The legal impasse with the in-vitro fertilisation mix-up case here has undoubtedly caused much anguish to the parents and child concerned ("Still no decision on whether parent is entitled to damages"; last Friday).

Although the Ministry of Health (MOH) has tightened procedures to prevent such mishaps in future, there are still some loose ends.

In particular, donor sperm is occasionally imported from accredited foreign sperm banks for some couples undergoing fertility treatment here.

If a mix-up were to occur, it would be beyond the regulatory control and purview of the MOH in Singapore, and could develop into a complex legal tussle across international borders.

Additionally, although the MOH has regulations to ensure that imported sperm from a single donor does not give rise to more than three children in Singapore, there is no control over the number of children that the same donor can sire in the United States and other countries.

There have been reports of a sperm donor in the US siring up to 150 children, due to the lack of regulatory control. Experts warn that this could translate into an epidemic of accidental incest and the consequent spread of genetic diseases.

Commercial sperm banks worldwide have globalised their business in recent years, and they regularly export sperm from the same donor to many countries.

Given our modern era of increasing international travel and globalisation, children born of such sperm donors face increasing risks of accidental incest with their donor-conceived half-siblings worldwide.

There is a well-recognised phenomenon of "genetic sexual attraction", whereby close relatives such as siblings or half-siblings who first meet as adults become sexually attracted to each other.

Hence, MOH should reconsider its policy of importing donated sperm from abroad.

Currently, the import of frozen donor eggs is not permitted, and the status quo should remain.

Alexis Heng Boon Chin (Dr)