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Related Concept Videos

Sex-linked Disorders

Sex-linked Disorders

Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in biological deficits, the disorder is considered sex-linked.

Autism Spectrum Disorder

Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition marked by persistent deficits in social communication and interaction alongside restrictive and repetitive behaviors or interests. ASD is sometimes accompanied by intellectual impairment.
These core symptoms manifest differently among individuals, ranging from mild to severe. The disorder's complexity extends beyond its clinical presentation, encompassing a diverse range of biological, cognitive, and sociocultural influences.

X-linked Traits

X-linked Traits

In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be masked by the presence of a normal allele on the second X. In contrast, a mutation on the X chromosome in males more often causes observable biological defects, as there is no normal X to compensate. Trait variations arising from mutations on the X chromosome are called “X-linked”.

X-linked Traits

X-linked Traits

Pedigree Analysis

Pedigree Analysis

Sex Linked Disorders

Sex Linked Disorders

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Related Experiment Video

Updated: Apr 18, 2026

A Robust Polymerase Chain Reaction-based Assay for Quantifying Cytosine-guanine-guanine Trinucleotide Repeats in Fragile X Mental Retardation-1 Gene

A Robust Polymerase Chain Reaction-based Assay for Quantifying Cytosine-guanine-guanine Trinucleotide Repeats in Fragile X Mental Retardation-1 Gene

Published on: September 16, 2019

Fragile X spectrum disorders.

Reymundo Lozano¹, Carolina Alba Rosero², Randi J Hagerman¹

¹UC Davis MIND Institute and Department of Pediatrics, UC Davis Medical Center, Sacramento, CA, USA;

Intractable & Rare Diseases Research

|January 22, 2015

Summary

This summary is machine-generated.

Fragile X Spectrum Disorder (FXSD) encompasses a range of conditions caused by FMR1 gene mutations. This review examines the phenotypes and genotypes of children affected by FXSD.

Keywords:

Fragile X syndrome autism spectrum disorder developmental delay intellectual disability premutation

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TMS: Using the Theta-Burst Protocol to Explore Mechanism of Plasticity in Individuals with Fragile X Syndrome and Autism

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Published on: December 28, 2010

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TMS: Using the Theta-Burst Protocol to Explore Mechanism of Plasticity in Individuals with Fragile X Syndrome and Autism

TMS: Using the Theta-Burst Protocol to Explore Mechanism of Plasticity in Individuals with Fragile X Syndrome and Autism

Published on: December 28, 2010

Area of Science:

Genetics
Neurodevelopmental Disorders
Molecular Biology

Background:

The FMR1 gene, located at Xp27.3, codes for FMRP and has normal alleles with 5-40 CGG repeats.
Abnormal alleles include gray zone (45-54), premutation (55-200), and full mutation (>200 CGG repeats).
FMR1 mutations are linked to Fragile X Syndrome (FXS), primary ovarian insufficiency (FXPOI), and tremor/ataxia syndrome (FXTAS).

Purpose of the Study:

To review the phenotypes and genotypes of children diagnosed with Fragile X Spectrum Disorder (FXSD).
To highlight the diverse range of conditions associated with FMR1 gene mutations.

Main Methods:

Literature review focusing on FMR1 gene mutations and associated clinical manifestations.
Analysis of genotypic variations (CGG repeat numbers) and phenotypic outcomes in affected individuals.

Main Results:

FMR1 mutations cause FXS, the leading genetic cause of intellectual disability and autism.
Premutations are associated with FXPOI, FXTAS, ADHD, ASD, anxiety, and depression.
FXSD is proposed to encompass the spectrum of FMR1-related disorders due to overlapping phenotypes.

Conclusions:

The term Fragile X Spectrum Disorder (FXSD) accurately reflects the wide range of phenotypes linked to FMR1 mutations.
Understanding the genotype-phenotype correlations in children with FXSD is crucial for diagnosis and management.