Class II & III muations

Question

I am fairly new to learning about CF but have accepted the baby has this and the mutations are Class II & III. The little one is now 6 months and 2 wks old and so far the health has been excellent, not even a sllight cold. The weight gain on average is about 0.64grms per week and his CF clinic are happy with this. He has been on an antibiotic twice daily since diagnosed at 3 weeks and physio twice daily. His motions are normal and started weaning at 20 weeks and Creon not as yet required. I understand that suddenly problems could arise and no doubt will but does this seem a fairly promising beginning for someone with these mutations? When reading about CF and jumping on the CF Forum I can't help but note that most other babies with classic mutations are showing some early symptoms. Being salty has never been an issue either. No sweat test has been carried out but the faulty genes have been identified in myself and my husband and also 2 of my 3 brothers so it is conclusive. Thank you.

Answer

Hello
In CF there is often not a good correlation between genotype (the genes
a person has) and the phenotype (how a person actually is).
Generally Class I-III mutations are associated with pancreatic insufficiency and class IV and V mutations with pancreatic sufficiency, even if those correlations are not absolute and exceptions are possible.
Patients identified by neonatal screening and who carry class I-III mutations on both alleles may be pancreatic sufficient at diagnosis, but are likely to develop PI within the first 1-2 years of life, requiring enzymes then. There is a test available, although not in all laboratories, which measures faecal pancreatic elastase - 1, this can help to make the decision as to whether or not enzymes are needed.
The most important thing to ensure is your baby's intake is adequate and
the height and weight are regularly plotted on the appropriate centile
charts e.g. 1990 Nine Centile United Kingdom Charts. Digestive problems
in CF rarely arise suddenly. If a person is not absorbing properly,
despite adequate intake, there will be a gradual downward trend on the
centile chart.
A weight gain of 64g/week seems just a little low. The expected weight
gain during the first year of life is approximately:
200g/week 1-3 months
150g/week 3 -6 months
100g/week 6- 9 months
75g/week 9-12 months
All treatment in CF is preventative - enzymes if needed to prevent
malabsorption and physiotherapy and long term antibiotics to prevent
lung infections. With this treatment we would not expect sudden
deterioration in respiratory symptoms. However CF babies like all babies
are prone to picking up viral infections which may result in some
problems for example coughing and wheezing.
The risk of a secondary bacterial infection after a viral infection is
high therefore a bacteriology screen (cough swab) and a change in
antibiotic is recommended.
Overall CF is such a variable condition and the gene can be modified by
various environmental factors. Ensuring your baby is well nourished and
has no bacterial growth in the lung secretions is giving him the best
start in life.
References
Cystic Fibrosis Trust Nutrition Working Group. Nutritional Management of
Cystic Fibrosis. London.
Cystic Fibrosis Trust, April 2002.
Brunner L S, Suddarth D S. The Lippincott manual of Paediatric Nursing.
Harper & Row, 1991.

Best wishes
Hazel Mills
CF Nurse Specialist.

20.02.2012

The answer is edited by: Prof Stuart Elborn