Myths about 48,XXYY (and why they are just myths!)
Boys with 48,XXYY consistently present with Language-Based Learning Disabilities (LLD) and Motor Planning Issues that are related to the high rate of dyslexia associated with the disorder
However, they seem to be stronger in math and visual-spatial activities such as puzzles or remembering directions
Intellectual disabilities are common in 48,XXYY, with average full-scale IQs in the range of 70-80
Verbal IQs are seen to be significantly lower than performance IQs, due to language-based learning difficulties
Boys with 48,XXYY may have low testosterone, which can affect development and fertility
Several studies and case reports have shown that the use of testosterone therapy can improve behavior and other symptoms for boys with 48,XXYY in a safe manner
XXYY affects as many as 1 in 18,000 boys.
X & Y Chromosomal Variations are commonly misdiagnosed as only being speech or motor delays, leaving many affected children undiagnosed
ADHD is commonly seen in boys with XXYY, as well as Autism Spectrum Disorder to a lesser extent
Adults with XXYY are typical tall in stature, with estimates of average height between 6’0” and 6’4”
Boys with XXYY usually develop a tremor during adolescence which typically worsens as they age
Dental problems are common with XXYY, with delays in the development of “baby” and “adult” teeth as well as thin enamel, cavities, and misaligned teeth
As many as 1 in 18,000 boys are affected by 48, XXYY. They consistently present with Language-Based Learning Disabilities (LLD) and Motor Planning issues that are related to the high rate of dyslexia associated with the disorder. However, they seem to be stronger in math and visual-spatial activities, such as assembling puzzles or remembering directions. ADHD is commonly seen in boys with XXYY, as well as Autism Spectrum Disorder, to a lesser extent.
Boys with 48, XXYY may have low testosterone, which can affect development and fertility. Several studies and case reports have shown that the use of testosterone therapy in a safe manner can improve behavior and other symptoms for boys with 48, XXYY.
48, XXYY boys usually develop a tremor during adolescence which typically worsens as they age. Dental problems are common, with delays in the development of “baby” and “adult” teeth, as well as issues with thin enamel, cavities, and misaligned teeth. Adults with 48, XXYY are typically tall in stature, with estimates of average height between 6’0” and 6’4”.
Intellectual disabilities are common in 48, XXYY, with average full-scale IQs in the range of 70-80.
Verbal IQs are seen to be significantly lower than performance IQs, due to language-based learning difficulties.
Related X & Y Disorder Research
X&Y Variation Disorders encompass individuals who are born with 45, 47, 48, or 49 chromosomes, rather than the standard 46. The Focus Foundation’s efforts are centered on disorders resulting from having 47, 48, and 49 chromosomes. 45, X (also known as Turner’s Syndrome) occurs in one out of 2,000 live female births and is actively and effectively served by The Turner Syndrome Society. Below are more details about X&Y Variations involving 47, 48, and 49 chromosomes:
Only 25% of males with 47,XXY are ever diagnosed during their lifetimes; fewer than 10% of 47,XXY individuals are identified prior to adolescence. This means that millions of affected children remain undiagnosed–often because they are commonly misdiagnosed as simply having speech or motor delays. More than 500,000 people are believed to have 47,XXY disorders in the United States alone, with an equal distribution across all racial and socio-economic groups.
Based on scientific studies, it is important to consider early hormonal replacement therapy (EHRT) for 47,XXY boys (who experience decreased testosterone production during three critical developmental periods) before they are 18 months old. Testosterone treatment given then has been shown to have a positive impact on brain function through 9 years of age…READ MORE
At least 85% of those with 47,XYY are never diagnosed. 47,XYY boys consistently present with language-based Learning Disabilities and difficulties with Motor Planning–both issues that are related to the high rate of dyspraxia and dyslexia associated with the disorder. However, 47,XYY boys are commonly misdiagnosed as simply having speech or motor delays.
Boys with 47,XYY typically reach an average height of between 6’3” and 6’5”…READ MORE
As many as 1 in 900 girls have 47,XXX. Unfortunately, millions of affected girls are undiagnosed. Girls who are prenatally diagnosed and receive early intervention services typically exhibit fewer and less severe cognitive disabilities.
There is an equal distribution of 47,XXX across all racial and socio-economic groups…READ MORE
48,XXXX (also known as Tetrasomy X or Tetra X) is a rare sex chromosome disorder that was first identified in the early 1960s. Since that time, approximately 100 cases have been reported, although less than 50 are described in scientific literature. Due to the scarcity of this female chromosomal variation, it is difficult to define a common phenotypic presentation. A lack of congenital malformations, mild dysmorphology, and varied developmental trajectory suggests that 48,XXXX is largely underdiagnosed…READ MORE
48,XXXY can result from meiotic or mitotic nondisjunction (errors in chromosomal separation) and is often considered a variant of Klinefelter syndrome (47,XXY). However, boys with 48,XXXY often exhibit a more complicated neurodevelopmental profile than boys with 47,XXY…READ MORE
The first case of 49,XXXXY syndrome was reported in the 1970s, and this chromosomal variation remains one of the rarest sex chromosome disorders. 49,XXXXY results from nondisjunction (errors in chromosomal separation) of the X chromosome occurring during both Meiosis I and Meiosis II…READ MORE
Penta X Syndrome is an extremely rare chromosomal disorder that only affects females. While girls normally only have two X chromosomes, girls with Penta X have five X chromosomes. As of 2011, less than 40 cases have been reported.…READ MORE
Klinefelter Syndrome & Other Names You May hear
X & Y Variations is a neurogenetic disorder known by many names, among them: Sex Chromosome Disorders, X & Y Chromosomal Variations, Sex Chromosome Anomaly and Sex Chromosome Aneuploidy Variations. Within the disorder are many sub-categories, which are identified by names including 47 XXY (Klinefelter Syndrome), 49 XXXXY, Tetrasomy X, 49 XXXXXX, Pentasomy X, 48 XXY.
What You Can Do Now
If you have received a prenatal diagnosis indicating that your child has an X & Y chromosomal variation, or feel that your son or daughter is experiencing developmental delays or developmental dysfunction, the following options are designed to help you take the next step in securing appropriate treatment or an early diagnosis.