Some families clearly have genetically determined CTS with it behaving as an autosomal dominant trait though no gene has been identified. These families are characterised by usually presenting with CTS at an early age, often before twenty. A useful summary of some of the genetic literature relating to families with obviously genetic CTS can be found online at Online Mendelian Inheritance in Man. Such families are very rare however and are something of a side issue for CTS in general.
The well known genetically determined condition ‘Hereditary Neuropathy with Liability to Pressure Palsies’ (HNPP or HLPP) for which the gene is known also accounts for a very small number of CTS cases and some inherited syndromes with many complex clinical features such as the mucoplysaccharidoses have carpal tunnel syndrome as one of their many manifestations.
Of more general interest however is the fact that there clearly is a substantial genetic contribution to more ‘ordinary’ CTS. A study performed on the St Thomas’s Hospital twin register came to the conclusion that as much as half of the overall causation of CTS, at least in women, could be attributed to genetic factors, but not to a single gene - it is a combination of the effects of many genes (Hakim 2002). In other words a major contributor to whether any given individual gets CTS is the way they were built in the first place - but ‘built’ in this context is not confined to physical structure, genetics also determines your biochemistry.
Race - closely allied to the issue of genetics, there may be racial variations in the incidence of CTS. It has been suggested that there is a lower incidence of CTS in people of black African/West Indian origin but the relatively small number of studies which suggest this (Goga 1990, Garland 1996) have some methodological flaws and in any case it is difficult to separate cultural and social differences in the ways people present for medical care from truly racial variations. It has become more difficult to study such issues since, for 'political' reasons, few records systems include details of race.
Revision date - 12th March 2013