Non-mosaic partial duplication 12p in a patient with dysmorphic characteristics and developmental delay

Area of Science:

• Genetics
• Human Biology
• Medical Genetics

Background:

• Duplication of chromosome 12 short arm (12p) is a rare chromosomal abnormality.
• It can arise de novo or from parental translocation segregation.
• Phenotype typically includes dysmorphic features, congenital anomalies, and intellectual disability.

Purpose of the Study:

• To provide a clinical description and cytogenetic analysis of a patient with non-mosaic partial duplication and paracentric inversion of 12p.
• To perform genotype-phenotype correlation in this rare condition.
• To contribute to the understanding of "pure" partial duplication 12p.

Main Methods:

• Clinical description and cytogenetic analysis.
• Cytogenomic analysis to detect genetic gain.
• GTG-banding karyotyping and chromosomal region analysis.

Main Results:

• A patient presented with facial dysmorphism, developmental delay, and intellectual impairment.
• A de novo non-mosaic partial duplication of 12p (approx. 28 Mb) and a paracentric inversion were identified.
• Karyotype: 46,XX,invdup(12)(pter → p13.32::p11.1 → p13.31::p13.31 → qter).
• Region of genetic gain: arr[GRCh37]12p13.31-p11.1(6914072_34756209)x3.

Conclusions:

• The identified chromosomal alteration is a "pure" partial duplication 12p.
• This case expands genotype-phenotype correlation data for partial duplication 12p.
• Highlights the role of genes within duplicated regions in neurodevelopmental outcomes.