Understanding 10p deletions ...

Some of you may not at all be interested in the information I have attached but I know some where asking if I had addition literature on some things... so this is what I have. I also will be posting some information on how her 20p13 duplication is said to effect her in the future. Genetics to most people is not all that interesting. However, I wanted to put it out there for those who were requesting it.

I realize that I haven't taken a lot of time to actually explain the basics of Emma's chromosome abnormalities... I know I have mentioned a few things and briefed you all on it but I wanted to give you an overall... "research" point of view... This is based off 10p deletions, not just 10p13 deletions. Its a basic overview of information on deletions of the 10th chromosome. Most of the information acquired I link to Unique because that has been a huge help in me understanding things. Therefore, that is the information I use to help explain things for you.


Emma's Chromosome Abnormalities:
      - 10p13 terminal deletion
         -20p13 duplication


10p deletions

A chromosome 10p deletion means that part of one of the body’s chromosomes has been lost or deleted. If the missing chromosome material contains important instructions for the body, learning difficulties, developmental delay and health problems may occur. How serious these problems are depends on how much of the chromosome has been lost and where the deletion is.

　

Genes and chromosomes

Our bodies are made up of billions of cells. Most of the cells contain a complete set of
tens of thousands of genes. Genes act like a set of instructions, controlling our growth and development and how our bodies work. Genes are carried on microscopically small, thread-like structures called chromosomes. There are usually 46 chromosomes, 23 inherited from our mother and 23 inherited from our father, so we have two sets of 23 chromosomes in ‘pairs’. Apart from two sex chromosomes (two Xs for a girl and an X and a Y for a boy) the chromosomes are numbered 1 to 22, generally from largest to smallest. Each chromosome has a short arm (at the top in the picture below) called p from petite, the French word for small, and a long arm called q (at the bottom). In a 10p deletion, material has been lost from the short arm of one of the two chromosome 10s. You cannot see chromosomes with the naked eye, but if you stain them and make their image about 1,000 times larger with a computer or under a microscope, you can see that each one has a pattern of light and dark bands. A small piece or a large piece of the chromosome can be missing. Sometimes it can be identified under a microscope or on a computer. The missing piece may be so tiny that it can only be identified using new technology with tests such as FISH or array-CGH. It is then called a microdeletion. One type of deletion is called terminal. The chromosome has broken in one place and the part of the chromosome from the breakpoint to the end of the arm is missing. Another type of deletion is called interstitial. There are two breakpoints on the same arm that have rejoined and the part of the chromosome between them is missing.

                                          How do we know about the effects of a 10p deletion?

Your genetic specialist can tell you more about the chromosome material that has been lost. You will almost certainly be given a karyotype, a short hand code for your child’s chromosomes that shows the points where the chromosome has broken and rejoined.

People with a 10p deletion may have the same break in their chromosomes or a similar one but they do not all have the same problems or features. There will be differences between your child and others with apparently similar chromosome changes and these differences can be quite marked. It is very important to see your child as an individual and not to make direct comparisons with others

After all, each of us is unique. But some features and health problems are similar in people with a 10p deletion. It is hard to be certain then about the effects but as more people are diagnosed, the picture will hopefully become clearer. The oldest child with the disorder known to Unique is in her late teens
and the group has one affected adult member, but it is likely that there are many older people with a 10p deletion.

                                                     Deletions from 10p12, 10p13 or 10p14

Among babies and children with a breakpoint at 10p12, 10p13 or 10p14, features such as some delay in development are consistent and a slow pattern of growth and an unusual look to the face are common. However, individuals vary widely, both in the ways they are affected and the severity of the effects. As a broad generalisation, where the breakpoint is in band 10p14, and especially if the chromosome has broken near to band 10p15, the effects are milder.

Within band 10p14 there is a gene known as GATA3 and when this gene has been interupted or is missing, a child is likely to show one or more of the three hallmark features of HDR syndrome. H stands for hypoparathyroidism. Children often have low calcium levels. D stands for deafness, usually a partial hearing loss that is present from birth and affects both ears. R is for renal. The kidneys may be small, abnormal or one may be missing or there may be urinary tract abnormalities.

A little closer to the centromere (the point where the short arm meets the long arm) there is a region of 10p known to be important for the normal development of the heart and the cells known as T-cells that help to fight infections. This region is known as the DiGeorge critical region 2 (shortened to DGCR2) because babies and children who have lost important genes from this region have similar clinical problems to babies with a condition known as DiGeorge syndrome. However, DiGeorge syndrome proper is caused by the loss of a tiny amount of chromosome material from the long arm of chromosome 22. The geneticist or paediatrician who tells you about your child’s chromosome disorder should be able to tell you whether your child has lost GATA3 or the DGCR2.
                                                                      Appearance
To parents, a baby with a 10p deletion may look little different to other babies. Nonetheless, if you meet another affected family, you may notice some similarities between your child and theirs. Any similarities are likely to be less easy to interpret if your child has a 10p deletion as part of a more complex chromosome rearrangement..
This picture was taken back in June....but its a happy picture!
Thanks again, for taking the time to read through Emma's blog, pray for Emma, and most importantly thank you for letting Emma's Story inspire you! :) Have a blessed day!