How is an FG Syndrome diagnosis made?
The diagnosis is typically made by a geneticist who is familiar with the syndrome, who may recommend a blood test to determine if your child has “FGS1″ (see FAQ “Is there a test for FG Syndrome?”). However, if your child tests negative for Opitz-Kaveggia Syndrome, or “FGS1,” an FG diagnosis may be made based upon a clustering of specific symptoms. Some believe that any boy with hypotonia, chronic constipation and developmental delay should be evaluated for FG Syndrome. Some who study the syndrome believe it is actually a common syndrome. They believe it may be accountable for many unexplained X-linked mental retardations, and also describe emerging evidence that suggests there may be many men who are affected by the syndrome that are considered “typical” and as a result do not know they have FG Syndrome. This suggests that there is a wide range of functional capacity for those with the syndrome. Other evidence suggests that some children who are diagnosed with autism spectrum disorder may actually be affected by FG Syndrome.
With the enormous amount of progress made in the past decade in the field of genetics, there have also been huge improvements in the tools that are used to test DNA. Thus your geneticist might also consider additional chromosomal testing, such as a subtelomere FISH panel, or Comparative Genomic Hybridization (CGH) study, which would rule out other chromosomal anomalies that sometimes present with similar traits to FG Syndrome.
If blood tests are recommended for your child, and to avoid the necessity of additional blood draws in the future should you receive inconclusive or negative results; you may want to discuss with your doctor the possibility of storing enough additional blood for future testing for FG Syndrome phenotype, or for other possible considerations, as new testing becomes available.