Prenatal diagnosis and molecular cytogenetic characterization of a de novo unbalanced reciprocal translocation of der(9)t(9;14)(p24.2;q32.11) associated with 9p terminal deletion and 14q distal duplication

Using a new analytic approach for genotyping and phenotyping chromosome 9p deletion syndrome

Using a new analytic method ("unique non-overlapping region" (UNOR) analysis), we characterized the genotypes and phenotypes of a large cohort of individuals diagnosed with chromosome 9p deletion syndrome (9PMS) and defined critical genomic regions. We extracted phenotypic information from 48 individuals with 9PMS from medical records and used a guided interview with caregivers to clarify ambiguities. Using high-resolution whole-genome sequencing for breakpoint definition, we aligned deletions and drew virtual breakpoints to obtain UNORs associated with phenotypic characteristics. We next extracted genotype and phenotype data for 57 individuals identified from a systematic review of the 9PMS literature and analyzed these as above. Common phenotypic features included developmental delay/intellectual disability, dysmorphic features, hypotonia, genital defects in XY individuals, psychiatric diagnoses, chronic constipation, atopic disease, vision problems, autism spectrum disorder, gastroesophageal reflux disease, trigonocephaly, congenital heart disease, and neonatal hypoglycemia. Our approach confirmed previous literature reports of an association of FREM1 with trigonocephaly and suggested a possible modifier element for this phenotype. In conclusion, the UNOR approach delineated phenotypic characteristics for 9PMS and confirmed the critical role of FREM1 and a possible long-distance regulatory element in pathogenesis of trigonocephaly that will need to be replicated in future studies.

A Recurrent De Novo Terminal Duplication of 14q32 in Korean Siblings Associated with Developmental Delay and Intellectual Disability, Growth Retardation, Facial Dysmorphism, and Cerebral Infarction: A Case Report and Literature Review

The terminal 14q32 duplication has been reported often in association with other cytogenetic abnormalities, and individuals with this specific duplication showed varying degrees of developmental delay/intellectual disability (DD/ID) and growth retardation (GR), and distinct facial dysmorphisms. Herein, based on the limited cases of terminal duplication of 14q32 known to date, we present new affected siblings presenting with DD/ID, GR, and facial dysmorphism, as well as cerebral infarction caused by recurrent de novo der(14)t(14;14)(p11.2;q32.1) leading to terminal duplication of 14q32. We used coverage analysis generated via duo exome sequencing, performed chromosomal microarray (CMA) as a confirmatory test, and compared our findings with those reported previously. Coverage analysis generated via duo exome sequencing revealed a 17.2 Mb heterozygous duplication at chromosome 14q32.11-q32.33 with a Z ratio ranging between 0.5 and 1 in the proband and her elder brother. As a complementary method, CMA established a terminal duplication described as the arr[hg19]14q32.11q32.33(90,043,558_107,258,824)x3 in the proband and her elder brother; however, the parents and other siblings showed normal karyotyping and no abnormal gain or loss of CMA results. Five candidate genes, BCL11B, CCNK, YY1, DYNC1H1, and PACS2, were associated with the clinical phenotypes in our cases. Although the parents had normal chromosomes, two affected cases carrying terminal duplication of 14q32 can be explained by gonadal mosaicism. Further studies are needed to establish the association between cerebrovascular events and terminal duplication of chromosome 14q32, including investigation into the cytogenetics of patients with precise clinical descriptions.

Ultrasound prenatal diagnosis of a de novo 14q distal duplication associated with foetal anomalies: a case report

Objectives

Partial trisomy 14q is a rare chromosomal abnormality with an extremely variable phenotype ranging from mild to severe forms of malformation. Most of the cases described in literature are postnatal clinical findings although few prenatal cases have been reported.

Case presentation

A 33-year-old woman at 21+6 weeks’ gestation was referred to our hospital for a detailed foetal ultrasound with suspected partial agenesis of corpus callosum and ureterocele. On examination, we found a short corpus callosum and ureterocele with a duplicated right renal collecting system. Moreover, there was an intrarotation of left foot with a prominent part departing from the ankle, both thighs appeared thicker, a thickening of the nuchal fold, a mild hypertelorism and a thick heterogeneous placenta. The patient underwent magnetic resonance imaging (MRI), which confirmed the foetal anomalies. The couple opted for a termination of pregnancy. Chromosome analysis and molecular karyotyping of amniocytes revealed a de novo rearrangement of chromosome 14 with an interstitial gain 14q31.1–14q32.22 and a terminal deletion 14q32.33.

Conclusions

The majority of partial trisomy 14q reporter are postnatal diagnoses. Improvement in the quality of foetal imaging and molecular techniques have made possible to identify many genetic syndromes prenatally. In our opinion, anomalies of the brain, urinary system and limbs may be the core findings of trisomy 14q. To our knowledge, no such case has ever been described previously.