PMC8850307_01
A couple gave birth to a Chimeric child with a partial trisomy 21 after IVF and EF. (A) Giemsa staining and analysis of the cultured peripheral blood mononuclear cells in the family members, in which the proband exhibits the combination of three karyotypes: 46,XX, add (21) (q22), 46,XX, dup (21) (q21.2q22.3) and 46,XX, der (21)del (21) (q22.1)t (21; 21) (q22.3; q22.1). (B) Copy number variation sequencing (CNV-seq) showed the copy number of Chr21 (q21.2-q22.3) was 2-3. The Trisomy 21 patient karyotype and CNV-seq results were used as positive control.
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F1
G-banding from peripheral blood cells of the patient showed a complicate karyotype of 46,XX,add (21) (q22)[25]/46,XX,der (21)del (21) (q22.1)t (21; 21) (q22.3; q22.1)[36]/46,XX,dup (21) (q22.1q22.3)[32] (Figure 1A). The CNV-seq result consistently showed the copy number of Chr21 from q22.1 to q22.3 was 2-3 (Figure 1B).
The stLFR whole-genome sequencing result showed multiple duplications and deletions in the proband's Chr21. (A) The mean depth distribution in different chromosomes of the proband. (B) Detailed copy number variations (CNVs) in the proband's Chr21 summarized from the genome sequencing comparison.
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F2
Figure 2 listed the candidate CNVs of Chr21, including multiple larger duplication and small deletion from q22.1 to q22.3.
Polymorphic Chr21 specific DNA marker analysis showed a paternal origin of the extra chromosome 21 fragment.
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F3
Tandem Repeat (STR) analysis with four Chr21-specific DNA markers was performed using the DNA extracted from the girl and parental blood samples. The result showed a paternal origin of the extra chromosome 21, indicating the paternal origin of the partial trisomy 21 (Figure 3).