FOR the first time, scientists are hot on the trail of a gene that shapes the
development of human language. The discovery may help explain why many speech
and language disorders arise.
快猫短视频s know that our genetic heritage can strongly affect our ability to
communicate. For example, identical twins tend to share linguistic ability or
disability.
Geneticists have tried to hunt down the genes that influence language
abilities by studying language disorders that can be inherited, such as
stuttering. But such disorders tend to have complex patterns of inheritance,
suggesting that many genes are involved, each making a small contribution. And
so far, they have not snared a single solid candidate.
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But now British researchers say they are close to identifying a gene they
call SPCH1. They report that after only six months of work, they have
narrowed their search to a small section of human chromosome 7 (Nature
Genetics,vol 18, p 168). 鈥淭his is a very good place to land,鈥� says
geneticist Anthony Monaco of the University of Oxford. 鈥淚t鈥檚 a well-mapped area,
so the rest of our work should go quickly.鈥�
The advance has only been possible because of an unusual family scientists
refer to as KE. Ten years ago, members of this family arrived at the Institute
of Child Health in London complaining that some of their relatives had a strange
speech affliction. 鈥淲hat strikes you first is that their speech is
unintelligible,鈥� says Faraneh Vargha-Khadem, a neuropsychologist at the
institute.
The afflicted relatives proved to have deficits in all aspects of speech, and
difficulty coordinating some facial muscles required for speech. Afflicted
children also had trouble mastering reading and writing. But what truly singled
out the KE disorder was the simple pattern of its inheritance. Genetic analysis
revealed that the condition was caused by a single, dominant mutation that could
be traced back to one of their grandmothers.
Vargha-Khadem and her colleagues collaborated with Monaco鈥檚 team to locate
the defective gene. They analysed different chromosome segments, reasoning that
afflicted individuals should share the grandmother鈥檚 version of the regions. Two
closely spaced segments of chromosome 7 showed a perfect match: they were
present in 15 linguistically impaired relatives, but absent in 12 healthy
ones.
This means that SPCH1 has to lie very close by, says Monaco. His
team also notes in research yet to be published that the same region on
chromosome 7 also plays a part in autism, another condition where language is
impaired. 鈥淭his suggests we are going to be helped a lot by knowing how this
gene works, and what role it plays in other disorders,鈥� says Vargha-Khadem.
鈥淚t鈥檚 exciting to think we鈥檙e going to start studying something as incredibly
sophisticated as language gene by gene,鈥� says Dennis Drayna of the National
Institute on Deafness and other Communication Disorders near Washington DC.
鈥淭his paper is a small step, but it has big implications.鈥�