Genetics

Cytogenetics is a branch of genetics. Every individual has 46 chromosomes with XX sex chromosomes in females and XY in males. These chromosomes are carriers of the genetic material that encodes for all genetic information. Thus any abnormality in the chromosome number or structure leads to a genetic condition with mild to severe clinical presentation depending on the type of chromosomal abnormality.

Chromosomal abnormalities can happen in any cell in the body when egg and sperm cells are being made, during early fetal development, or after birth. A routine cytogenetic analysis involves evaluating 15 to 20 cells to determine their modal chromosome number and assessing the structural integrity of each chromosome in the complement. Thus, cytogenetics has a direct effect on the diagnosis, management, and prevention of many disorders that are caused by chromosome aberrations.

The cytogenetics department at CIMAR has the best cytogenetics lab that work together with maternal-fetal medicine department and infertility department.

Who benefits cytogenetics testing?

The cytogenetics testing involves prenatal diagnosis, neonatal and paediatric investigations for recognised syndromes, investigation of developmental delay, learning difficulties, multiple congenital abnormalities (dysmorphism), investigation of infertility and reproductive disorders in adults. In conjunction with collaborating laboratories, we also undertake specialist cytogenetics testing for rarer genetic syndromes.

Cases referred for chromosomal analyses (cytogenetics testing) include a wide range of individuals with the following clinical conditions:

• Adults with history of spontaneous abortions, repeated miscarriages, infertility.
• Neonatal and pediatric group of patients with complex conditions like mental retardation, learning disability, developmental delay, autism, congenital malformation, ambiguous genitalia etc.
• Prenatal diagnosis (amniocentesis, CVS and cord blood by FISH and Karyotyping) in cases with suspected genetic abnormalities in the fetus, advanced maternal age and/or abnormal biochemical triple test.
• Detection of carrier status in parents of a child with known chromosomal abnormality, to understand the inheritance pattern and to decide upon the risk factor for subsequent pregnancies.

Parental cytogenetics testing

Parental cytogenetic testing may be requested following the conception of a cytogenetically abnormal fetus, the birth of a cytogenetically abnormal child, the loss of a pregnancy with a suspected chromosome abnormality, or an unexplained stillbirth/neonatal death. Samples can be referred for a wide variety of reasons (see below):

• Parental karyotyping after pregnancy loss of a fetus <24 weeks with multiple congenital abnormalities or severe IUGR, or unexplained stillbirth/neonatal death >24 weeks.
• Cytogenetics testing following MLPA/QF-PCR testing of products of conception if an unbalanced structural chromosomal abnormality is identified or a result is not obtained for technical reasons i.e. a sample was received but failed to produce a result.
• Testing after three or more unexplained miscarriages.
• If there have been two identical aneuploidies suggesting parental mosaicism.
• Following an abnormal cytogenetic result in a fetus or child NB the proband’s report will state if parental cytogenetics testing is indicated.

Following an abnormal cytogenetic result in a fetus or child NB the proband’s report will state if parental cytogenetics testing is indicated.

Our fully equippedcytogeneticslab aids both the maternal-fetal medicine unitand theinfertilityunit.

CIMAR cytogeneticslab offers the following services:

• Genetic Counselling
• Premarital Counselling People with family/personal history of structural/mental abnormalities with/without consanguinity are offered counseling regarding the risk they carry for a particular disorder.
• Antenatal Counselling A woman with an USG detected fetal anomaly scan is counseled regarding the prognosis of her pregnancy and the probability of having a similar anomaly in the future.
• Work up of the Index Child Any woman with an affected child is offered detailed work up of the child by a team of dysmorphologists and geneticists to reach an accurate diagnosis which may predict the prognosis.