Human Cytogenetic Analysis

This set of links will take you through an introduction to cytogenetic analysis. It is suggested that you review meiosis and mitosis before proceeding. It will also help if you have an understanding of some basic chromosome abnormalities (aneuploidies, translocations etc.) You may work your way through the introduction or you may go straight to trying your hand at completing normal or abnormal karyotypes.

Introduction

Introduction to chromosome morphology

Chromosome morphology quiz

Karyotyping Process I, Arrangement of the karyotype form.

Karyotyping Process II, Placing the chromosomes on the form.

Normal Karyotypes

Try your hand with normal karyotyping by completing one or both of these partial karyotypes. Line up homologous chromosomes by clicking on those chromosomes at the bottom of the window and dragging them to their proper position. A proper match will be acknowledged while mismatch will not. Remember, that in mammals, the female is the homogametic sex (XX) and the male is the heterogametic sex (XY). Determine the sex of each of these individuals.

This phenotypically normal patient was referred because of a nephew with downs syndrome shown to be the result of a robersonian translocation, 46, XY, -14, +t(14;21). The sister of the patient was shown to be a balanced carrier of this translocation; 45, XX, -14, -21, +t(14;21) [Full Size] [Smaller]

This 25 year old phenotypically normal patient has a severely dismorphic son who, upon karyotypic analysis, was shown to have a partial trisomy of chromosome 6 resulting from a translocation; 46, XY, t(3p;6p). The patient was referred to rule out being a carrier for a balanced translocation. [Full Size] [Smaller]

Abnormal Karyotypes

The following patients were referred for cytogenetic analysis based on their clinical symptoms or phenotypes. Complete one or more of these partial karyotypes then make a diagnosis of the chromosomal abnormality.

A 27 year old male of tall stature was referred for mild mental retardation to rule out Fragile X syndrome [Full Size] [Smaller]

A blood sample was from a newborn with multiple congenital anomalies including hypertlorism, cleft lip and palate, polydactyly, and clenched fists. [Full Size] [Smaller]

This blood sample was taken from a one day old infant girl with severe congenital anomalies including rocker bottom feet, receding jaw, malformed and low set ears, and short sternum. [Full Size] [Smaller]

A blood sample taken from a 16 year old man with mental retardation, macro orchidsm, large ears and hypermobile joints. [Full Size] [Smaller]

An amniotic fluid sample was received from a 32 year old woman who was 27 weeks pregnant. An ultrasound had found her fetus to have a sloped forehead, a splayed spine, a small jaw and cystic kidneys. [Full Size] [Smaller]