  • Severe intellectual disability in survivors
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7
Q

Describe Potters sequence

A

• Potter sequence (deformation)

• External and internal abnormalities caused by
oligohydramnios

• Primary defect a malformation: posterior urethral valves, renal
agenesis, multicystic dysplastic kidneys

• Lack of fetal urine > oligohydramnios > fetus has a flat face due to compression of the face against the uterine wall, club foot due to no room for significant movement, and associated lung hypoplasia

• “Potter facies”: wrinkly skin, low-set ears, flat nose & chin, widely
spaced, epicanthal folds.

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8
Q

T21 is most at risk for

A. Intestinal atresia
B. Congenital hypothyroidism
C. Transient myeloproliferative disorder (TMD)
D. Hirschsprung’s disease

A

A. Intestinal atresia (Duodenal atresia)

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9
Q

Features of 22q11 deletion syndrome

A

• CHD (64%), especially conotruncal, e.g., VSD, TOF, IAA type B, truncus, aberrant subclavian

Palatal abnormalities (67%): velopharyngeal insufficiency, submucosal cleft, cleft palate, dysphagia

Airway/related: vascular ring, laryngeal web, subglottic stenosis
Gl: anteriorly placed/imperforate anus, esophageal atresia, umbilical / inguinal hernia

• Immune deficiency (77%) e.g., frequent infections, thymic hypoplasia

Craniofacial: prominent nasal bridge, micrognathia, asymmetric crying facies

Hearing loss (sensorineural / conductive)

Developmental delay / learning difficulties (70%-90%)

Psychiatric: autism spectrum (20% of children), schizophrenia (25% of adults), ADD, anxiety

• Skeletal: scoliosis, rib / vertebral anomalies, clubfoot

Genitourinary: hydronephrosis, renal anomalies, cryptorchidism, hypospadias

Laboratory: hypoCa, hypoparathyroidism (50%),
GH deficiency, cytopenias (lymphopenia)

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10
Q

Feature of Noonan

A

• Autosomal dominant

Multiple genes: most common PTPN11 in 50%, other genes include SOS1, RAF1, RIT1,
KRAS

  • CHD: most common pulmonary valve stenosis (PS), hypertrophic cardiomyopathy
  • Broad/ webbed neck

Characteristic faces
• Low-set posteriorly rotated ears, blue-green irises, widely-spaced downslanting eyes, ptosis.

Chest wall abnormalities: superior pectus carinatum, inferior pectus excavatum

Widely spaced nipples
• Short stature
• Cryptorchidism

Developmental delay (variable degree)

Coagulation defects, e.g., PT, PTT, platelet count may show abnormalities.

• Lymphatic dysplasias of the lungs, intestines, and/or lower extremities

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11
Q

How do you confirm T21

A

Routine Karyotype

Robertsoniam translocation - can increase risk for future pregnancies up to 15%

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12
Q

When to order microarray ?

A

It is the first-line test recommended by the American

College of Medical Genetics (ACMG) for multiple congenital anomalies that do not fit a specific pattern of diagnosis

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13
Q

How to test for CF?

A

Single gene sequencing: CFTR gene for cystic fibrosis.

**The majority of infants with meconium ileus end up having cystic fibrosis. 20% of
CF patients present in the neonatal period with meconium ileus.

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14
Q

How to test for BWS

A

• DNA Methylation studies

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome
that should be suspected if a neonate has one or more of the
following major/minor findings.
• Major findings: macrosomia, macroglossia, hemihyperplasia,
omphalocele, embryonal tumor (e.g., Wilms tumor, hepatoblastoma),
visceromegaly, anterior linear ear lobe creases and/or posterior
helical ear pits, large placenta
• Minor findings (relatively common in population): polyhydramnios,
prematurity, neonatal hypoglycemia, vascular lesions e.g. nevus
simplex (forehead, back of the neck)

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15
Q

Most common gene imprinting error during in vitro fertilization

A

Beckwidth wiedemann syndrome

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16
Q

What does dysostosis refer to?

A

Abnormalities in early patterning events during skeletal development

Occurs GA 3-6 weeks

Ie: spondylocostal dysostosis (AR, mutation in notch ligand DLL3)

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17
Q

What is the genetic defect associated with trnasient neonatal diabetes mellitus? Chromosome?

A

Genomic imprinting
Chromosome 6

Manifests with IUGR, FTT, hyperglycemia and dehydration 4-6 weeks

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18
Q

3 year old girl with developmental delay, hand foot sucking and cheerful disposition. Dx and chromosomal location?

A

Angelman syndrome

Deletion of maternal inherited gene UBE3A on Chromosome 15q11

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19
Q

What diagnostic test do you send to diagnose uniparental disomy?

A

Single nucleotide polymorphism microarray

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20
Q

Comparative genomic hybridization refers to which test?

A

Fancy way of saying Microarray

Can detect deletions or duplications

Takes longer than karyotype

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21
Q

Beckwidth wiedemann is associated with (gain or deletion)?

A

Gain of methylation of maternal chromosome or paternal duplication

Overgrowth, think double

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22
Q

Supravalvular subaortic stenosis is associate with which syndrome?

A

Williams

7q11 deletion

Can also have peripheral pulmonic stenosis, hypoplastic nails, prominent lips, hoarse voice, stellate iris pattern, mental deficiency

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23
Q

Cell free fetal DNA is usually _______ than are maternally derived cfDNA

A

Shorter

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24
Q

Most commin presenting clinical manifestation klinefelter syndrome?

A

Infertility from azoospermia

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25
Q

Iugr, microcephaly, short sternum, camptylodactlyly, clenched hand, multicystic dysplastic kidney. Dx?

A

Trisomy 18

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26
Q

Triangular face, IUGR, 5th finger clinodactyly, leg length asymmetric, cryptoorchidism. Dx?

A

Silver Russell Syndrome

Remember this is a genomic imprinting disorder

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27
Q

Large polycystic kidneys, post axial polydactyly, occipital encephalocele. Dx?

A

Meckel Gruber syndrome (AR)

Chromostome 17

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28
Q

How is mRNA formed?

A

From transcription of DNA

Primary mRNA is formed first, undergoes splicing (removal of introns) to form mature mRNA

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29
Q

Ribosomal RNA

A

RNA that is part of ribosome and helps bind mRNa and tRNA to ribosome

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30
Q

Transfer RNA

A

RNA that transports amino acids and assists in translation of mature mRNA

The anticodon portion of tRNA (contains specific AA at 3’ end) binds to complementary mRNA codon

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31
Q

Transcription

A

MRNA is synthesized from DNA template

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32
Q

DNA polymerase

A

Enzyme important in DNA replication by utilizing complementary DNA strands as a template to synthesize new strand

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33
Q

RNA polymerase

A

Enzyme that binds to promoter region and synthesizes mRNA from a DNA template

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34
Q

Reverse transcriptase

A

Enzyme that transcribes RNA into DNA (reverses transcription)

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35
Q

Intron

A

Dna sequence of a gene located between 2 exons that is transcribed into mRNA but spliced out during formation of mature mRNA

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36
Q

Exon

A

DNA sequence of gene located between 2 introns that is transcribed into mRNA and retained after primary mRNA is spliced

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37
Q

Contains introns and exons

A

Genome

38
Q

Exome

A

Coding region of genome (~1.5% of genome)

39
Q

Promoter

A

DNA sequence located 5’ to a specific gene

RNA polymerase binds to this region so that transcription (DNA to mRNA) can occur

40
Q

Enhancer

A

Dna sequence that interacts with specific transcription factors and leads to increased transcription of gene

41
Q

Polyadenylation sequence

A

Important for mRNA stabilization

100-200 adenibe nucleotides locared at the 3’ end of primary mRNA

42
Q

Translation

A

Process by which an aminoacid sequence is assembled utilizing mature mRNA

tRNA is required for translation

43
Q

Difference of southern, northern and western analysis

A

Southern analysis-DNA is digested and exposed to DNA probe

Northern analysis-labeled DNA probe to digested RNA

Western analysis- used to identify protein of interest

44
Q

How many newborns have a minor malformation?

A

13% have 1 minor

  1. 8% 2 minor
  2. 5% 3 minor

2-3% major malformation

Remember malformation is abnormal tissue formation (CHD, cleft palate, micrognathia, renal agenesis)

45
Q

Arthrogryposis is what type of abnormal morphogenesis?

A

Deformation

Associated with altered mechanical forces on normal tissue

46
Q

What type of abnormal morphogenesis is amniotic band?

A

Disruption

Breakdown of normal tissue

47
Q

What type of abnormal morphigenesis is a hemangioma?

A

Dysplasia

Abnormal organization of cellular formation into tissue.

Ectodermal dysplasia is another example

48
Q

What type of Abnormal morphogenesis is pierre robin?

A

Sequence

Primary mandibular development with secondary findings of micrognathia, cleft palate and glossoptosis

49
Q

Match the mutation with disease (point mutation, frameshift, splice cite ir triple repeat mutation)

CF
Thalassemia
Fragile X
Sickle cell
Myotonic dystrophy
A

CF- nonsense point mutation (stop codon, shorter protein)
Thalassemia-splice site muration (intron isnt removed)
Fragile X-trinucleotide repeat CGG>50
Sickle cell-missense point mutation glutamic acid to valine at Ch 6
Myotonic dystrophy CTG> 100 severe

50
Q

Most common single gene disorder in the Caucasian population

A

Cystic fibrosis

51
Q

Diseases associated with advanced paternal age

A 
Achondroplasia
Apert syndrome
Crouzon syndrome
Neurofibromatosis
Osteogenesis imperfecta
Thanatophoric dysplasia
Klinefelter syndrome and Trisomy 21-possible slightly increased risk
52
Q

Genetic disorders associated with advanced maternal age

A

Klinefelter syndrome
Trisomy 13
Trisomy 18
Trisomy 21

53
Q

What does massive parallel shotgun sequencing detect (MPPS)?

A

Highly sensitive in the detection of fetal aneuploidy (including Turner’s)

This is one of the types of NIPT

54
Q

How does newborn screen detect disease?

A

Mass spectrometry

55
Q

Analysis of allele ratios in cfDNA is useful to detect

A

Aneuplodies

56
Q

Most commonly used biomarker for oxidative stress

A

Ratio of reduced to oxidized glutathione

57
Q

DNA methylation of cytosine of a Cpg dinucleotide is an example of which type of gene regulation?

A

Epigenetic modification

58
Q

Clenched fists, scalp defect, holoprosencephaly, cleft lip and palate. Dx?

A

T13

59
Q

What is a major diagnostic criterion with the highest frequency in CHARGE syndrome

A 
Major:
Coloboma (80-90%)
Cranial nerve dysfunction (75-95%)
Choanal atresia/stenosis (50-60%)
Ear anomalies (90%)

Minor:
Genital hypoplasia
Cardiac
Developmental delay

60
Q

What are the 3 epigenetic modifications?

A

Dna methylation
Histone modification
Imprinting and x inactivation

61
Q

Name some multifactorial disorders

A 
Cleft lip palate
Anencephaly
Spina bifida
Clubfoot
Congential hip dysplasia
Pyloric stenosis

Usually w unaffected parents. Greates risk with increasing #affected family members, closeless or relatedness

62
Q 
Whats the recurrence risk for
Cardiac defect
Cleft lip
Cleft palate 
Club foot
Developmental hip dysplasia 
Hirschprungs
NTD 
Pyloric stenosis
T21
A 
Cardiac defect 
Cleft lip
Cleft palate 
Club foot
Developmental hip dysplasia 
Hirschprungs
NTD

All between 3-5% if one affected prior child

If parent affected 10% Risk for CHD and cleft lip and 25% for club foot.

Pyloric stenosis 3% risk sibling, mother 19% risk if boy 7% girl, dad affected 5.5% if boy and 2.4% if girl

T21- 1% sibling, mom w balanced translocation 10–15% and dad w balanced translocation 5%

63
Q

Broad thrumbs and 1st toes, beaked nose . Dx?

A

Rubenstein Taybi Syndrome

Also have microcephaly, cryptorchidism, postnatal growth deficiency

64
Q

Name the syndrome associated with supravalvular aortic stenosis

A

Williams syndrome

7q11 deletion of an elastin gene

After supravalvular aortic stenosis next most common is peripheral pulmonic stenosis

65
Q

Trident hands, megalocephaly with small foramen magnum, short limbs. Dx? And gene affected?

A

Achondroplasia, AD

Fibroblast growth factor receptor 3 gene

66
Q

Midface hypoplasia, craniosynostosis, broad distal phalanx of thumb/bigtoe. Dx?

Maxillary hypoplasia, premature craniosynostosis, less risk of mental deficiency. Dx?

A

Apert syndrome=acrocephalosyndactyly

Crouzon=Craniofacial dyostosis

Both mutations in fibroblast growth factor 2 gene

67
Q

Absent hypoplastic or abnormally shaped thumbs, ASD and narrow shoulders. Dx?

A

Holt oram syndrome

68
Q

Flat facies, mid facial/mandibular hypoplasia and spondyloeouphyseal dysplasia. Dx?

A

Stickler syndrome

69
Q

Clover leaf skull, large cranium to body size, bowed humerii, short limbs, narrow thorax. Dx?

A

Thanatophoric dysplasia

Mutation in fibroblast growth factor receptor 3

70
Q

White forelock, partial albinism, deafness. Dx? Associated instestinal anomaly?

A

Waardenburg

Hirshprungs

71
Q

Most common mechanism of altered imprinting in beckwith wiedeman syndrome

A

Loss of methylation of imprinting control region 2 on the maternal chromosome

72
Q

Deletion of elastin gene, broad forehead, periorbital fullness, long philtrum, wide mouth. Dx and associsted cardiac anomaly

A

Williams syndrome

Supravalvular aortic stenosis

Also has hypercalcemia

73
Q

Oligohydramnios, FGr, hydrops, multiple congenital anomalies (including renal). Which disorder?

A

Triploidy

69XXX

74
Q

What marker will help differentiate hypophosphatasia from other lethal skeletal dysplasias. What is treatment?

A

Alkaline phosphatase

Enzyme replacement: asfotase alfa

75
Q

Cleft palate
Polydactyl
Ambiguous genitalia
Deficiency of 7 dehydro cholesterol

A

Smith Lemli opitz

AR

76
Q

MCC of adrenal insufficiency in the newborn

A

CYP21 gene mutation

CAH

77
Q

Syndactyly especially of the 3rd and 4th fingers is a characteristic feature of which genetic abnormality?

A

Triploidy

Think of this if cffDNA is reported as non-informative or negative with other anomalies similar to T18/13

If cffDNa is performed it might be reported as non-informatice because there is an insufficient fetal fraction of cfDNA (esp w very small placentas)

78
Q

Condition associated eith DHCR7 gene

A

Smith Lemli Opitz

79
Q

Condition associated transcription factor TBX5?

A

Holt Oram

80
Q

Preterm renal characteristics vs term

A

Lower GFR
Lower urine osmolarity (term 800 mOsm/L vs 500 in preterm)
Lower abilitt to reabsorn Na+ H20
Decreased ability acidify urine

81
Q

Small / narrowing of the foramen magnum is associated with _____.

A

Achondroplasia

AD
Fibroblast growth factor receptor 3 gene
Trident hands

82
Q

Transmission from females
All offspring of affected females will be affected
Male offspring does not pass disease

A

Mitochondrial

83
Q

Mom transmits to boys and daufhters
Boys are affected
Girls are cariers

A

X linked recessive

84
Q

More common in females (2x more common than in males)
Father passes to girls
Father cannot pass to sons
Both parents can pass it on

A

X linked Dominant

85
Q

Incidence of major malformation?

Incidence of minor malformation?

A

2-3% of newborns with major malformation

13% of newborns with 1 minor malformation

  1. 8% with 2 minor malformation
  2. 5% with 3 minor malformation
86
Q

What is assoc’d with fibroblast growth factor 3?

What is assoc’d with fibroblast growth factor 2?

A

FGF3 - thanatrophic. Achondroplasia

FGF2 - Apert, Crouzon, Pfeiffer

87
Q

Neonates hypotonia cardiomegaly and macroglossia. What is elevated un these neonates?

A

Pompes diseases (alpha glucosidase deficiency)

Very high CPK

88
Q

Mitchell-Riley syndrome (MRS)

A

autosomal recessive disorder characterized by neonatal diabetes with congenital gastrointestinal and hepatobiliary anomalies. It is caused by mutations of the RFX6 gene, which is located on chromosome 6q22 adjacent to genes implicated in transient neonatal diabetes mellitus. RFX6 encodes regulatory factor X6, a member of the RFX family of transcription factors that is expressed in the proximal intestine, pancreas, and liver. Manifestations associated with MRS include intrauterine growth restriction, duodenal atresia, neonatal diabetes, pancreatic insufficiency, anemia, hepatic siderosis, and biliary atresias.

89
Q

Most common mechanism for prader Willi and angelman syndromes

A

Micro deletion 70% of the paternally inherited chromosome 15 (prader willi ) and maternal for angelman

Uniparental disomy 20%

Imprinting error <5%

90
Q

Skeletal Dysplasia vs

Skeletal dystoses

A

Dysplasia = abnormal organization

Dysostoses = bone malformation

NICU Board Review (19 decks)

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