What are the other Names for this Condition? (Also known as/Synonyms)

• Chromosome X Disorders

What are Disorders of Chromosome X? (Definition/Background Information)

There are many disorders that are caused by abnormalities on chromosomes X. Some are more common than others. Researchers know more about certain chromosomal disorders than others. Information is constantly being added through research, better documentation, and increased awareness.

Chromosomes are microscopic protein structures present in each cell nucleus that carry genetic information in the form of DNA (deoxyribonucleic acid). Humans have 46 chromosomes in the cell nucleus, in 23 pairs, of which one pair is named the sex chromosome. In males, it is designated XY, for chromosome X and chromosome Y; while, in females, it is designated XX, for a pair of chromosome X. The other 22 pairs of chromosomes are numbered chromosome 1 through 22.

During conception, the embryo inherits one copy of each chromosome from each parent (i.e., mother and father). Any alteration in the chromosome numbers or structure can result in mild to severe genetic abnormalities. Specialized genetic testing techniques are often required to confirm the diagnosis.

Chromosome X Disorders are disorders involving chromosome X. Some of the disorders include:

DDX3X Syndrome: DDX3X Syndrome is a genetic disorder caused by mutations in the DDX3X gene on the X chromosome. It predominantly affects females and can lead to a variety of developmental and neurological challenges. While congenital heart defects are not a defining feature of this syndrome, they can occur in some individuals. Common symptoms may include intellectual disability, developmental delays, language impairments, behavioral issues, and distinct facial features. Treatment focuses on managing the specific symptoms and providing supportive care to address developmental, educational, and medical needs.

Norrie Disease: Norrie Disease is a rare genetic disorder that primarily affects males and is caused by mutations in the NDP gene on the X chromosome. It is characterized by congenital blindness, progressive hearing loss, and developmental delays. While eye abnormalities are a hallmark of Norrie Disease, congenital heart defects are not commonly associated with this condition. Treatment involves managing the specific symptoms, providing supportive care for visual and hearing impairments, and addressing developmental needs.

Trisomy X Syndrome: Trisomy X Syndrome, also known as 47,XXX syndrome, is a chromosomal disorder in females characterized by the presence of an extra X chromosome. While congenital heart defects are not a defining feature of this syndrome, they can occur in some cases. Common signs and symptoms may include tall stature, learning difficulties, delayed speech and language skills, and mild developmental delays. Treatment involves addressing the specific needs of the individual, including educational support, speech and language therapy, and addressing any medical or developmental concerns.

Chromosome Xq Duplication Syndrome: Chromosome Xq Duplication Syndrome refers to a genetic disorder characterized by the duplication of genetic material on the long arm of the X chromosome. It can lead to a variety of physical and developmental challenges, but the specific association with congenital heart defects is unclear. Common symptoms may include intellectual disability, developmental delays, distinctive facial features, and other physical abnormalities. Treatment involves managing the specific symptoms and providing supportive care tailored to the individual's needs.

46,XX Gonadal Sex Reversal Syndrome: 46,XX Gonadal Sex Reversal Syndrome, also known as Swyer syndrome, is a rare genetic disorder in individuals with female chromosomes (XX) but with undifferentiated or male gonads. It is caused by mutations in genes involved in gonadal development. While not a direct association, some individuals with this syndrome may have structural abnormalities of the heart. Common symptoms may include primary amenorrhea (absence of menstruation), underdeveloped female secondary sexual characteristics, and infertility. Treatment usually involves hormone replacement therapy and may include surgical interventions to address fertility or associated anatomical abnormalities.

49,XXXXX Syndrome: 49,XXXXX Syndrome, also known as Pentasomy X or XXXXX Syndrome, is a chromosomal disorder in females characterized by the presence of an extra X chromosome. This condition is associated with various health issues, but the specific association with congenital heart defects is unclear. Common symptoms may include intellectual disability, developmental delays, distinctive facial features, growth abnormalities, and other physical and neurological challenges. Treatment focuses on managing the specific symptoms and providing supportive care tailored to the individual's needs.

46,XX Gonadal Dysgenesis Epibulbar Dermoid Syndrome: 46,XX Gonadal Dysgenesis Epibulbar Dermoid Syndrome, also known as XXGD-ED Syndrome, is a rare genetic disorder characterized by gonadal dysgenesis (underdeveloped or absent ovaries) in individuals with female chromosomes (XX) and the presence of an epibulbar dermoid, a type of eye tumor. While congenital heart defects are not typically associated with this syndrome, individuals with XXGD-ED Syndrome may still have an increased risk of heart abnormalities. Treatment involves addressing the specific symptoms and providing supportive care tailored to the individual's needs, which may include hormone replacement therapy and surgical interventions for the eye tumor if necessary.

This article is a resource with links to other more specific disorders. Information on each Chromosome X Disorder may be viewed by clicking on the respective subtypes (above).

Information to join DoveMed’s patient forum called MyCIrcles to learn and manage the condition is also included. We are adding more information to this page periodically. Please bookmark this page for future reference and visit for updated content.

You can join Chromosome Disorders MyCircles patient forum by visiting here: https://www.dovemed.com/mycircles/circles/all