Embryo pt.5 Flashcards
Incidence of down syndrome
1 in 800
Incidence of trisomy 18
1 in 8000
Incidence of trisomy 13
1 in 12000
Usual clinical manifestations of down syndrome
- Mental deficiency
- brachycephaly
- Flat nasal bridge
- Flattened nose and face
- Protruding tongue
- Upward slant to palpebral fissures
- Transverse palmar flexion crease
- Clinodactyly of the fight finger (curvature of pinky fingure)
- Congenital heart defects
- GI tract abnormalities
What is brachycephaly?
- decrease in the anteroposterior dimension of the skull
- Lower than normal ratio of the skull’s length to its width
Usual clinical manifestations of Edwards syndrome
- Mental deficiency
- Growth retardation
- Ventricular septal defect
- Hypoplastic nails
- Short sternum
- Prominent occiput (back part of skull)
- Micrognathia (smaller lower jaw)
- Low set malformed eats
Usual clinical manifestations of patau syndrome
- Mental deficiency
- Severe CNS malformations
- Sloping forehead
- Malformed ears
- Sloping forehead
- Scalp defects
- Microphthalmia (Eyes are abnormally small and have anatomic malformations
- Polydactyly
- Bilateral cleft lip and/or palate
Incidence of triple x syndrome
1 in 1000
Incidence of 47 XXY
1 in 1000
Incidence of 47 XYY
1 in 1000
Triple X syndrome usual characteristics
- Normal in appearance
- Usually fertile
- 15-25% are mildly mentally deficient
Klinefelter syndrome characteristics
- Small testes
- Hyalinization of seminiferous tubules
- Aspermatogenesis
- Around 40% have gynecomastia
- Often tall with disproportionately long lower limbs
Contiguous syndrome most commonly affected chromosomes
Chromosome 15 q12 (Angelman and Prader Willi), Chromosome 17 (Williams and Miller Deiker, Smith Magenis), Chromosome 22q11 (DiGeorge, Velocardiofacial)
47 XYY usual characteristics
- Appear normal
- Usually tall
- Often exhibit aggressive behavior
Cause of DiGeorge
Del 22q11 (some cases)
Cause of Prader willi
Del 15q 12 (most cases) from paternal origin
Cause of Angelman
Del 15q 12 (most cases) from maternal origin
Cause of velocardiofacial
Del 22q11 (most cases)
Examples of contiguous gene syndromes
- Prader Willi
- Angelman
- Velocardiofacial
- Beckwith-Wiedemann
- Williams
- Smith-Magenis
- Di George
- Miller-Dieker
Cause of Miller-Dieker
Del 17 p13.3 (most cases)
Cause of Beckwith-Wiedemann
Dup 11 p15(some cases) from paternal
Cause of Williams
Del 17 q11.23 (most cases)
Cause of Smith Magenis
Del 17 p11.2
Clinical features of Prader-Willi
- Hypotonia
- Hypogonadism
- Extreme obesity with hyperphagia
- Distinct face
- Short stature
- Small hands and feet
- Mild developmental delay
- Learning disability
Clinical features of Angelman
- Microcephaly
- Macrosomia
- Ataxia
- Excessive laughter
- Seizure
- Severe mental deficiency
Clinical features of Miller Dieker
- Type 1 lissencephaly
- Dysmorphic face
- Seizures
- Severe developmental delay
- Cardiac defects
What is lissencephaly?
Literally means “smooth brain,” is a rare, gene-linked brain malformation characterized by the absence of normal convolutions (folds) in the cerebral cortex)
Clinical features of DiGeorge
- Thymic hypoplasia
- Parathyroid hypoplasia
- Conotruncal cardiac defects
- Facial dysmorphism
Clinical feature of velocardiofacial
- Palatal defects
- Hypoplastic alae nasi
- Long node
- Conotruncal cardiac defects
- Speech delay
- Learning disorder
- Schizophrenia like disorder
Clinical features of Smith-Magenis
- Brachycephaly
- Broad nasal bridge
- Prominent Jaw
- Shot and broad hands
- Speech delay
- Mental deficiency
Clinical features of Williams
- Short stature
- Hypercalcemia
- Cardiac defects, especially supravalvular aortic stenosis
- Characteristic elfin-like face
- Mental deficiency
Beckwith-Wiedemann clinical features
- Macrosomia
- Macroglossia
- Omphalocele (some cases)
- Hypoglycemia
- hemihypertrophy
- Transverse ear lobes
Macrosomia meaning
Larger than average fetus/baby
Macroglossia meaning
Tongue is larger than normal
