The ppt explains the common type of genetic disorder in the easiest way with their respective karyotype.
Klinefelter’s syndrome: 44A + XXY (47)
Turner’s Syndrome: 44 + X chromosome
Edward’s Syndrome: 47 XX / XY
Patau’s Syndrome: 47 XX / XY
Down Syndrome: 45 A + XX or 45 A+ XY
Cri-du-cat Syndrome: 44 XX/XY
2. Chromosomal Genetic Disorder
• In these disorders, entire chromosomes, or large segments of them, are
missing, duplicated, or otherwise altered.
• Can be organized into two basic groups:
1) Numerical Abnormalities: When an individual is missing either a
chromosome from a pair (monosomy) or has more than two
chromosomes of a pair (trisomy)
2) Structural Abnormalities: When the chromosome's structure is
altered.
3. Klinefelter’s syndrome
• Also called as seminiferous tubule disgenesis or testicular disgenesis.
• Incidence:
– 1 in 5000 newborns
• Phenotype:
– At birth – identified as male
– Secondary sexual characters does not formed – infertility
– Paged voice
– Individual taller than others, slight mental retardation, severe personality
disturbance
4. • Cytogenesis:
– Egg having XX chromosome fertilized with sperms having Y chromosome/ egg
having X chromosome fertilized with XY chromosome sperm.
– Arise due to non-disjunction of paternal or maternal chromosome.
• Genotype:
– 44A + XXY (47)
5. Turner’s Syndrome
• Abnormality of sex chromosome also known as gonadal syndrome.
• Incidence:
– 1 in every 2500 new born babies(female).
• Phenotype:
– Low birth rate, growth retardation
– Facial abnormalities, epicanthial fold
– High arched palate, visual disablity, webbed neck.
10. • Cytogenesis:
– Trisomy in chromosome number 13 due to non-disjunction. Also
known as cleft syndrome.
• Genotype:
– 47 XX / XY
11. Down Syndrome
• Down syndrome is a developmental disorder caused by an extra copy of
chromosome 21 (which is why the disorder is also called "trisomy 21").
• Incidence:
– 1 in 100 births.
• Phenotype:
– Very distinct facial features:
• a flat face, a small broad nose, abnormally shaped ears, a large tongue,
and upward slanting eyes with small folds of skin in the corners.
– Increased risk of developing a number of medical problems:
• respiratory infections, gastrointestinal tract obstruction, leukemia, heart
defects, hearing loss, hypothyroidism, and various eye abnormalities.
12. • Cytogenesis:
– Having an extra copy of this chromosome means that individuals have three
copies of each of its genes instead of two, making it difficult for cells to properly
control how much protein is made.
– Producing too much or too little protein can have serious consequences.
– 95%: Non disjunction of maternal or paternal chromosome.
– 4% : due to translocation of long arm of chromosome number 21 and other
chromosome.
– 1% : Mosaicism with normal and trisomic cell line.
• Genotype:
– 45 A + XX or 45 A+ XY
13. Cri-du-cat Syndrome
• The name of this syndrome is French for "cry of the cat," referring to the distinctive cry of
children with this disorder.
• Incidence:
– 1 in 50,000 new borne. Predominance of female.
• Phenotype:
– The cry is caused by abnormal larynx development, one of the many symptoms
associated with this disorder.
– Babies with cri-du- chat are usually small at birth, and may have respiratory problems.
– Often, the larynx doesn't develop correctly, which causes the signature cat-like cry.
– Microcephalic
– Micrognathia
– Epicanthial folds
– IQ: less than 50
14. • Cytogenesis:
– Cri-du-chat is caused by a deletion (the length of which may vary) on the short arm of
chromosome 5.
– Multiple genes are missing as a result of this deletion, and each may contribute to the
symptoms of the disorder.
• Genotype:
– 44 XX/XY
