Chromosome 3p25 deletion in mother and daughter with minimal phenotypic effect

Prenatal diagnosis of familial 3p26.3p25.3 deletion in a pregnancy associated with a favorable fetal outcome and asymptomatic carrier parent and family members in three generations

OBJECTIVE

We present prenatal diagnosis of familial 3p26.3p25.3 deletion in a pregnancy associated with a favorable fetal outcome and asymptomatic carrier parent and family members in three generations.

CASE REPORT

A 35-year-old, gravida 2, para 1, woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age and the carrier of distal 3p deletion. She was phenotypically normal, and there was no family history of congenital anomalies. Amniocentesis revealed a karyotype of 46,XY,del(3)(p26.1). Repeat amniocentesis at 21 weeks of gestation revealed a karyotype of 46,XY,del(3)(p25.3). Simultaneous array comparative genomic hybridization (aCGH) analysis on the DNA extracted from uncultured amniocytes showed the result of arr 3p26.3p25.3 (117,735-8,709,972) × 1.0 [GRCh37 (hg19)] with an 8.59-Mb deletion of 3p26.3p25.3 encompassing 14 OMIM genes of CHL1, CNTN6, CNTN4, IL5RA, TRNT1, CRBN, SETMAR, SUMF1, ITPR1, BHLHE40, ARL8B, GRM7, LMCD1 and SSUH2. Cytogenetic analysis of parental bloods revealed a karyotype of 46,XX,del (3) (p25.3) in the mother and 46,XY in the father. The woman's 69-year-old mother and her 2-year-old elder son carried the same aberrant chromosome of 3p25.3→p26.3 deletion by conventional cytogenetic analysis but manifested no phenotypic abnormality. aCGH analysis of the peripheral bloods showed that the woman's mother and her elder son had the same 8.59-Mb deletion of 3p26.3p25.3. The woman was advised to continue the pregnancy. At 39 weeks of gestation, a 3040-g healthy male baby was delivered. When follow-up at age 2½ years, the neonate was normal in development and showed no apparent phenotypic abnormality.

CONCLUSION

Distal 3p deletion of 3p26.3p25.3 involving the OMIM genes from CHL1 to SSUH2 can be associated with no apparent phenotypic abnormality.

Familiar del3p syndrome: The uncertainty of the prognosis. A case report

The 3p deletion syndrome is an unusual condition. The few cases described are mainly de novo. We described a familial case detected in a prenatal diagnosis. Three members of the family had the 3p26.3-p26.1 deletion; however, only the son presented clinical features.

A terminal 3p26.3 deletion is not associated with dysmorphic features and intellectual disability in a four-generation family

Terminal deletions of the distal part of the short arm of chromosome 3 cause a wide range of phenotypes from normal to dysmorphic including microcephaly, developmental delay and intellectual disability. We studied the clinical consequences of a terminal deletion of the short arm of chromosome 3 in four generations of a family. The index patient is a14-month-old boy with microcephaly, corpus callosum dysgenesis, and minor dysmorphic features. Single Nucleotide Polymorphism (SNP) array analysis detected a duplication on the long arm of chromosome 6. His apparently healthy mother carries the same 6q duplication, but as an unexpected finding a terminal deletion of 2.9 Mb of the short arm of chromosome 3 was observed. Further co-segregation analysis in the family for the chromosome 3 deletion showed that with the exception of the sister of the index who has autism, speech delay, and learning problems, family members in four generations of this family are carrier of this 3p deletion and apparently healthy. To our knowledge, this is the first report of a study of this terminal 3p deletion in four generations. In this report, we review the literature on terminal 3p deletions and discuss the importance of molecular testing and reporting of copy number variants to achieve accurate genetic counseling in prenatal and postnatal screening.

Monosomy 3pter-p25.3 and trisomy 1q42.13-qter in a boy with profound growth and developmental restriction, multiple congenital anomalies, and early death

Albeit rare, 3pter-p25 monosomy or 1q42-qter trisomy syndromes have been documented in the literature. Here, we report a unique case with a combination of 3pter-p25 monosomy and 1q42-qter trisomy, delineated by array comparative genomic hybridization analysis. The proband was a newborn male with multiple congenital anomalies that included brain malformation, ocular anomalies, trachea-laryngomalacia, cardiac defects, intestinal malrotation, and cutaneous findings in conjunction with biochemical anomalies, profound growth and developmental restriction, and early death. To our knowledge, this is the first case report of this unique chromosomal imbalance.

3p deletion syndrome: implications for cochlear implantation

OBJECTIVE AND IMPORTANCE

To describe the role of cochlear implantation in patients with 3p deletion syndrome. Additionally, this paper will review non-mastoid approaches to the cochlea potentially used in cases of mastoid abnormalities.

CLINICAL PRESENTATION

A 23-month-old child with 3p deletion syndrome (3pDS) presented with suspected hearing loss and characteristic craniofacial abnormalities. Bilateral sensorineural hearing loss (SNHL) was confirmed. Temporal bone computed tomography showed poorly developed mastoids bilaterally.

INTERVENTION

Cochlear implantation was successfully undertaken using a retro-auricular transmeatal approach.

CONCLUSION

SNHL is commonly encountered in patients with 3pDS and can be improved by cochlear implantation. In this patient population, particular attention must be given to pre-operative imaging and possible altered mastoid anatomy may exist. In doing so, intra-operative complications can be avoided.

Microarray based analysis of an inherited terminal 3p26.3 deletion, containing only the CHL1 gene, from a normal father to his two affected children

Background

terminal deletions of the distal portion of the short arm of chromosome 3 cause a rare contiguous gene disorder characterized by growth retardation, developmental delay, mental retardation, dysmorphisms, microcephaly and ptosis. The phenotype of individuals with deletions varies from normal to severe. It was suggested that a 1,5 Mb minimal terminal deletion including the two genes CRBN and CNTN4 is sufficient to cause the syndrome.

In addition the CHL1 gene, mapping at 3p26.3 distally to CRBN and CNTN4, was proposed as candidate gene for a non specific mental retardation because of its high level of expression in the brain.

Methods and Results

we describe two affected siblings in which array-CGH analysis disclosed an identical discontinuous terminal 3p26.3 deletion spanning less than 1 Mb. The deletion was transmitted from their normal father and included only the CHL1 gene. The two brothers present microcephaly, light mental retardation, learning and language difficulties but not the typical phenotype manifestations described in 3p- syndrome.

Conclusion

a terminal 3p26.3 deletion including only the CHL1 gene is a very rare finding previously reported only in one family. The phenotype of the affected individuals in the two families is very similar and the deletion has been inherited from an apparently normal parent. As already described for others recurrent syndromes with variable phenotype, these findings are challenging in genetic counselling because of an evident variable penetrance.

Unbalanced 3;22 translocation with 22q11 and 3p deletion syndrome

This report describes a 25-day-old Turkish boy with unbalanced 3;22 translocation that includes the 22q11.2 deletion and 3p25 deletion syndrome. The karyotype was 45, XY,der(3)t(3;22)(p25;q11),-22. Although no immunological dysfunction could be demonstrated, the boy presented some manifestations of DiGeorge anomaly (DGA), which has been associated with monosomy for the same region of chromosome 22, velocardiofacial syndrome (VCFS), and the 3p deletion syndrome. Clinical features include short stature, hypertelorism, low set ears, cleft lip with cleft palate, short neck, truncus arteriosus, micropenis, clubfoot, over riding toes on right foot, four digits on left foot and growth delay. In addition he had feeding difficulties, respiratory infections, and developmental delay. Fluorescence in situ hybridization (FISH) studies confirmed loss of the proximal DiGeorge chromosomal region (DGCR). Array CGH analysis showed the deletion sites on chromosomes 3 and 22. This report documents a rare chromosomal aberration that causes the 22q11 and 3p deletion syndrome simultaneously.

The importance of case reports in advancing scientific knowledge of rare diseases

Case reports are defined as the scientific documentation of a single clinical observation and have a time-honored and rich tradition in medicine and scientific publication. Case reports represent a relevant, timely, and important study design in advancing medical scientific knowledge especially of rare diseases. While there are clear limitations to the methodology of case studies in determination of treatment and establishment of new tests, the observation of a single patient can add to our understanding of etiology, pathogenesis, natural history, and treatment of particularly rare diseases, and to the training of potential junior investigators. In recent years this class of scientific publication has come under scrutiny and disfavor among some in the medical scientific publication community and case studies are frequently relegated to the lowest rung of the hierarchy of study design. In this chapter the author will review and summarize the debate around the scientific publication of case reports in the context of the study of rare diseases and will present a taxonomy that ideally will encourage further dialogue on the topic. Future research on the importance of case reports in advancing knowledge of rare diseases is recommended.

Microarray based analysis of 3p25-p26 deletions (3p- syndrome)

Distal deletion of chromosome 3p25-pter (3p- syndrome) produces a distinct clinical syndrome characterized by low birth weight, mental retardation, telecanthus, ptosis, and micrognathia. Congenital heart disease (CHD), typically atrioventricular septal defect (AVSD) occurs in about a third of patients. Previously we reported on an association between the presence of CHD and the proximal extent of the deletion such that a CHD susceptibility gene was mapped between D3S1263 and D3S3594. In addition, we and others have suggested several candidate genes for the psychomotor retardation usually seen with constitutional 3p25 deletions. In order to further investigate genotype-phenotype correlations in 3p- syndrome we analyzed 14 patients with cytogenetically detectable deletions of 3p25 (including one patient with a normal phenotype) using Affymetrix 250K SNP microarrays. Deletion size varied from approximately 6 to 12 Mb. Assuming complete penetrance, a candidate critical region for a CHD susceptibility gene was refined to approximately 200 kb and a candidate critical region for mental retardation was mapped to an approximately 1 Mb interval containing SRGAP3 but other 3p neurodevelopmental genes including CHL1, CNTN4, LRRN1, and ITPR1 mapped outside the candidate critical interval. We suggest that current evidence suggests that SRGAP3 is the major determinant of mental retardation in distal 3p deletions.

Coexistence of an unbalanced chromosomal rearrangement and spinal muscular atrophy in an infant with multiple congenital anomalies

Unbalanced chromosomal abnormalities are frequent and account for about 10% of all chromosomal abnormalities identified in live births. Diagnosis of a coinherited neuromuscular genetic disorder in these individuals is often challenging based on the severity and variability of the phenotype resulting from the genomic imbalance. Herein, we report on a 4-month-old male with multiple congenital anomalies, craniosynostosis, dysmorphic features, and hypotonia. Karyotype analysis revealed an abnormal male karyotype: 46,XY,der(3)(3;7)(p25;q36), with partial monosomy of 3pter and partial trisomy of 7qter. The targeted array-based comparative genomic hybridization (array-CGH) validated the cytogenetic abnormality, with further elucidation of trisomy of the Sonic Hedgehog (SHH) locus on chromosome 7. Based on the severity of hypotonia in this infant, molecular analysis for spinal muscular atrophy (SMA) was performed and the common homozygous deletion of exon 7 in the survival of motor neuron 1 gene (SMN1) was identified. This case demonstrates the challenges in diagnoses of coexisting genetic disorders in infants with neuromuscular disease. A high index of suspicion in such cases is essential for appropriate case management and family risk assessment.

Significance of case reports in the advancement of medical scientific knowledge

In an Editorial Comment in 2006 Carey summarized the issues surrounding the publication of case reports in the current medical literature. In this present study, three questions about case reports are posed by the author: Do journals still publish single case reports? What do medical journals call these reports? And how should we classify reports of single clinical observations? The author examined the table of contents of 25 prominent journals and addressed the question as to whether these selected periodicals published case reports. The analysis showed that 32% of reviewed journals published case reports and 32% did not, while the remainder of journals published this class of papers but in a modified fashion and not regularly. Journals varied in what term they use to describe case reports. The author proposed a classification system for case reports in the human genetics literature. More dialogue and research is needed to examine the role of case reports in the medical scientific literature.