%0 Journal Article
%T Chromosome 22q11.2 microdeletion in monozygotic twins with discordant phenotype and deletion size
%A Ashutosh Halder
%A Manish Jain
%A Isha Chaudhary
%A Binuja Varma
%J Molecular Cytogenetics
%D 2012
%I BioMed Central
%R 10.1186/1755-8166-5-13
%X The 22q11.2 microdeletion syndrome is the most common microdeletion syndrome with an estimated incidence of one in 4000 to 6,000 live births and mostly spontaneous [1-3]. The 22q11.2 microdeletion is found in patients with DiGeorge syndrome, Velocardiofacial syndrome and Conotruncal anomaly face syndrome [4]. It is characterized by wide spectrum of clinical manifestations, including craniofacial (cleft palate, velopharyngeal insufficiency), thymic and parathyroid defects as well as cardiovascular (outflow tract and aortic arch) malformations [5]. Almost all the cases result from a common deletion of the chromosome 22q11.2 locus. The FISH is the prime method for diagnosis of this microdeletion syndrome.Several reports have mentioned phenotypic discordance between the monozygotic twins with 22q11.2 microdeletion [6-12]. No definite mechanism has been demonstrated until now for the discordant phenotype. However, somatic mosaicism, post zygotic second hit or environmental effects have been proposed. We report on a pair of monozygotic male twins with 22q11.2 microdeletion and discordant phenotype resulting from altered deletion size.A four weeks old baby boy was presented in the pediatric emergency with recurrent intractable seizures, central cyanosis and unconsciousness. During evaluation in the emergency, baby had an attack of cardiopulmonary arrest. The baby was revived and kept on the ventilator. On physical examination tachycardia & systolic murmur was noted. ECG was suggestive of ventricular tachycardia. X-ray examination of chest showed cardiomegaly. Repeated blood calcium level showed hypocalcemia, despite calcium and vitamin D. The baby was suspected to have DiGeorge Syndrome with major cardiac malformation and cardiac failure. Blood sample was sent for 22q11.2 microdeletion study. The baby was expired on sixth week of life despite intensive care, including artificial life support assistance. There was no history of antenatal complications. The baby was fine for
%U http://www.molecularcytogenetics.org/content/5/1/13