Diagnosis of CdLS
The diagnosis of CdLS is primarily a clinical one based on signs and symptoms observed through an evaluation by a physician, including a medical history, physical examination and laboratory tests.
Although three separate gene mutations have been identified as causing CdLS, not every person tests positive for one of these gene changes. If you suspect your child has CdLS, a genetic specialist can help.Request A Diagnostic Checklist
Frequently Asked Questions About Diagnosis
- Will all people with a CdLS diagnosis have one of the gene changes?
- Is there a test for CdLS?
- Can my child be tested? Can I be tested?
- What does a negative test result mean for my child?
- What are the long-term implications of gene discoveries?
- Prenatal Diagnosis of CdLS
Will all people who have the diagnosis of CdLS have one of the gene changes?
No. Currently, researchers find a gene change in about 60 percent of individuals with CdLS. A higher percentage may be identifiable as testing procedures become more sophisticated, and as additional gene mutations are identified.
Is there a test for CdLS?
Yes. Presently, the Children’s Hospital of Philadelphia (CHOP) and the University of Chicago Genetics Services Laboratory can test for “CdLS genes.”
Testing at the University of Chicago is done on a clinical basis. This means that only one blood sample is required, results are always reported to the ordering physician, and a fee is required (which may be covered by insurance). These results can be used for carrier testing or prenatal testing for other family members. Interesting findings from the clinical testing at the University of Chicago may be shared with the CHOP lab for research purposes.
CHOP provides testing for research purposes only, and no longer tests for NIPBL and SMC1A gene changes; rather, the lab is concentrating on finding additional CdLS genes. Your child may participate in testing at CHOP if he/she has a clinical diagnosis but previous blood tests have not confirmed gene changes in NIPBL or SMC1A. CHOP is also interested in families with multiple incidences of CdLS.
Can my child be tested? Can I be tested?
The first person to be tested in any family would be the individual with CdLS. Testing for changes in CdLS genes is complicated by the fact that the genes are very large. We use the analogy of reading a very long book (e.g. War and Peace) and looking for a single typographical error. You may read the whole book and miss the “typo,” however when you do find it then it is easy to test other family members (i.e. you know that the change is on page 875 in the second paragraph).
What does a negative test result mean for my child?
In cases where the diagnosis is doubtful, it may contribute additional evidence against the diagnosis; however even in individuals with classic features of CdLS, gene mutations are not always found.
What are the long-term implications of gene discoveries?
Now that the basic causes of CdLS has been discovered, we can begin to understand how these changes result in the clinical differences seen in affected individuals. By studying how this occurs, researchers can understand the clinical problems that individuals with CdLS face on a very basic level. With time, we hope this results in better care for affected individuals.
Research continues to support a low risk of reoccurrence, but for parents who have a child with CdLS, prenatal ultrasound can provide an evaluation of subsequent pregnancies. An initial ultrasound examination is recommended for all subsequent pregnancies at 18 weeks. The timing of this scan allows a thorough study of the anatomy of the fetus and accurate dating of the pregnancy. In addition to the routine survey, carefully attention should be made to the face, hands, heart, arms, and ventricles of the head. Anatomic abnormalities that have been described on prenatal studies of babies with CdLS include: limb abnormalities (particularly of the upper limbs), abnormal hearts, cleft lip, abnormal facial profile, diaphragmatic hernia, mild enlargement of the ventricles of the head, and gastrointestinal abnormalities.
The most distinctive of these abnormalities are those of the upper limb. Arm bones and fingers should be carefully examined and counted because these may be missing or abnormally short. The femur, feet and arm bones should be measured to ensure that their lengths are within the normal range. In the face of a fetus with CdLS, one might find cleft lip or palate, long eyelashes, a small chin, and a small upturned nose. The head tends to be short and small (microbrachycephaly) and should be measured and compared to tables of non-normal measurements. In many of the children, there are abnormalities of the heart and sometimes a diaphragmatic hernia or abdominal calcification (meconium peritonitis).
Ultrasound is not a perfect tool to diagnose CdLS, nor is it a perfect tool to exclude the possibility of CdLS. Nonetheless, most children with CdLS have fairly severe abnormalities that can be detected prenatally by careful radiologists or obstetricians.