Genetic & Congenital Disorders

Explanation -
Causes of down syndrome -
Non dysjunction ( 94%)
Mosaicism ( 2%)
Robertsonian translocation ( 4%)

Explanation :
Congenital cyanotic heart disease :
Fallot's tetralogy
Transposition of the great vessels
Severe ebstain anomaly
Tricuspid atresia
Pulmonary atresia
Severe pumonary stenosis

Congenital acyanotic heart disease -
ASD
VSD
PDA
Coarctation of aorta
Congenital aoryuc stenosis

Explanation :
Barr body :
Tightly coiled clump of chromatin
Found microacopically in interphase of cell
Presents in lining of the check ( buccal mucosa)
Absent in normal male

Explanation :
Defect in hormone :
Achondroplasia 
Hypochondroplasia
Osteopetrosis
Thalantophoric dysplasia
Defect in extracellular structural proteins -
Osteogenesis imperfecta

Explanation :
Mostly all autosomal recessive disorders are related to enzyme.

Explanation :
Autosomal dominant inheritance -
At least one parent of a case is affected
Both male and female canbe equally affected.
Consecutive generations are affected
Presents in heterozygous state

Ehlers danlos syndrome is a condition where there is poorly developed collagen,easy to hurt,poor healers,cigarette paper like skin known as rubber man or human pretzels. 

Explanation: Hypertrophic cardiomyopathy results in diastolic (relaxation) dysfunction. Virtually all cases are due to autosomal dominant mutation

Explanation :
The 4 cardinal features of TOF -
1. VSD
2.Obstruction of the right ventricular outflow tract
3.An aorta that overrides the VSD
4.Right ventricular hypertrophy 

Explanation :
Multifactorial ( polygenic)  inheritance disorders -
Cleft lip and or palate
Congenital dialocation of hip
Congenital heart defects
Gout
Hypertension 
Diabetes
Neural tube defects

Explanation :
Imprinting disorders -
Beckwith wiedermann syndrome
Prader willi syndrome 
Anglemann syndrome

Explanation -
The expression of the defect tends to be more uniform than in autosomal dominant disorders.
• Complete penetrance is common.
• Onset is frequently early in life.
• Although new mutations associated with recessive disorders do occur, they are rarely detected clinically.
Since the individual with a new mutation is an asymptomatic heterozygote, several generations may pass before the descendants of such a person mate with other heterozygotes and produce affected offspring.
• Many of the mutated genes encode enzymes. Occurs due to defect in enzymes.

Explanation :
Approximately 40% of the patients have congenital heart disease. The most frequent forms of congenital heart diseases in Down syndrome are atrioventricular septal defects constituting 43% of cases, whereas ventricular septal defects, atrial septal defects, and tetralogy of Fallot also involved.
Children with trisomy 21 have a high risk of developing leukemia; there is 20-fold increased risk of developing acute B lymphoblastic leukemias and 500-fold increased risk of acute myeloid leukemias. The latter, most commonly, is acute megakaryoblastic leukemia.
• Virtually all patients with trisomy 21 older than age 40 develop neuropathologic changes characteristic of Alzheimer disease, a degenerative disorder of the brain.
• Patients with Down syndrome have abnormal immune responses that predispose them to serious infections, particularly of the lungs, and to thyroid autoimmunity, causing hypothyroidism .

Explanation :
Female pseudohermaphrodite -
Gonads : Ovary
Karyotype : 46,XX
Secondary sexual organ incomplete or ambiguous 
Cliteromegaly found
Excessive androgen found.

• Left-to-right shunts are most common and are typically associated with ASDs, VSDs, or a PDA.

Explanation: VSD is the most common congenital heart disease

Explanation :
DNA -
a polymer composed of two polynucleotide chains that coil around each other to form a double helix.
The polymer carries genetic instructions for the development, functioning and growth.
Each nucleotide is composed of one of four nitrogen-containing nucleobases (cytosine [C], guanine [G], adenine [A] or thymine [T]), a sugar called deoxyribose, and a phosphate group.
Purin base - Adenine and guanine
Pyrimidine base - Cytosine,Thymine,Uracil

Explanation :
Sex chromosomal aneuploidy :
Turners syndrome : 45,XO
Klinfelters syndrome : 47,XXY
Super female : 47,XXX

Explanation :
Frequencies -
VSD - 42%
ASD - 10%