Life expectancy of treated individuals appears to be normal. Some researchers report that neurological complications such as seizures, loss of control of voluntary movements and intention tremor become more prevalent with age. The cause of the symptoms is not clear. Inheritance patterns Autosomal recessive Pre-natal diagnosis Chorionic villus sampling at ten to twelve weeks with amniocentesis at 16 weeks if necessary The information below has been drawn up by Dr Orlee Udwin of the Society for the Study of Behavioural Phenotypes. Even with early diagnosis and immediate treatment psychological and learning difficulties are apparent.
Intellectual abilities tend to be in the low average or borderline range.
Even children with average cognitive abilities have a high prevalence of speech and language problems. These are most marked in the area of expressive language, and include a limited vocabulary, difficulties with word finding, syntax and grammar, articulation disorders, and transpositions of words in sentences. Deficits in verbal recall and problems with abstract reasoning have also been described. In contrast, understanding of language tends to be age appropriate. There are reports of progressive neurological disease and a decline in IQ scores in affected individuals with increasing age, though the latter may be due to the use of different cognitive assessments at different ages.