48,XXXY can result from meiotic or mitotic nondisjunction and is often considered a variant of Klinefelter syndrome (47,XXY), although boys with 48,XXXY often display a more complicated neurodevelopmental profile than boys with 47,XXY (Hayek et al., 1981; Gropman et al., 2010; Tartaglia et al., 2011). The estimated prevalence of this disorder is 1 in 50,000 live male births (Linden et al., 1995).
Boys with 48,XXXY may have global developmental delay in infancy. If left unaddressed, early speech delays may later manifest in language-based learning disorders, with expressive language slightly more impaired than receptive. Intellectual ability varies, with cognitive abilities falling between mildly retarded and within normal limits. These boys may be taller than average, with decreased testicular size, and limited forearm rotation. 48,XXXY boys’ personalities have been described as shy, sweet, passive, and nonassertive.
Developmental dyspraxia and other motor coordination difficulties can present in boys and girls with XY variations, yet the degree to which this persists in 48,XXXY warrants further investigation. Ongoing research has preliminarily found delayed independent ambulation, with later persistent difficulties in manual and motor coordination. Further research is warranted, however.
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.
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
Boys with 48,XXYY consistently exhibit Language-Based Learning Disabilities (LLD) and difficulties with 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 such visual-spatial activities as assembling 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…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
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
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.