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Chromosomal Array CGH - BLOOD

Blood
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Report in 168Hrs

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At Home

nofastingrequire

No Fasting Required

Details

Detects chromosomal imbalances (deletions/duplications).

₹21,460₹30,657

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Chromosomal Array CGH - BLOOD

  • Why is it done?
    • Detects chromosomal imbalances including deletions, duplications, and copy number variations (CNVs) across the entire genome using array-based comparative genomic hybridization (aCGH) technology from a blood sample
    • Diagnostic evaluation of developmental delay, intellectual disability, and autism spectrum disorder in children
    • Investigation of congenital malformations and multiple birth defects of unknown etiology
    • Evaluation of growth abnormalities and failure to thrive
    • Assessment of recurrent pregnancy loss and infertility in patients with suspected chromosomal abnormalities
    • Identification of submicroscopic chromosomal abnormalities not detectable by conventional cytogenetics (karyotyping)
    • Evaluation of patients with suspected genetic syndromes and dysmorphic features
    • Cancer predisposition screening in patients with family history of malignancies
  • Normal Range
    • Normal Result: No copy number variations (CNVs) detected; balanced genome with two copies of each chromosome region (diploid state); reported as '46,XX' or '46,XY' equivalent in array format with no pathogenic variants identified
    • Measurement Unit: Log2 ratio values typically ranging from -1.0 to +1.0 for normal diploid regions; deletions show negative values (approaching -1.0 for monosomy); duplications show positive values (approaching +1.0 for trisomy)
    • Abnormal Result: Detection of submicroscopic deletions or duplications ≥50 kilobases (kb) in size; classified as pathogenic, likely pathogenic, variants of uncertain significance (VUS), likely benign, or benign based on clinical significance
    • Benign Variants: Common CNVs or copy number neutral variants with no known clinical significance; may be flagged separately from pathogenic findings
    • Interpretation Context: Results interpreted based on clinical phenotype, family history, inheritance pattern, and comparison to reference databases (ClinVar, DGV, DECIPHER, ISCA)
  • Interpretation
    • Pathogenic Deletions: Loss of genetic material causing haploinsufficiency; associated with developmental delay, intellectual disability, facial dysmorphism, congenital malformations; examples include 22q11.2 deletion syndrome, Wolf-Hirschhorn syndrome, Prader-Willi syndrome
    • Pathogenic Duplications: Excess genetic material causing gene dosage imbalance; may result in developmental disorders, autism spectrum features, intellectual disability; includes duplications of Xp11.22 associated with intellectual disability and autism
    • Likely Pathogenic Variants: CNVs with strong evidence of causative relationship to clinical phenotype but not definitively proven; recommend confirmatory testing and genetic counseling
    • Variants of Uncertain Significance (VUS): CNVs with unclear clinical significance; may require additional testing, functional studies, or family segregation analysis to determine pathogenicity; may be reclassified as new evidence emerges
    • Likely Benign Variants: CNVs with minimal evidence of clinical significance; likely inherited polymorphisms; generally not associated with phenotypic abnormalities
    • Benign Variants: Common population CNVs with no known pathogenic effect; typically inherited from unaffected parent; no clinical intervention required
    • Factors Affecting Interpretation: Clinical phenotype correlation; family history and inheritance pattern; parental testing results; population frequency of variant; presence of gene dosage sensitivity; mosaic status affecting cell-to-cell variation
    • De Novo Variants: Newly arising CNVs not present in either parent; generally more likely to be pathogenic; higher risk of recurrence in future pregnancies if germline mosaicism present
    • Size Considerations: Larger deletions or duplications (>5 megabases) typically associated with more severe phenotypes and multiple genes affected; smaller CNVs may have subtle effects
  • Associated Organs
    • Primary Systems Affected:
    • Central Nervous System: Developmental delay, intellectual disability, hypotonia, seizures, autism spectrum disorder, ADHD, cerebral palsy, brain malformations
    • Cardiovascular System: Congenital heart defects, septal abnormalities, valvular defects, coarctation of aorta, tetralogy of Fallot (associated with 22q11.2 deletions)
    • Skeletal System: Growth retardation, bone abnormalities, limb malformations, vertebral anomalies, microcephaly
    • Craniofacial Features: Dysmorphic facial features, cleft palate, ear malformations, hypertelorism, micrognathia, short stature
    • Gastrointestinal System: Esophageal atresia, tracheoesophageal fistula, anal malformations, feeding difficulties
    • Genitourinary System: Kidney abnormalities, urinary tract malformations, genital anomalies, hypospadias
    • Associated Genetic Syndromes:
    • DiGeorge Syndrome (22q11.2 deletion): Cardiac defects, thymic hypoplasia, facial dysmorphism, cleft palate, immunodeficiency
    • Williams-Beuren Syndrome (7q11.23 deletion): Supravalvular aortic stenosis, facial features, intellectual disability, hypercalcemia
    • Prader-Willi Syndrome (15q11-q13 deletion): Infantile hypotonia, failure to thrive, obesity, hypogonadism, intellectual disability
    • Angelman Syndrome (15q11-q13 maternal deletion): Developmental delay, seizures, ataxia, characteristic facial features, happy demeanor
    • Wolf-Hirschhorn Syndrome (4p deletion): Severe developmental delay, distinctive 'Greek warrior helmet' facial features, growth retardation, seizures
    • Cancer Predisposition:
    • Deletions or duplications involving tumor suppressor genes (TP53, BRCA1, BRCA2) or oncogenes may predispose to hereditary cancer syndromes; increased risk of various malignancies depending on specific genes involved
  • Follow-up Tests
    • Confirmatory Testing:
    • Fluorescence in situ hybridization (FISH): Confirmatory testing for specific chromosomal regions detected on array; validates pathogenic findings
    • Quantitative PCR (qPCR): High-resolution copy number confirmation; useful for targeted verification of CNVs at breakpoint regions
    • Karyotyping: Conventional cytogenetics to evaluate for large chromosomal abnormalities; recommended if array results show unusual patterns
    • Parental Testing:
    • Parental chromosomal array or targeted FISH: Determines inheritance pattern (de novo vs inherited); identifies carrier status in parents; critical for genetic counseling and recurrence risk
    • Complementary Genetic Testing:
    • Whole exome sequencing (WES): Identify point mutations and small indels; useful when array results are negative or VUS requires further investigation
    • Whole genome sequencing (WGS): Comprehensive genetic analysis including intronic and regulatory regions; highest diagnostic yield for unsolved cases
    • Targeted gene testing: Sequencing of specific genes associated with detected CNV region to identify causative mutations
    • Methylation Studies:
    • DNA methylation analysis: Indicated for suspected imprinting disorders (Prader-Willi, Angelman syndromes); evaluates epigenetic abnormalities not detected by standard array
    • Clinical Monitoring and Assessment:
    • Developmental assessment: Psychometric testing, cognitive evaluation to characterize intellectual disability; repeat at intervals to monitor progress
    • Imaging studies: Brain MRI/ultrasound for CNS abnormalities; cardiac imaging (echocardiography) for cardiac defects; renal ultrasound for urinary tract abnormalities
    • Audiology testing: Hearing assessment for congenital hearing loss associated with certain CNVs; early identification important for language development
    • Ophthalmologic examination: Vision screening and assessment for visual impairments
    • Speech and language evaluation: Assessment of communication abilities; therapeutic intervention if needed
    • Specialized Testing Based on Phenotype:
    • Immunological evaluation: T-cell counts, immune function testing for suspected immunodeficiency (DiGeorge syndrome)
    • Endocrinologic assessment: Growth hormone testing, thyroid function; monitoring for metabolic abnormalities
    • Calcium metabolism studies: Serum calcium, phosphate levels for syndromes with hypercalcemia risk
    • Genetic Counseling:
    • Genetic counselor consultation: Essential for interpretation, family implications, inheritance patterns, recurrence risks, reproductive options; prenatal testing discussion for future pregnancies
  • Fasting Required?
    • Fasting Required: No
    • Chromosomal array CGH analysis does not require fasting; test can be performed at any time of day
    • Sample Collection Requirements:
    • Peripheral blood sample collection via venipuncture into sterile EDTA (ethylenediaminetetraacetic acid) tube, also known as lavender-top or purple-top tube
    • Typical volume: 3-5 mL of whole blood; ensure adequate fill of collection tube to maintain proper EDTA ratio
    • Gentle mixing of sample after collection by inverting tube 8-10 times; do not shake vigorously to prevent hemolysis
    • Storage and Handling:
    • Keep blood sample at room temperature (15-25°C); do not refrigerate or freeze whole blood as it may compromise DNA quality
    • Send sample to laboratory within 24-48 hours of collection; check specific laboratory instructions for optimal timing
    • Ensure sample is properly labeled with patient identification, date, and time of collection
    • Patient Preparation:
    • No fasting required; patient can eat and drink normally before blood draw
    • No specific medication restrictions; medications do not affect array CGH results
    • Physical activity: Normal activity level maintained; no specific restrictions on exercise prior to collection
    • Stress and hydration: Maintain normal hydration; state of hydration does not significantly affect DNA quantity or quality in blood sample
    • Special Considerations:
    • Contamination prevention: Avoid external contamination of collection tube exterior; use aseptic technique during venipuncture
    • Hemolysis avoidance: Difficult draws or excessive force during venipuncture can cause hemolysis; avoid if possible as this may affect test quality
    • Newborns and young children: Can be tested at any age; neonatal dried blood spots may be used if available, though fresh blood sample preferred

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