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Published on: October 20, 2019
Recurrent Male Hydrops Fetalis Reveals Hidden Incontinentia Pigmenti: Lessons From Pseudogene-Interfered Genomic
Chunge Cao1, Yao Zhang2, Yingjun Yang1
1Department of Obstetrics, Center of Fetal Medicine & Intrauterine Pediatrics, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Objective:
To report incontinentia pigmenti (IP) as an overlooked genetic etiology in three families with recurrent non-immune hydrops fetalis (NIHF), and to highlight the necessity of phenotype-driven targeted prenatal testing and multidisciplinary care in the next-generation sequencing (NGS) era.
Methods:
Three unrelated families with recurrent male NIHF and negative chromosomal microarray analysis/NGS results were investigated. Genetic counselors conducted detailed maternal history-taking and physical examinations to identify subtle ectodermal features suggestive of IP. Targeted long-range PCR and multiplex ligation-dependent probe amplification (MLPA) were employed to bypass interference from the pseudogene IKBKGP1 and detect IKBKG exon 4-10 deletions.
Results:
All three mothers displayed subtle ectodermal features, including hypopigmented streaks, patchy alopecia, and dental anomalies. Genetic testing revealed heterozygous IKBKG exon 4-10 deletions in all 3 mothers, and a hemizygous deletion in the third affected male fetus of Family 3-both missed by conventional short-read NGS. Prenatal ultrasound consistently demonstrated increased nuchal translucency, cervical cystic hygroma, and generalized edema, serving as early indicators of IP-related NIHF.
Conclusion:
Pseudogene-aware molecular tools combined with maternal phenotyping are essential for uncovering hidden IP and reducing unexplained fetal loss in the NGS era.
