Genetic syndrome visual diagnosis Flashcards
Down Syndrome
- Aneuploidy T21
- Cause: maternal nondisjunction (>90%) and robertsonian translocation (5%)
- Facial features:
- Upslanting palpebral fissues
- Epicanthal folds
- Redundant neck folds
- Midface hypoplasia
- Flat occiput (brachycephaly)
- Delayed dentition
- Protruding tongue
Single palmar crease
Seen with:
- Down syndrome
- Cri-du-chat
- Trisomy 13
- Smith-Lemli Opitz
Noonan syndrome (RASopathy - due to changes in cell signaling pathway)
- Downslanting palpebral fissures
- Epicanthal folds
- Webbed neck
- Hypertelorism
- Low-set ears
- Low posterior hair line
- Shield chest +/- pectus
Other associations: pulmonic stenosis (CCHD!), short stature, bleeding daithesis, scoliosis
Etiology: usually sporadic, multiple genes identified, some cases are AD
Cri-du-Chat Syndrome
Etiology: 5p deletion
Features:
- microcephaly
- high-pitched cry (mewing cat)
- hypertelorism
- low-set ears
- small jaw
*
Neurofibromatosis Type 1
Etiology: mutation in the NF1 gene
Features:
- cafe-au-lait spots
- axillary freckling
- Lisch nodules in the iris
- short stature
- macrocephaly
Diagnostic criteria NF-1
2 of the following:
- Cafe-au-lait spots
- More than 6
- >5mm if prepubertal
- >15mm if post-pubertal
- More than 6
- Two or more neurofibromas
- Optic glioma
- Axillary or inguinal freckling
- Two or more Lisch nodules
- Osseous lesion (tibial pseudoarthrosis, sphenoid dysplasia)
- 1st degree relative with NF-1
Cri-du-chat
5p deletion
DiGeorge Syndrome/ 22q11.2
Etiology: microdeletion on chromosome 22q
Facial features:
- hooded eyelids
- bulbous nose
- small ears
- small mouth and chin
- flat nasal bridge
Other associations:
- cleft palate
- feeding difficulties
- hypernasal speech
- can present with asymmetric crying facies
- immunodeficiency (hypoplastic thymus)
- thyroid disease
- CHD present 85% - VSD most common
- hypocalcemia
- thrombocytopenia
- developmental delay
- mental illness later in life
*Aka velocardiofacial syndrome, CATCH22, conotruncal anomaly facial syndrome*
Turner syndrome
Etiology: single x chromosome, generally sporadic
Features:
- Short stature*
- Ovarian failure
- Webbed neck with low posterior hairline
- Cubitus valgus
- Mild intellectual impairment (social, visuo-spatial)
- Congenital lymphedema
- Broad chest with wide-set nipples, +/- pectus
- Abnormally shaped ears (80%)
- Horseshoe kidney
- Cardiac - bicuspid aortic valve (30%), coarct (10%)
*
Edward syndrome (Trisomy 18)
Features:
- Overlying index finger
- fingernail hypoplasia
- rocker bottom feet
- polydactyly
Beckwith-Weidemann syndrome
Etiology: abnormal gene balance chromosome 11, 10-15% transmitted AD, otherwise sporadic
Features:
- Exomphalos (omphalocele, umbilical hernia)
- Macroglossia (difficulties with speech, feeding)
- Gigantism (tapers off by age 8)
- Hypoglycemia (30%)
- Capillary nevus flammeus
- Normal development
- Linear fissures lobule of ears
At increased risk of:
- Wilms tumour
- Hepatoblastoma
*Overgrowth syndrome*
Patau syndrome (T13)
Etiology: T13, associated with advanced maternal age
Features:
- CNS: holoprosencephaly
- Microcephaly with large fontanelles
- Midline facial defects:
- Cleft lip and/or palate (60-80%)
- Single eye or micropthalmia/anopthalmia
- CHD (80%) - VSD, ASD, PDA
- Hypospadias and cryptorchidism
- Polydactyly
- Clubfeet or rocker-bottom feet
- Cutis aplasia
Prader-Willi syndrome
Achondroplasia
Turner syndrome
- lymphedema
- deep-set nails
- raised fingertip pulp
- short metatarsals
Edward syndrome (T18)
Etiology: T18, 2nd most common multiple-malformation syndrome
Features:
- Facial: low-set malformed ears, micrognathia, small oral opening, prominent occiput, mild hirsutism
- Extremities: overlapping digits, polydactyly, nail hypoplasia
- Abdomen: inguinal and umbilical hernias
- Cardiac: VSD, ASD, PDA
