FISH

SMALL SUPERNUMERARY MARKER CHROMOSOMES

-  sSMC -

BASICS - EUCHROMATIN

 

Euchromatin present on and sSMC

 

Euchromatin is genetic relevant material and to be distigished from heterochromatin. The latter does not include any genes. #
sSMC may consist of both: eu- and heterochromatin.

Strikingly euchromatin can be present on an sSMC and must not cause any harm in the carrier. It depends which exact genetic imbalance was induced. Thus, a detailed sSMC characterization is necessary esp. in prenatal cases!!

 

Euchromatin was detected or excluded on sSMC by different methods:

- Replication banding {49}

- C-bands {58-59}

- DA/DAPI staining for characterization of chromosome 15 - however, its abilities have been questioned {60-63; 75}

- Rx-FISH {50}

- micro dissection and reverse painting (e.g. {51})

- FISH using locus specific probes (e.g. {52})

- association of sSMC with centromeric regions - the more heterochromatin they consist of the better they associate {82-87}

- array-CGH studies (e.g. {173})

 

References