Cytogenetics

Chromosomes carry our genetic material (genes).

Humans usually have a set of chromosomes consisting of 46 chromosomes: 22 pairs of autosomes and 2 pairs of sex chromosomes (XY in men, XX in women).

Deviations from the normal number or structure of chromosomes (chromosomal aberrations) occur in approximately 0.5 % of all live births. Chromosomal aberrations can be analysed before a child is born, i.e. prenatally.

Indications

Frequent indications of chromosome analyses include:

  • unclear intellectual disability or developmental delay
  • multiple congenital malformations
  • leukemias
  • women with a short stature of unknown cause
  • subfertility/infertility
  • familial chromosome changes
  • repeated miscarriages
  • during pregnancy:
    • advanced maternal age, ultrasound abnormalities
    • unusual results of biochemical tests such as first trimester screening, integrated screening

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Sampling / shipping

Prenatal chromosome analysis using:

  • Amniotic cells
    approx. 10 – 15 ml. Discard the first 2 ml. Store and transport at room temperature. Never centrifuge!
    Register sample by phone  (+49 6132 781 411) / Fax  (+49 6132 781 194) with the Client Service of Human Genetics
    Duration*: 8 – 10 days
  • Chorionic villi (CVS) 
    min. 20 – 30 mg chorionic villi,
    Use sterile transport medium (available upon request)
    Register sample with the Client Service (see above) by telephone or fax.
    Duration*: direct preparation 1 – 2 days; culture 8 – 10 days
  • Cord blood
    2 – 3 ml cord blood in lithium heparin tube. Additionally, the Kleihauer-Betke test is conducted.
    Duration*: 7 days
  • Abortion material
    Material: chorionic villi, sections of the umbilical cord, Achilles tendon or fascia lata, use sterile transport medium (available on request)
    Alternatively: sterile uncoated tube with physiological NaCl with antibiotics addition (penicillin (100µg/ml), streptomycin (100µg/ml) or gentamycin (50µg/ml)). Do not put in formalin!
    Duration*: 10 – 14 days

Request form: Prenatal diagostics

Postnatal chromosome analysis using:

  • Lithium heparin blood
    Adults: 5 – 7 ml
    Children: 5 – 7 ml
    Newborns: 1 – 2.5 ml
    Duration*: 10 – 14 days; urgent cases: 5 – 7 days
  • Fibroblasts, skin approx. 5 mg tissue, sized 2 – 10 mm2 in sterile transport medium (available on request). Do not put in formalin!
    Duration*: 10 – 14 days

Request form: Postnatal chromosome diagnostics

The following aspects have to be considered:

  • Genetic counselling and testing do not burden your laboratory budget.
  • To request a molecular or cytogenetic laboratory test, the laboratory form, template 10 with indication of the suspected diagnosis is required.

Duration* = Processing time after arrival of the sample in the laboratory

 

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