What do you know about the condition called Fragile X?

Question

I just heard of it. I understood the news reporter to say that there is a possible cure. Thanks!

Answer 1

Males only have one X chromosome and one Y chromosome.

Females have two X chromosomes.

This is what determines whether or not a baby will be male or female.

If there is a genetic problem on the X chromosome, it is much more likely to show up in the male, because he only has one copy. The female has an X from both parents, meaning that a defect in one may be overridden by the proper coding of the other x chromosome.

hence, the male's x chromosome is "fragile".

Answer 2

WIKI

Fragile X syndrome is a syndrome of X-linked mental retardation. Boys with the syndrome may have large testes (macroorchidism), prognathism, hypotonia and autism, and a characteristic but variable face with large ears, long face, high-arched palate, and malocclusion. Additional abnormalities may include lordosis, heart defect, pectus excavatum, flat feet, shortening of the tubular bones of the hands, and joint laxity. Females who have one fragile chromosome and one normal X chromosome may range from normal to mild manifestations of the fragile X syndrome. The fragile X syndrome has an estimated incidence of 1 in 3600 males and 1 in 4,000-6,000 females. [1]

Answer 3

I am not sure but I think it is a person who has a chromosome set up of XYX or XXY whichever is correct, this person is a male with an extra X chromosome with female traits such as wide hips and larger mammary glands. Or it could be a female with male traits such as a deep voice and facial hair.

Sorry, I was thinking of a different genetic disorder.

Answer 4

I know that Chris Benoit's son supposedly had it, and it leads to small stature and retardation. How can a genetic condition be cured?

Wikipedia Info:
Fragile X syndrome
Fragile X syndrome is a syndrome of X-linked mental retardation. Boys with the syndrome may have large testes (macroorchidism), prognathism, hypotonia and autism, and a characteristic but variable face with large ears, long face, high-arched palate, and malocclusion. Additional abnormalities may include lordosis, heart defect, pectus excavatum, flat feet, shortening of the tubular bones of the hands, and joint laxity. Females who have one fragile chromosome and one normal X chromosome may range from normal to mild manifestations of the fragile X syndrome. The fragile X syndrome has an estimated incidence of 1 in 3600 males and 1 in 4,000-6,000 females. [1]
Martin and Bell in 1943 described a pedigree of X-linked mental disability, without considering the macroorchidism.[2] In 1969 Herbert Lubs first sighted an unusual "marker X chromosome" in association with mental disability.[3] In 1970 Frederick Hecht coined the term "fragile site" (in Renpenning's syndrome is not synonymous with the Martin-Bell (fragile X) syndrome). In Renpennig's syndrome there is no fragile site on the X chromosome. Renpenning’s cases had short stature, moderate microcephaly, and neurological disorders.

Escalante's syndrome is synonymous with the fragile X syndrome. This term has been used in Brazil and other South American countries.

The fragile X syndrome is a genetic disorder caused by mutation of the FMR1 gene on the X chromosome. Mutation at that site is found in 1 out of about every 2000 males and 1 out of about every 259 females. (Incidence of the disease itself is about 1 in every 4000 females.)

Normally, the FMR1 gene contains between 6 and 55 repeats of the CGG codon (trinucleotide repeats). In people with the fragile X syndrome, the FMR1 allele has over 230 repeats of this codon.

Expansion of the CGG repeating codon to such a degree results in a methylation of that portion of the DNA, effectively silencing the expression of the FMR1 protein.

This methylation of the FMR1 locus in chromosome band Xq27.3 is believed to result in constriction of the X chromosome which appears 'fragile' under the microscope at that point, a phenomenon that gave the syndrome its name.

Mutation of the FMR1 gene leads to the transcriptional silencing of the fragile X-mental retardation protein, FMRP. In normal individuals, FMRP binds and facilitates the translation of a number of essential neuronal RNAs. In fragile X patients, however, these RNAs are not translated into proteins.

[edit] Transmission of the Fragile X

The diagram (right) of X-linked recessive inheritance is not entirely inappropriate but it markedly oversimplifies the situation and does not provide a sufficient foundation for genetic counseling about the fragile X syndrome. Technically, fragile X syndrome is an X-linked dominant condition with reduced penetrance.

Because males normally have only one copy of the X chromosome, those males with significant trinucleotide expansion at the FMR1 locus are symptomatic. They are intellectually disabled and may show various physical features of the fragile X syndrome.

Females have two X chromosomes and thus have double the chance of having a working FMR1 allele. Females carrying one X chromosome with an expanded FMR1 gene can have some signs and symptoms of the disorder or be normal. Although the extra X chromosome can serve as a backup, only one X chromosome is active at a time due to X-inactivation.

Males with the fragile X cannot transmit it to any of their sons (since males contribute a Y chromosome, not an X, to their male offspring), but will transmit it to all of their daughters, as males contribute their X to all of their daughters.

Females carrying one copy of the fragile X can transmit it to their sons or daughters; in this case each child has a 50% chance of inheriting the fragile X. Sons who receive the fragile X are at high risk of intellectual disability. Daughters who receive the fragile X may appear normal or they may be intellectually disabled, usually to a lesser degree than boys with the syndrome.

[edit] Symptoms
Prominent characteristics of the syndrome include an elongated face, large or protruding ears, and low muscle tone.
Prominent characteristics of the syndrome include an elongated face, large or protruding ears, and low muscle tone.

Aside from intellectual disability, prominent characteristics of the syndrome include an elongated face, large or protruding ears, flat feet, larger testicles in men (macroorchidism), and low muscle tone. Behavioral characteristics may include stereotypic movements (e.g., hand-flapping) and atypical social development, particularly shyness and limited eye contact. Some individuals with the fragile X syndrome also meet the diagnostic criteria for autism. Most females experience symptoms to a lesser degree because of their second X-chromosome, however they can develop just as severe symptoms. While full mutation males tend to present with severe intellectual disability, the symptoms of full mutation females runs the gamut of minimally affected to severe intellectual disability, which may explain why females are underdiagnosed relative to males.

[edit] Diagnosis

Fragile X syndrome was originally diagnosed by culturing cells in a folate deficient medium and then assessing the cultures for X-chromosome breakage by cytogenetic analysis of the long arm of the X chromosome. This technique proved unreliable for both diagnosis and carrier testing.


The fragile X abnormality is now directly determined by analysis of the number of CGG repeats and their methylation status using restriction endonuclease digestion and Southern blot analysis.

[edit] Treatment and current research

Recent studies have focused on a number of critical areas. The role of FMRP's RNA partners, many of which have now been validated through in vitro assays, is of primary importance. Also being examined is the function the various domains of FMRP, an RNA-binding protein, which is still relatively unknown.

While there is no current cure for the syndrome, there is hope that further understanding of its underlying causes would lead to new therapies. Currently, the syndrome can be treated through behavioral therapy, special education, medication, and when necessary, treatment of physical abnormalities. Persons with the fragile X syndrome in their family histories are advised to seek genetic counseling to assess the likelihood of having children who are affected, and how severe any impairments may be in affected descendants.

Answer 5

i read about it once in my genetics class...but that was many years ago.