What is Wolf-Hirschhorn Syndrome?
Hugo was born with a very rare genetic condition called Wolf-Hirschhorn syndrome. This syndrome is caused by a deletion (missing section) of the short (p) arm of the 4th chromosome (the syndrome is sometimes referred to as “4p”) and is estimated to occur in 1 in 50,000 births. The size of the deletion varies among affected people, but research has suggested that the deletion size is highly correlated with the level of intellectual disability and physical abnormalities (i.e. the larger the deletion, the more severely affected an individual will be). Wolf-Hirschhorn syndrome can be caused either by a child inheriting a chromosomal translocation from a parent, or can be a random genetic event (called a ‘de novo deletion’). A genetic test of the parents is done to establish which form a child receives, in order to understand the risks associated with having further children. Genetic counselling and testing undertaken shorted after Hugo’s birth determined his is a de novo case.
How does Wolf-Hirschhorn syndrome affect Hugo?
As stated, the size of the genetic deletion is generally correlated with how affected a person is by the syndrome, but almost all children with Wolf-Hirschhorn syndrome have a number of characteristics in common including; prenatal growth deficiency followed by postnatal growth retardation, a particular facial appearance (they call this the “Greek warrior helmet”), low muscle tone (hypotonia) delayed growth and development, intellectual disability and seizures. Hugo has all of these symptoms, although for the moment his seizures are largely managed well with medication.
Hugo has a particularly large deletion and is thus affected quite severely by the syndrome in a number of complex ways. His developmental and intellectual disabilities are significant and, in addition to the issues mentioned above, he also has a number of other medical issues that are commonly seen in people with Wolf-Hirschhorn syndrome including:
- Small eyes, particularly of the right eye which did not form at all (micropthalmia)
- An ocular prosthesis (prosthetic eye) in the eye that did not form - this helps his face to continue to grow around the eye socket correctly
- Structural issues with his ‘good eye’ (e.g. coloboma), meaning he has very little vision from this eye.
- Poorly formed ears with small holes (pits)
- Small chin (microgathia)
- Unusually small head (microcephaly)
- Slow growth, that began before birth and for a long time affected his ability to gain weight (failure to thrive).
- At age four he is now average height for his age (50th percentile) and within the bounds of normal for weight (30th percentile). These are measurements both taken on the normal height/weight scales, not the Wolf-Hirschhorn Syndrome.
- Nasal gastric feeding tube (from about 2 years to 3 ½ years) - prior to that Hugo did suck a bottle and had started solid feeding but he has lost those skills for the moment
- PEG feeding tube (inserted by operation when he was 3 ½ years). His weight and height gain as improved dramatically since the insertion of the PEG.
- Low muscle tone (hypotonia) and underdeveloped muscles
- Severe to profound developmental delay (Hugo enjoys being vocal, but has no words)
- Severe to profound intellectual disability (at age 4 he shows recognition of his close family and friends and is learning to follow some simple commands, e.g. ‘head up’ and ‘clap hands’. He is very sociable and particularly enjoys the company of others and listening to music and stories).
- Severe physical disability (at age 3 1/2 he was just learning to sit up and place weight through his legs. At age 4 he took a few steps without support from a standing frame)
- Cleft palate (repaired around 9 months old)
- Hypospadias (two stage repair when he was a baby)
- Hernias (repaired when he was a baby)
- Complex seizure disorder that he had for many years. He hasn't had a seizure since he was 3 years old but they started around 6 months and he has had a number of substantial tonic/clonic seizures and for a long time he also suffered from myoclonic jerks until the correct medications could be established.
- Reflux (controlled by medication as needed)
Many children with Wolf-Hirschhorn syndrome, particularly those with large deletions like Hugo, also suffer from congenital heart defects and renal abnormality, however Hugo was lucky enough to escape these particular issues.