GENETICS

on average, any two individuals share 99.9% of their DNA sequences. Thus, the remarkable diversity of humans is encoded in about 0.1% of our DNA.

FIRST DISEASE IN WHICH GENE THERAPY IS USED--- SEVERE COMBINED IMMUNODEFICIENCY DISEASE (SCID).

Autosomal monosomies are incompatible with fetal development.

Only monosomy compatible with live birth is due to involvement of sex chromatin- turner syndrome(45X)

 Disease with multifactorial inheritance-

Coronary heart disease, diabetes mellitus, cleft lip/cleft palate, hypertension, gout, pyloric stenosis, congenital heart disease.

Prader willi syndrome- paternal genomic imprinting and maternal uniparental disomy (both allele of gene comes from same parent either mother or father).

Autosomal dominant disorder with phenotypically normal parents have more than one affected child-  germline mosaicism.

Karyotyping is not done with the blood monocyte.

Karyotyping with light microscopy is done by- G banding(Giemsa banding)

DNA fragmentation in apoptosis is detected with the help of-  TUNEL( Terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate insitu nick end labelling).

Inheritance pattern of blood group system – by CODOMINANCE

Gene regulating normal morphogenesis during developmentis- Homeobox gene

Most common type of genetic polymorphism- single nucleotide polymorphism(SNP)

Study of multiple genes- Microarray

Blotting techniques-

southern blot- for DNA

Northern blot- for RNA

Western blot- for protein

Chromosomal abnormalities in down syndrome-

Trisomy 21(95%)- maternal non disjunction most common cause

Mosaicism(2%)

Robertsonian translocation(3%)- transfer of genetic material between two metacentric chromosomes.

Lawrence moon biedel syndrome- mental retardation, retinitis pigmentosa, polydactyly, hypogonadotropic hypogonadism, obesity( not asthenic)

Mc cune Albright syndrome- polyostotic form of fibrous dysplasia, pigmentation, precosious puberty(3p), mutation in GNAS α.

Most common cause of ambiguous genitalia in females- complete or classic 21α hydroxylase deficiency.

Rokitansky kuster hauser syndrome- vaginal atresia, absent uterus.