Mumbai, Nov 14 (UNI) Fragile X syndrome is seen in one in 1,200 males and one in 2,500 females and it appears in families of every ethnic group and income level, according to Dr Manjeet Mehta, a Medical Geneticist.
Speaking to reporters yesterday, Dr Mehta said, ''Fragile-X is caused by an abnormality in the X chromosome, a copy of which is present in all individuals. Boys are usually more severely affected by the syndrome, as they have only one X chromosome. Girls have a second X chromosome, which can be used instead of the faulty one, and may have only mild disabilities. They may not exhibit any symptoms and may be carriers of the condition.'' Individuals with fragile X syndrome have normal growth and appearance. However, developmental milestones are typically delayed, particularly speech development. Between the toddler and preschool years certain behaviours may become noticeable, such as hyperactivity, short attention span, and autistic-like behaviours (difficulty adjusting to change, poor eye contact, hand biting or flapping, hypersensitivity to sound or light); also anxiety and mood swings.
''Affected males may have characteristic facial features such as a large head circumference, long face, prominent forehead, large ears, and prominent jaw. But these features are not always presented in young children with fragile X syndrome. Fragile X affects females in some different ways. About 16 to 19 per cent of females who are normal carriers experience premature ovarian failure (POF); meaning their ovarian function stops before normal menopause, sometimes well before the age of 40. Some may experience POF as early as their mid-twenties. POF affects a woman's ability to get pregnant,'' informed Dr Mehta.
A number of tests are used to diagnose Fragile X. Each test has its limitations, so in many cases more than one test may be used. The most common tests are Chromosome Studies. DNA studies being sensitive can also pick up carriers. The two main DNA tests include polymerase chain reaction (PCR) and Southern blot analysis. However, a comprehensive genetic evaluation (including routine Cytogenetic analysis) is critical since it can also pick up other chromosome abnormalities besides fragile X mutations in individuals referred with developmental delays.
''Care for fragile X syndrome consists of special education, occupational therapy, and speech therapy. One important factor in developing a child's long-term potential is early intervention. The sooner a child begins to get help, the more opportunity for learning. Because a young child's brain is still forming, early intervention gives children the best start possible and the best chance of developing their full potential. Even so, no matter when a person is diagnosed with Fragile X, it is never too late to benefit from treatment, '' said Dr Mehta.