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Related Disorders

The degree of the medical problems and disability can vary widely in children with a related disorder although they may have the same chromosome defect. 

This is because the genetic material that is extra or missing will be different in every case, and the professional opinion of a clinical geneticist should be sought.

Butterfly In The Wind
A child is a butterfly in the wind
Some can fly higher than others
But each one flies the best it can.
Why compare one against the other?
Each one is different
Each one is special
Each one is beautiful

Partial trisomy

In partial trisomy there is a small extra piece of a chromosome attached to another chromosome. This may be called an unbalanced translocation.

‘Hannah has partial trisomy 13 and we were given little hope of her survival in the early days, as the paediatrician assumed she had Patau’s syndrome, and we learned the truth only after insisting we saw a genetic consultant. The paediatrician still gave little hope of improvement long term, not believing she would ever support herself. Hannah now walks happily to school.’

‘Jonathan has a rare form of partial trisomy 18, and when he was diagnosed the consultant stressed how serious his particular condition was. Jonathan is now 19 years old. He has lived in a purpose-built residential home since 2000. The challenge now, is to move him to an adult centre being built 2007.’


Mosaicism means there is an error in the cell division after the fertilised egg splits into two cells.


There is an extra chromosome in some cells but not in others. The cells with 45 chromosomes die.

There is an extra chromosome in some cells but not in others. The cells with 45 chromosomes die.

‘We had a prenatal diagnosis of Mosaic 12 for Heather and the extreme rarity of the condition and the very poor prognosis were devastating. We refused the advice to terminate without further tests, opinions and research. Ultimately after five weeks we took the decision to continue the pregnancy. Heather is now 6 years old. She is beautiful to look at and has a bubbly, caring personality. She is doing very well at school and in her own words in her school report, “finds nothing hard.” We have moved since Heather was born and here her history is not known nor is it apparent in any way. No day passes without us remembering our good fortune and the support we received from SOFT in allowing ourselves time to reach our decision.’

NB 2010 Heather has just sat her A levels and has been offered a place at medical school.

‘Kyle was born in the July and we were still waiting for his chromosome results in December. By the time we were finally told he had mosaic 18 we had experienced the death of our dreams for the little boy we longed for. Kyle is now 10 years old and we no longer fear the present. He is a very special joy in our lives’.

‘We were told Danielle had trisomy 13 mosaicism when she was two weeks old and that she could live for weeks. Dani is now 7 years old and is a loveable little girl with heart and lung problems. She took her first steps before she was three’.

When a child with the full trisomy 13 or 18 does much better than expected, the explanation may be that there is a proportion of normal cells which the geneticist was unable to identify on the very tiny samples obtained and the child has a low level of mosaicism.

Ring Chromosomes

In rare cases chromosomes can form rings due to loss of genetic material from both ends of the chromosome. Cell divisions during the development of the embryo, fetus, child, and adult, may involve further damage to the ring chromosome, and generally this cell division happens at a lower rate and body growth is slowed.

‘Katy is nearly 9 years old and we were told she had ring 13 when she was 5 months old, and no clear picture of her future prospects. She needs no special nursing, just 24 hour attention on daily functions which are very slow.’

‘Tyanne has ring 18. She was bottle fed, which was very slow. At 6 months old I was unhappy and asked for an assessment. The paediatrician was good and we soon had a diagnosis. We spoon feed her, avoiding lumps as she cannot chew. Tyanne crawled at 10 months and is trying to pull herself up. She is small, has constant ear infections, a squint and a dislocated hip which they are correcting’.


A deletion means that there is part of a chromosome missing. The long arm of the chromosome is referred to as q and the short arm as p. A deletion of one of the long arms of chromosome 13 would be 13q-, and numbers can be used to specify exact areas of the chromosome.

‘Our son Joe had a deletion on one of the long arms of chromosome 13 (13q-). The effect of the deletion is still becoming apparent, notably small stature, hearing and visual difficulties, and mental handicap. He is not a ‘trisomy’ boy and is a happy, lively and well child.’

‘Jenny has a deletion of the short arm of chromosome 18 (18p-). She suffered badly from fits and GO Reflux. Since she has had the Nissan operation and a gastro tube, she keeps her food and her drugs down and the fitting is controlled completely. The operation has transformed her. She now plays with toys, laughs and is beginning to vocalise.’

Holoprosencephaly (HPE)

Holoprosencephaly is when the front part of the brain fails to develop into clearly separate right and left halves. Generally this severely affects the function of the brain, although among children with this condition there is considerable variability in the degree of malformation and its effects.

Babies diagnosed with this condition usually have a small head, excessive fluid in the brain, cleft lip, varying degrees of learning difficulties, epilepsy, hormonal problems, or problems with the heart, bones, bowel or bladder.

Although a baby with holoprosencephaly may not have abnormal chromosomes, it is common in trisomy 13.

‘Michael had holoprosencephaly and lived for 6 months. Throughout his life he was tube fed, and on medication to stop fits and GO reflux. He didn’t sleep much at night and we had frequent trips to hospital for respite care and illness. At 5 months he was unable to swallow mucus and we had to use a portable suction pump. One of my proudest moments was when I dressed him in a little sailor suit and walked through the hospital to the car park. Lots of people gave me admiring glances as though to say “What a lovely boy.’

‘James has holoprosencephaly. He takes his drinks from a bottle, but as he gulps he does get colic. He is constipated but will eat virtually anything, if mashed! He has regular physio for a slightly dislocated hip and to aid correct spine formation and posture. James is registered blind due to a damaged optic nerve. He still has the soft spot on top of his head. When it closes he may need a shunt inserted to drain fluid from the brain. He attends school and is now 4 years old.’

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