A new case of pure partial 7q duplication

Area of Science:

• Genetics
• Developmental Biology
• Medical Diagnostics

Background:

• Chromosome 7q duplications are uncommon genetic alterations.
• Previous classifications of 7q duplications are based on broad chromosomal regions.
• Understanding the genetic basis of developmental disorders is crucial for diagnosis and treatment.

Observation:

• An 18-month-old boy conceived via assisted reproduction technology presented with developmental delay, hypotonia, microcephaly, frontal bossing, strabismus, malformed ears, and a short neck.
• Karyotype analysis revealed a de novo 18.69 Mb duplication at 7q21.1q22.3, identified using array comparative genomic hybridization (array-CGH).
• This duplication falls into group 3 of 7q duplications, characterized by interstitial duplications.

Findings:

• The patient's phenotype, while sharing some features with a previously reported case of a smaller duplication in the same region (psychomotor delay, hypotonia, frontal bossing, short neck, strabismus), exhibits distinct differences.
• The rarity of 7q duplications and limited detailed physical characterization in reported cases hinder robust phenotype-genotype correlations.
• Array-CGH analysis provides precise characterization of duplication size and location, essential for refining genetic disorder classifications.

Implications:

• This case highlights the importance of advanced molecular techniques like array-CGH in characterizing chromosomal abnormalities.
• Further research with detailed phenotyping and advanced molecular methods is needed to establish reliable phenotype-genotype correlations for partial 7q duplications.
• Improved classification of 7q duplications could lead to more accurate genetic counseling and potential therapeutic strategies for affected individuals.