A Rare Chromosome 3 Imbalance and Its Clinical Implications

Karen Sims,Donald R Love,Emilie Payne,Ian Hayes,Roberto L P Mazzaschi,Alice M George

doi:10.1155/2012/846564

Karen Sims, Donald R Love + Show 4 more

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https://doi.org/10.1155/2012/846564

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Abstract

The duplication of chromosome 3q is a rare disorder with varying chromosomal breakpoints and consequently symptoms. Even rarer is the unbalanced outcome from a parental inv(3) resulting in duplicated 3q and a deletion of 3p. Molecular karyotyping should aid in precisely determining the length and breakpoints of the 3q+/3p− so as to better understand a child's future development and needs. We report a case of an infant male with a 57.5 Mb duplication from 3q23-qter. This patient also has an accompanying 1.7 Mb deletion of 3p26.3. The duplicated segment in this patient encompasses the known critical region of 3q26.3-q27, which is implicated in the previously reported 3q dup syndrome; however, the accompanying 3p26.3 deletion is smaller than the previously reported cases. The clinical phenotype of this patient relates to previously reported cases of 3q+ that may suggest that the accompanying 1.7 Mb heterozygous deletion is not clinically relevant. Taken together, our data has refined the location and extent of the chromosome 3 imbalance, which will aid in better understanding the molecular underpinning of the 3q syndrome.

Highlights

The genetic analysis of infants with multiple congenital abnormalities is a very important aid in understanding a child’s future prognosis and development
The duplication of chromosome 3q is a rare genetic disorder resulting in mental retardation, seizures, broad nose, cardiac, renal, and genital malformations [2]
A one-month-old male presented with a large ventricular septal defect (VSD), large posterior and anterior fontanelle, dysmorphic features, single palmar crease, under-developed testes and mild seizures

Summary

Introduction

The genetic analysis of infants with multiple congenital abnormalities is a very important aid in understanding a child’s future prognosis and development. The duplication of chromosome 3q is a rare genetic disorder resulting in mental retardation, seizures, broad nose, cardiac, renal, and genital malformations [2]. The size of the deletion appears to correlate with severity of the phenotype such that patients with a large deletion exhibit severe malformations and mental retardation [5]. The reported breakpoints for the 3p− syndrome appear to be variable, but the 3p− phenotype is associated with deletions in the 3pter-3p25 region [6]. Reported cases of patients carrying a duplication at 3q23-ter as well as a large deletion at pter-3p25 have a fatal outcome [2]. We report a case here in which the patient has a much smaller 3p deletion in combination with the 3q23-ter duplication, and discuss whether the 3p deletion size affects patient phenotype and outcome

Case Report

Discussion

Conclusion