Genetic disorders

Question 1

Phenotype vs genotype

Answer 1

Phenotypic presentation specific to genetic disorder, may include:
- dysmorphic features
- developmental delay
- normal intelligence to mental retardation
- short stature
- failure to thrive
- progressive deterioration of health status
- seizures
Genotypic presentation refers to diagnostic characteristics

Question 2

Klinefelter’s syndrome (XXY syndrome)

Answer 2

• Extra X chromosome, occurs only in males
• Not inherited
• Appears normal at birth, presenting in puberty
• May present initially as infertility
• Most common cause of hypogonadism and infertility in men
• Phenotypical manifestation: tall stature, transverse crease (as in down’s), abnormal body proportions, underdeveloped secondary sexual characteristics, gynecomastia, learning disability, personality impairment

Question 3

Turner’s syndrome (XO karyotype)

Answer 3

• Most common sex-chromosome anomaly of females
• 95% of embryos do not survive to term
• Typical findings: lymphedema, webbed neck, low hairline, learning disabilities, lack of secondary sex characteristics, “shield” shaped chest [widely spaced), variety of head/ neck abnormalities, hypertension, aortic arch abnormalities, Hashimoto thyroditis

Question 4

Which of the following ongoing assessments have no specific indication for individuals with Turner’s syndrome?

a. Cardiac monitoring
b. Vision screening
c. Tanner staging
d. Thyroid screening

Answer 4

b. vision screening

Question 5

Marfan syndrome

Answer 5

• Inherited connective tissue disorder affecting skeletal, cardiac, and ophthalmic body systems
• Cardiovascular: aortic regurgitation, mitral valve prolapse - no participation in contact sports
• Tall stature, arm span exceeds height, thin extremities and fingers
• long narrow face
• Pectus carinatum or excavatum
• Hyperextension of joints
• Genu recurvatum
• Kyphoscoliosis
• High arched, narrow palate
• Eyes: ectopia lentis, iridonesis

Question 6

DiGeorge (velocardiofacial) syndrome

Answer 6

• Congenital defect of the parathyroid glands, thymus, and the conotruncal region of the heart
• Increased susceptibility to infection (due to thymus aplasia)
• Abnormal facies: lateral displacement of inner canthi, short palpebral fissures, short philtrum, micrognathia, ear anomalies
• Congenital heart defects (aortic arch anomalies)
• Hypoparathyroidism with hypocalcemia - seizures in infancy
• Cognitive/ behavioral psychiatric problems
• Significant neonatal morbidity and mortality dt cardiac defects