Detection efficacy of non-invasive prenatal testing for copy number variations in the recurrent 17p12 region

doi:10.3969/j.issn.1674-8115.2025.03.007

Abstract

Abstract:

Objective ·To evaluate the detection efficacy and clinical value of non-invasive prenatal testing (NIPT) for identifying copy number variations (CNVs) in the recurrent 17p12 region, including the peripheral myelin protein 22 (PMP22) gene. Methods ·Pregnant women who underwent NIPT in the International Peace Maternity & Child Health Hospital, Shanghai Jiao Tong University School of Medicine between July 2020 and April 2024 were enrolled. Clinical data of individuals indicated as high-risk for microdeletions/duplications in the 17p12 region based on NIPT results were collected. Follow-up was conducted to assess the results of subsequent prenatal diagnosis and chromosomal microarray analysis (CMA) performed on peripheral blood from both the pregnant women and their husband. The positive predictive value (PPV) of NIPT for detecting microdeletions/duplications in the 17p12 region, as well as the underlying causes of false positives, was analyzed. Pregnancy outcomes and related clinical phenotypes of fetuses and pregnant women diagnosed with 17p12 CNVs were followed up. Results ·A total of 61 858 pregnant women underwent NIPT testing. NIPT identified 24 cases (0.04%) as high-risk for CNVs in the 17p12 region, including six cases of high-risk 17p12 microduplication and 18 cases of high-risk 17p12 microdeletion. All 24 pregnant women received genetic counseling, and 21 (87.50%) underwent invasive prenatal diagnosis. Invasive prenatal diagnostic confirmed four fetuses with 17p12 microduplications, nine fetuses with 17p12 microdeletions, and eight fetuses with no abnormalities, yielding a PPV of 61.90% (13/21). CMA analysis of maternal peripheral blood in the eight false-positive cases revealed that all mothers carried 17p12 CNVs. Further analysis of pregnant women with NIPT-indicated maternal CNVs revealed that all of them carried relevant CNVs. Among the 20 women with successful follow-up, the majority had normal deliveries, with only one case choosing to terminate the pregnancy due to a de-novo fetal 17p12 microduplication. Normally delivered fetuses (average age: 1.5 years) were followed up without reporting any significant abnormalities. Of the 16 pregnant women carrying 17p12 CNVs, only two exhibited clinical phenotypes associated with these CNVs, while the others remained asymptomatic. Conclusion ·NIPT demonstrates favorable detection efficacy for CNVs in the 17p12 region. Maternal CNVs are the primary cause of false-positive NIPT results for this region.

Key words: non-invasive prenatal testing (NIPT), 17p12 recurrent region, copy number variation (CNV), hereditary neuropathy with liability to pressure palsies (HNPP), Charcot-Marie-Tooth disease, type 1A (CMT1A)

CLC Number:

R714.55

ZHANG Lanlan, HAN Xu, LI Niu, WANG Jian, LI Shuyuan. Detection efficacy of non-invasive prenatal testing for copy number variations in the recurrent 17p12 region[J]. Journal of Shanghai Jiao Tong University (Medical Science), 2025, 45(3): 310-316.

Figures/Tables 3

TrendMD

References 25

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Item	dup(17p12) (n=6)	del(17p12) (n=18)	Total (n=24)
Maternal age/year	30.67±2.16	29.44±3.91	29.75±3.55
Gestational age/week	16.33±2.42	15.17±1.82	15.46±2.00
Fetal fraction/%	15.63±6.59	12.08±5.12	13.19±5.61
Unique reads/Mb	10.25±7.05	10.32±8.66	10.30±8.14

Item	dup(17p12) (n=6)	del(17p12) (n=18)	Total (n=24)
Maternal age/year	30.67±2.16	29.44±3.91	29.75±3.55
Gestational age/week	16.33±2.42	15.17±1.82	15.46±2.00
Fetal fraction/%	15.63±6.59	12.08±5.12	13.19±5.61
Unique reads/Mb	10.25±7.05	10.32±8.66	10.30±8.14

Case	NIPT	Maternal CMA	Prenatal CMA
1	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
2	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14196188‒15579519)×1	Not done
3	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14170219‒15599920)×1
4	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14170219‒15579519)×1
5	del(17p12, 1.30 Mb)-M	Not done	Not done
6	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14179738‒15581021)×1	arr[GRCh38]17p12(14179738‒15581021)×1
7	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14196248‒15579519)×1
8	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
9	del(17p12, 1.44 Mb)-M	Not done	arr[GRCh38]17p12(14195635‒15599920)×1
10	del(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
11	del(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14179738‒15581021)×1	arr[GRCh38]17p12(14195635‒15609739)×1
12	del(17p12, 1.57 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
13	del(17p12, 1.40 Mb)-M	arr[GRCh38]17p12(14184601_15579519)×1	Normal
14	dup(17p12, 1.40 Mb)-M	arr[GRCh38]17p12(14170219_15520772)×3	Normal
15	dup(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14333539‒15370528)×3	arr[GRCh38]17p12(14333539‒15370528)×3
16	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
17	del(17p12, 1.44 Mb)-M	Not done	arr[GRCh38]17p12(14179738‒15579519)×1
18	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14196248‒15579519)×1	arr[GRCh38]17p12(14179738‒15525587)×1
19	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14060292‒15484335)×1	arr[GRCh38]17p12(14060292‒15484335)×1
20	dup(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14073535‒15416912)×3	Normal
21	dup(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14170219‒15599920)×3	arr[GRCh38]17p12(14184601‒15520772)×3
22	dup(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14145268‒15533580)×3	arr[GRCh38]17p12(14184601‒15525587)×3
23	dup(17p12, 1.10 Mb)	Normal	arr[GRCh38]17p12(14182336‒15524164)×3
24	del(17p12, 1.31 Mb)	Not done	Not done

Case	NIPT	Maternal CMA	Prenatal CMA
1	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
2	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14196188‒15579519)×1	Not done
3	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14170219‒15599920)×1
4	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14170219‒15579519)×1
5	del(17p12, 1.30 Mb)-M	Not done	Not done
6	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14179738‒15581021)×1	arr[GRCh38]17p12(14179738‒15581021)×1
7	del(17p12, 1.30 Mb)-M	Not done	arr[GRCh38]17p12(14196248‒15579519)×1
8	del(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
9	del(17p12, 1.44 Mb)-M	Not done	arr[GRCh38]17p12(14195635‒15599920)×1
10	del(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
11	del(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14179738‒15581021)×1	arr[GRCh38]17p12(14195635‒15609739)×1
12	del(17p12, 1.57 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
13	del(17p12, 1.40 Mb)-M	arr[GRCh38]17p12(14184601_15579519)×1	Normal
14	dup(17p12, 1.40 Mb)-M	arr[GRCh38]17p12(14170219_15520772)×3	Normal
15	dup(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14333539‒15370528)×3	arr[GRCh38]17p12(14333539‒15370528)×3
16	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14166684‒15546686)×1	Normal
17	del(17p12, 1.44 Mb)-M	Not done	arr[GRCh38]17p12(14179738‒15579519)×1
18	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14196248‒15579519)×1	arr[GRCh38]17p12(14179738‒15525587)×1
19	del(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14060292‒15484335)×1	arr[GRCh38]17p12(14060292‒15484335)×1
20	dup(17p12, 1.30 Mb)-M	arr[GRCh38]17p12(14073535‒15416912)×3	Normal
21	dup(17p12, 1.44 Mb)-M	arr[GRCh38]17p12(14170219‒15599920)×3	arr[GRCh38]17p12(14184601‒15520772)×3
22	dup(17p12, 1.54 Mb)-M	arr[GRCh38]17p12(14145268‒15533580)×3	arr[GRCh38]17p12(14184601‒15525587)×3
23	dup(17p12, 1.10 Mb)	Normal	arr[GRCh38]17p12(14182336‒15524164)×3
24	del(17p12, 1.31 Mb)	Not done	Not done

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