non-syndromic X-linked intellectual disability 21

Non-syndromic X-linked intellectual disability (NS-XLMR) 21, also known as MRX21, is a condition characterized by moderate to severe intellectual disability.

• Prevalence: The prevalence of NS-XLMR 21 is unknown.
• Inheritance: This condition is inherited in an X-linked recessive pattern, meaning it primarily affects males who have one affected X chromosome and one normal X chromosome. Females with one affected X chromosome and one normal X chromosome tend to have milder symptoms or may be asymptomatic.
• Symptoms: The primary symptom of NS-XLMR 21 is intellectual disability, which can range from moderate to severe. Individuals with this condition may also experience impaired speech and other developmental delays.

It's worth noting that the exact genetic cause of NS-XLMR 21 has not been identified in all cases, but it is associated with mutations in the X-chromosome. The identification of specific genes responsible for this condition continues to evolve as more research is conducted.

Sources: * [6] - This condition is classified under ORPHA:777. * [10] - NS-XLMR 21 is mentioned among other forms of non-syndromic X-linked intellectual disability. * [12] - Nonspecific X-linked intellectual deficiencies (MRX) belong to the family of sex-linked intellectual deficiencies (XLMR), which includes conditions like MRX21.

Understanding Nonspecific X-linked Intellectual Disabilities (MRX)

Nonspecific X-linked intellectual disabilities (MRX) are a group of genetic disorders characterized by intellectual disability as the primary symptom, without any associated physical, neurological, or psychiatric manifestations. This condition is distinct from syndromic or specific X-linked intellectual disabilities (MRXS), which present with additional symptoms and signs.

Causes and Genetics

Research has identified several genes responsible for MRX, including PHF8 [1], DLG3 [8], and others. The PHF8 gene plays a crucial role in regulating the activity of other genes by binding to chromatin complexes in brain cells before and after birth [2]. Mutations in these genes can lead to intellectual disability, highlighting the importance of genetic factors in MRX.

Characteristics and Features

MRX is characterized by intellectual disability without any additional symptoms or signs. In contrast, syndromic XLID patients display intellectual disability together with other developmental abnormalities [3]. The prevalence of MRX is unknown, but it is considered a rare condition [5].

Some individuals with MRX may exhibit specific physical features, such as bifid uvula, high palate, strabismus, or enuresis [6]. However, these features are not universal and may vary among affected individuals.

Inheritance and Age of Onset

MRX is inherited in an X-linked recessive pattern, meaning that the condition primarily affects males. The age of onset for MRX typically occurs during childhood or infancy [5].

References

• [1] Siderius et al. (2010) - PHF8 gene mutations cause X-linked intellectual disability, Siderius type.
• [2] PHF8 protein function and regulation in brain cells.
• [3] Kleine-Kohlbrecher et al. (2010) - Nonsyndromic XLID: a review of the literature.
• [5] Prevalence and inheritance pattern of MRX.
• [6] Clinical features associated with MRX.

Note: The above response is based on the provided context, which includes search results containing brief descriptions of web page content. The answer is generated without repeating any text from the original sources and provides a concise summary of the key points

Based on the provided context, it appears that diagnostic tests for non-syndromic X-linked intellectual disability have evolved over time.

Current Diagnostic Recommendations

According to search result [5], medical genetics groups now recommend chromosomal microarray analysis (CMA) as a first-line genetic test to identify genetic mutations in children with intellectual disabilities. This suggests that CMA is a widely accepted and recommended diagnostic approach for non-syndromic X-linked intellectual disability.

Other Diagnostic Tests

While CMA is the recommended first-line test, other diagnostic tests may also be considered depending on the individual case. For example, search result [4] mentions that genetic testing can help diagnose the specific type of intellectual disability present and guide treatment. This implies that a range of genetic tests may be used to identify underlying causes of non-syndromic X-linked intellectual disability.

Laboratories and Resources

Search results [3] and [14] provide information on laboratories and resources available for diagnostic testing, including clinical trials and patient registries. These resources can be useful for individuals seeking diagnostic testing or treatment options.

In summary, the current diagnostic approach for non-syndromic X-linked intellectual disability involves chromosomal microarray analysis (CMA) as a first-line test, with other genetic tests and resources available depending on individual cases.

References:

[5] Medical genetics groups recommend chromosomal microarray analysis (CMA) as a first-line genetic test. [4] Genetic testing can help diagnose the specific type of intellectual disability present and guide treatment. [3] Laboratories provide diagnostic tests and research opportunities. [14] This panel of 114 genes is intended for patients with a diagnosis or clinical suspicion of X-Linked Intellectual Disability (XLID).

Current Status of Drug Treatment for Non-Syndromic X-Linked Intellectual Disability

Unfortunately, there is no specific pharmacologic treatment available for cognitive impairment in individuals with non-syndromic X-linked intellectual disability (NS-XLID) [8]. However, research continues to explore potential therapeutic options.

• General Principles: When considering antiepileptic drug treatment, the selection of the drug should be based on the underlying cause and severity of the condition [11].
• Gene-Specific Therapies: While there are no specific drugs available for NS-XLID, researchers have identified several genes associated with this condition. Further studies are needed to explore potential gene-specific therapies.
• Emerging Treatments: Recent research has highlighted the importance of transcription process, mitochondrial function, glycoprotein metabolism, and ubiquitination in X-linked intellectual disability [15]. These findings may lead to the development of novel therapeutic approaches.

It is essential to consult with a healthcare professional for medical advice and treatment. They can provide personalized guidance based on individual circumstances.

References: [8] Nov 16, 2021 — No specific pharmacologic treatment is available for cognitive impairment in the developing child or adult with intellectual disability (ID). [11] Kaufman L., Ayub M., Vincent J.B. The Genetic Basis of Non-Syndromic Intellectual Disability: A Review. J. Neurodev. ... [15] Genes that are involved in the transcription process, mitochondrial function, glycoprotein metabolism, and ubiquitination dominate the list of 21 new genes associated with X-linked intellectual disability since the last update in 2017.

Differential Diagnoses for Non-Syndromic X-Linked Intellectual Disability

Non-syndromic X-linked intellectual disability (NS-XLID) is a complex neurodevelopmental disorder that can be challenging to diagnose. The differential diagnosis for NS-XLID includes various conditions that present with similar symptoms or clinical findings.

Other Forms of X-Linked ID

• Other forms of X-linked intellectual disability should be considered in the differential diagnosis, as they may present with similar symptoms.
• These include other genes and syndromes that are associated with intellectual disability, such as Fragile X syndrome, which is caused by mutations in the FMR1 gene. [8][10]
• The prevalence of each non-syndromic gene is estimated to be around 1-2% in selected research samples where at least two males are affected. [11]

Differential Diagnosis Options

• Differential diagnosis options for NS-XLID include:
  • Börjeson-Forssman-Lehmann syndrome
  • Wilson-Turner syndrome
  • Smith-Fineman-Myers syndrome
  • Other X-linked intellectual disability syndromes that involve similar symptoms or clinical findings. [7][9]
• All genes known to be associated with intellectual disability should be included in the differential diagnosis of individuals with NSID, including those with isolated ID or ID with additional clinical features. [12]

Prevalence and Genetic Factors

• Intellectual disability affects 1-3% of the Western population and is heterogeneous in origin.
• Mutations in X-linked genes represent 5-10% of ID in males, while Fragile X syndrome is the most common form of ID, with a prevalence of around 1:5000 males. [13]
• Females are usually non- or mildly affected due to the presence of two X chromosomes, which can compensate for the mutation. [13]

Genetic Panel and Screening

• An intellectual disability multigene panel that includes TRIO and other genes should be considered in the differential diagnosis.
• Systematic screening of all other X-linked genes in X-linked families with mental retardation is currently not feasible in a clinical setting, but may be considered on a case-by-case basis. [15]