Below is a picture of a person’s chromosomes.  This picture is called a karyotype.  This picture is taken through a microscope after the white blood cells obtained from a blood sample have been carefully prepared in a lab. 

 

As you can see, there are 46 chromosomes.  These 46 chromosomes are arranged in pairs.  Therefore, we have 23 pairs of chromosomes.  We inherit one copy of each pair from our mother and the other copy from our father.  The first 22 pairs of chromosomes are arranged according to size.  These are called the autosomes.  The 23rd pair of chromosomes is known as the sex chromosomes.  These chromosomes determine a person’s gender.  Women have two X chromosomes and men have an X and a Y chromosome.  Because the karyotype above has an X and a Y chromosome, we know that it belongs to a male. 

“The above information is from the Chromosome 18 Registry & Research Society and was reproduced with permission.” Some minor changes may have been made to make the information as applicable as possible to 1p36 Deletion Syndrome.