Partial trisomy 17q and a generalised bone dysplasia in a 12 week fetus

Road to a rare diagnosis: Description of novel unbalanced translocation causing partial trisomy 17p

Trisomy 17 is a rare chromosomal disorder. Existing literature on the topic is limited and mostly refer to mosaic Trisomy 17 cases. Our report summarizes the 70‐day clinical course of a late preterm neonate with partial Trisomy 17p karyotype 46,XY,der(14)t(14;17)(p11.1;p11.2) dpat. Trisomy 17 due to unbalanced translocation is rare, and our case elaborates the clinical presentation with intestinal malfunction without any anatomical pathology and urethral diverticulum and the ethical dilemma in decision‐making. The male proband was born at 35 weeks with antenatal findings of multiple neurological and other abnormalities such as cystic hygroma, absent corpus collosum, high riding third ventricle, absent cavum septum pellucidum, indented occiput, absent ductus venous, and intrauterine growth restriction. The postnatal findings included significant facial dysmorphisms with short palpebral fissures, hypertelorism, low set ears, micrognathia, hirsutism, and single palmar creases, central hypotonia, and hyperreflexia of upper limbs bilaterally. Genital‐urinary assessment revealed a urinary diverticulum and significantly underdeveloped scrotum with undescended testes. Infant had excessive irritability and resistance to sleep despite increasing doses of analgesia and sedation, and persistent respiratory and feeding difficulties. Enteral nutrition could not be established due to profuse and persistent diarrhea, necessitating use of total parenteral nutrition. Microarray assay exhibited a pathogenic copy number gain of approximately 21.4 Mb of chromosome region 17p13.3p11.2. Follow‐up chromosome analysis and FISH revealed an abnormal male karyotype with a derivative chromosome 14, resulting from an unbalanced translocation between the short arm of one chromosome 14 and the short arm of one chromosome 17, effectively resulting in trisomy 17p11.2. It was derived from a paternal balanced t(14;17)(p11.1;p11.2) as shown by chromosome analysis and FISH studies. The rarity of this chromosomal disorder contributed to difficulty with prognosis and led to bioethical dilemma regarding life‐sustaining measures and quality of life. Through shared decision‐making processes and in consideration of poor prognosis, parents decided to withdraw life‐sustaining care and the proband died at postnatal day of life 70.

Repair of Protruding Bilateral Cleft Lip and Palate With Staged Premaxilla Setback Osteotomy, Cheiloplasty, and Palatoplasty in Trisomy 17p Patient: A Review of Syndromic Clinical Characteristic

Chromosome 17 duplication is correlated with an increased risk of developmental delay, birth defects, and intellectual disability. Here, we reported a female patient with trisomy 17 on the whole short arm with bilateral complete cleft lip and palate (BCLP). This study will review the surgical strategies to reconstruct the protruding premaxillary segment, cleft lip, and palate in trisomy 17p patient.

The patient had heterozygous pathogenic duplication of chromosomal region chr17:526-18777088 on almost the entire short arm of chromosome 17. Beside the commonly found features of trisomy 17p, the patient also presented with BCLP with a prominent premaxillary portion. Premaxillary setback surgery was first performed concomitantly with cheiloplasty. The ostectomy was performed posterior to the vomero-premaxillary suture (VPS). The premaxilla was firmly adhered to the lateral segment and the viability of philtral flap was not compromised. Two-flap palatoplasty with modified intravelar veloplasty (IVV) was performed 4 months after.

Successful positioning of the premaxilla segment, satisfactory lip aesthetics, and vital palatal flap was obtained from premaxillary setback, primary cheiloplasty, and subsequent palatoplasty in our trisomy 17p patient presenting with BLCP. Postoperative premaxillary stability and patency of the philtral and palatal flap were achieved. Longer follow-up is needed to evaluate the long-term effects of our surgical techniques on inhibition of midfacial growth. However, the benefits that the patient received from the surgery in improving feeding capacity and facial appearance early in life outweigh the cost of possible maxillary retrusion.

Maternal germline factors associated with aneuploid pregnancy loss: a systematic review

BACKGROUND

Miscarriage describes the spontaneous loss of pregnancy before the threshold of viability; the vast majority occur before 12 weeks of gestation. Miscarriage affects one in four couples and is the most common complication of pregnancy. Chromosomal abnormalities of the embryo are identified in ∼50% of first trimester miscarriages; aneuploidy accounts for 86% of these cases. The majority of trisomic miscarriages are of maternal origin with errors occurring during meiotic division of the oocytes. Chromosome segregation errors in oocytes may be sporadic events secondary to advancing maternal age; however, there is increasing evidence to suggest possible maternal germline contributions to this.

OBJECTIVE AND RATIONALE

The objective of this review was to appraise critically the existing evidence relating to maternal germline factors associated with pregnancy loss secondary to embryo aneuploidy, identify limitations in the current evidence base and establish areas requiring further research.

SEARCH METHODS

The initial literature search was performed in September 2019 and updated in January 2021 using the electronic databases OVID MEDLINE, EMBASE and the Cochrane Library. No time or language restrictions were applied to the searches and only primary research was included. Participants were women who had suffered pregnancy loss secondary to numerical chromosomal abnormalities of the embryo. Study identification and subsequent data extraction were performed by two authors independently. The Newcastle-Ottawa Scale was used to judge the quality of the included studies. The results were synthesized narratively.

OUTCOMES

The literature search identified 2198 titles once duplicates were removed, of which 21 were eligible for inclusion in this systematic review. They reported on maternal germline factors having variable degrees of association with pregnancy loss of aneuploid origin. The Online Mendelian Inheritance in Man (OMIM) gene ontology database was used as a reference to establish the functional role currently attributed to the genes reported. The majority of the cases reported and included were secondary to the inheritance of maternal structural factors such as Robertsonian translocations, deletions and insertions. Germline factors with a plausible role in aneuploid pregnancy loss of maternal origin included skewed X-inactivation and CGG repeats in the fragile X mental retardation (FMR1) gene. Studies that reported the association of single gene mutations with aneuploid pregnancy loss were conflicting. Single gene mutations with an uncertain or no role in aneuploid pregnancy loss included mutations in synaptonemal complex protein 3 (SYCP3), mitotic polo-like kinase 4 (PLK4) and meiotic stromal antigen 3 (STAG3) spindle integrity variants and 5,10-methylenetetrahydrofolate reductase (MTHFR).

WIDER IMPLICATIONS

Identifying maternal genetic factors associated with an increased risk of aneuploidy will expand our understanding of cell division, non-disjunction and miscarriage secondary to embryo aneuploidy. The candidate germline factors identified may be incorporated in a screening panel for women suffering miscarriage of aneuploidy aetiology to facilitate counselling for subsequent pregnancies.

A case report of chromosome 17q22-qter trisomy with distinct clinical presentation and review of the literature

Terminal 17q trisomy is very rare but a recognizable genetic syndrome. The majority of cases reported are inherited from a balanced translocation carrier. This syndrome involves many organs and the severity ranges from mild to severe depending on the size of the 17q gain.

Partial trisomy 17q22-qter and partial monosomy Xq27-qter in a girl with a de novo unbalanced translocation due to a postzygotic error: case report and review of the literature on partial trisomy 17qter

Partial trisomy 17q22-qter is a rare but well-recognized clinical entity. We present a case of partial trisomy for the long arm of chromosome 17, which was detected in a female infant with severe psychomotor and somatic retardation, Stargardt disease, short limbs, and numerous minor anomalies. Differential chromosomal staining demonstrated an excess of genetic material on the long arm of the late replicating X chromosome. FISH and DNA polymorphism analysis showed that the extra material belonged to the distal part of the long arm of chromosome 17 and that there was a partial monosomy of the distal part of the long arm of the derivative X chromosome. The breakpoint regions of this translocation were identified by molecular analysis using polymorphic microsatellite markers on human chromosomes 17 and X. The origin of the abnormal X chromosome was found to be paternal, whereas the origin of the duplicated part of chromosome 17 was maternal. The unbalanced translocation between the paternal X and the maternal chromosome 17 is, therefore, suggested to be due to a postzygotic error.

Sibs lacking characteristic features of duplication of distal 17q

Two brothers with karyotype 46,XY,-16,+der(16),t(16;17)(q24.3;q25.1)pat are presented. It is commonly thought that duplication of distal 17q results in a clinically recognisable syndrome. Although our cases had several features often seen in patients with autosomal chromosome aberrations, they did not have any of the specific features found in other patients with this duplication.