Prenatal diagnosis of complete trisomy 16q in two consecutive pregnancies

Partial trisomy 16q and partial monosomy 7p of a fetus derivated from paternal balanced translocation: A case report

INTRODUCTION

Subchromosomal deletions and duplications could currently be detected by noninvasive preliminary screening (NIPS). However, NIPS is a screening test that requires further diagnosis. Here we report a fetus with an autosomal abnormality revealed by NIPS and conventional karyotype combined with copy number variations sequencing (CNV-seq) confirmed the fetus with an unbalanced translocation.

PATIENT CONCERN

This was the fourth pregnancy of a 30-year-old woman who underwent 2 spontaneous abortions and gave birth to a child with a normal phenotype. The woman and her husband were healthy and nonconsanguineous. NIPS indicated a repeat of about 19-Mb fragment at the region of 16q22.1-q22.4 at 17-week gestation.

DIAGNOSES

The combination of traditional karyotype and CNV-seq could better locate the abnormal chromosomal region and further identify the source of fetal chromosomal abnormalities. Simultaneously, we evaluated the fetal morphology by ultrasound examination. The karyotype of the fetus was 46,XX,der(7)t(7;16)(p22;q23) and CNV-seq results showed an approximately 20.96-Mb duplication in 16q22.1-q24.3 (69200001-90160000) and an approximately 3.86-Mb deletion in 7p22.3-p22.2 (40001-3900000). Prenatal ultrasound revealed the fetal micrognathia. The paternal karyotype was 46,XY, t (7;16) (p22;q23), while the maternal was normal. The fetus inherited an abnormal chromosome 7 from its father.

INTERVENTIONS

No treatment for the fetus.

OUTCOMES

Pregnancy was terminated.

CONCLUSIONS

To our knowledge, the occurrence of de novo partial trisomy 16q (16q22.1-qter) and partial monosomy 7p (7p22.2-pter) has not previously been reported up to now. Here, we present the perinatal findings of such a case and a review of the literatures. CNV-seq combined with karyotype is a useful tool for chromosomal abnormalities indicated by NIPS.

Karyotype/phenotype correlation in partial trisomies of the long arm of chromosome 16: case report and review of literature

Trisomy 16q is a clinically recognizable entity presenting with a wide spectrum of abnormalities. Only five infants with a diagnosis of partial trisomy 16q13 → qter have been previously reported, and all died during the first year of life. We report the clinical and molecular cytogenetic findings in a patient with trisomy 16q13 → qter due to the presence of a supernumerary marker chromosome (SMC). The child presented with microcephaly, ambiguous genitalia, cardiac malformations and dysmorphic features. Cytogenetic investigation using GTG-banding, spectral karyotyping (SKY) and fluorescence in situ hybridization analyses revealed an SMC of maternal origin with karyotype der(15)t(15;16)(q13;q13). Specific genotype-phenotype correlations among different segments of the 16q region cannot yet be defined. We suggest that the involvement of the entire region spanning from 16q11 to 16q22 is necessary for the characteristic phenotype of the trisomy 16q.

Novel duplication on chromosome 16 (q12.1-q21) associated with behavioral disorder, mild cognitive impairment, speech delay, and dysmorphic features: case report

We report on the 10-year follow-up and clinical, cytogenetic, and molecular investigation of a girl admitted for evaluation because of speech delay, learning difficulties, aggressive behavior, and dysmorphic facial features that included high forehead, round face, epicanthic folds, low-set dysplastic ears, flat nasal bridge, long flat philtrum, thin upper lip, small mouth, and short neck. The analysis of high-resolution GTG- and CTG-banding chromosomes suggested a de novo direct duplication of 16q12-q21 region and fluorescence in situ hybridization analysis with whole-chromosome specific 16 probe confirmed that the duplicated genetic material originated from the chromosome 16. Subsequently, array-based comparative genomic hybridization analysis with a ≈ 75 kb resolution showed a 9.92 Mb gain on the long arm of chromosome 16 at bands q12.1 through q21. To the best of our knowledge, this is the first case of duplication 16q12.1q21 described in literature. Several genes within the duplicated region are possibly correlated with clinical features present in our patient. Clinical and cytogenetic findings were compared with the small number of reported patients with pure duplications 16q, partially overlapping the one in our patient. Clinical phenotype seems to be distinctive between the proximal-intermediate and intermediate-distal regions of the long arm of the chromosome 16. In particular, we observed a set of dysmorphic features that could present a characteristic dup 16q11.2-q13 phenotype. The present study illustrates the advantages of an integrative approach using both conventional and molecular techniques for the precise characterization and genotype-phenotype correlation in patients with dysmorphism, behavioral problems, and learning difficulties.

Investigation of a patient with a partial trisomy 16q including the fat mass and obesity associated gene (FTO): fine mapping and FTO gene expression study

A female patient with a partial trisomy 16q was described previously. Her clinical characteristics included obesity, severe anisomastia, moderate to severe mental retardation, attention deficit hyperactivity disorder, dysmorphic facies, and contractions of the small joints. In this article, we describe a more detailed analysis of the genetic anomaly in this patient. We were particularly interested in the involvement of the fat mass and obesity associated gene (FTO) in her duplication. Single nucleotide polymorphisms in FTO have been associated with obesity. The breakpoints of the duplication were precisely mapped using high-resolution oligonucleotide array comparative genomic hybridization (CGH). We found that the duplication spans 11.45 Mb on 16q11.2 to 16q13 and it includes FTO. The increased copy number of FTO was confirmed with a qPCR on genomic DNA of the patient. We investigated the influence of the increased FTO copy number on FTO gene expression in immortalized lymphocytes from the patient using qPCR. No evidence of increased FTO expression was detected in the patient's lymphocytes. We discuss these findings and we review clinical findings in patients with overlapping 16q duplications to determine the relationship between increased FTO copy number and obesity. Our review suggests that duplication of the FTO gene does not necessarily result in obesity.

Fetal intra-abdominal calcifications from meconium peritonitis: sonographic predictors of postnatal surgery

OBJECTIVE

To study the relationship between prenatal ultrasound features and postnatal course of meconium peritonitis.

STUDY DESIGN

We reviewed our cohort of cases of meconium peritonitis (MP) (n = 13/37, 225 pregnancies or 0.3/1000) as well as those published in the English literature with prenatal ultrasonographic findings and postnatal follow-up (n = 56). The total number of cases (n = 69) was divided into 4 grades of progressive severity based on the number of pertinent sonographic findings: grade 0, isolated intra-abdominal calcifications (n = 18); grade 1, intra-abdominal calcifications and ascites (n = 17) or pseudocyst (n = 2) or bowel dilatation (n = 6); grade 2, two associated findings (n = 20); and grade 3, all sonographic features (n = 6). Presence of polyhydramnios was also recorded. Prenatal predictors of need for neonatal surgery and risk of neonatal death were identified using Chi-square and Fisher exact test, with P < 0.05 considered significant.

RESULTS

Neonatal surgical intervention was required in 0% (0/18) of newborns with grade 0 MP; in 52% (13/25) of those with grade 1; in 80% (16/20) with grade 2; and in 100% (6/6) with grade 3 MP (P < 0.001, Chi-square for trend). Moreover, neonatal surgery was more frequent in the presence than absence of polyhydramnios [69% (18/26) vs 37% (16/43); P = 0.007]. Neonatal mortality was 6% (4/69; 3 after surgery and 1 for premature delivery) and it was confined to the subgroup with polyhydramnios (4/26, 15%).

CONCLUSIONS

Prenatal sonographic features are related to postnatal outcome. Persistently isolated intra-abdominal calcifications have an excellent outcome. Delivery in a tertiary care center is recommended when calcifications are associated with other sonographic findings.