Prevalence of 22q11.2 microdeletion in 146 patients with cardiac malformation in a referral hospital of North India

<p>Abstract</p> <p>Background</p> <p>The 22q11.2 microdeletion syndrome is a common condition that is associated with cardiac as well as extra-cardiac manifestations. Its prevalence and manifestations from north India has not been reported. This study was designed to determine the prevalence and ability of clinical criteria to predict 22q11.2 microdeletion.</p> <p>Methods</p> <p>A total of 146 cases of cardiac malformation requiring tertiary care at a teaching hospital were prospectively screened for 22q11.2 microdeletion using fluorescence in situ hybridization test. Detailed clinical information was obtained as per guidelines of Tobias, <it>et al </it>(1999).</p> <p>Results</p> <p>Nine out of 146 patients (6.16%) was found to have 22q11.2 microdeletion. All the positive patients showed the presence of extra-cardiac features of 22q11.2 microdeletion syndrome. None of the cases with isolated cardiac defect were positive for microdeletion.</p> <p>Conclusions</p> <p>It seems that 22q11.2 microdeletion syndrome is over-suspected in children with isolated congenital heart defects. Screening for 22q11.2 microdeletion should be considered in those cardiac malformation cases which have extra-cardiac manifestations in the form of facial dysmorphism and hypocalcaemia.</p

Characterization of greater middle eastern genetic variation for enhanced disease gene discovery

The Greater Middle East (GME) has been a central hub of human migration and population admixture. The tradition of consanguinity, variably practiced in the Persian Gulf region, North Africa, and Central Asia1-3, has resulted in an elevated burden of recessive disease4. Here we generated a whole-exome GME variome from 1,111 unrelated subjects. We detected substantial diversity and admixture in continental and subregional populations, corresponding to several ancient founder populations with little evidence of bottlenecks. Measured consanguinity rates were an order of magnitude above those in other sampled populations, and the GME population exhibited an increased burden of runs of homozygosity (ROHs) but showed no evidence for reduced burden of deleterious variation due to classically theorized ‘genetic purging’. Applying this database to unsolved recessive conditions in the GME population reduced the number of potential disease-causing variants by four- to sevenfold. These results show variegated genetic architecture in GME populations and support future human genetic discoveries in Mendelian and population genetics

Mutation analysis of Indian patients with urea cycle defects

Molecular testing for a specific metabolic disorder remains the gold standard due to its high specificity and sensitivity and possibility of accurate prenatal diagnosis. We report four cases of urea cycle defect where mutational analysis of the involved genes was performed and subsequently, prenatal diagnosis could be offered to one of the family

Mosaic 22q11.2 microdeletion syndrome: diagnosis and clinical manifestations of two cases

Abstract Chromosome 22q11.2 microdeletion syndrome is due to microdeletion of 22q11.2 region of chromosome 22. It is a common microdeletion syndrome however mosaic cases are very rare and reported only few previous occasions. In this report we describe two unrelated male children with clinical features consistent with 22q11.2 microdeletion syndrome characterized by cardiac defect, facial dysmorphism and developmental deficiency. One of the cases also had trigonocephaly. Interphase & metaphase FISH with 22q11.2 probe demonstrated mosaicism for hemizygous deletion of 22q11.2 region. Mosaicism is also observed in buccal cells as well as urine cells. Parents were without any deletion. These two cases represent rare cases of mosaic 22q11.2 microdeletion syndrome.</p

Fluorescence in situ hybridization (FISH) using non-commercial probes in the diagnosis of clinically suspected microdeletion syndromes

Background & objectives: Microdeletion syndromes are characterized by small (<5 Mb) chromosomal deletions in which one or more genes are involved. These are frequently associated with multiple congenital anomalies. The phenotype is the result of haploinsufficiency of genes in the critical interval. Fluorescence in situ hybridization (FISH) technique is commonly used for precise genetic diagnosis of microdeletion syndromes. This study was conducted to assess the role of FISH in the diagnosis of suspected microdeletion syndrome. Methods: FISH was carried out on 301 clinically suspected microdeletion syndrome cases for the confirmation of clinical diagnosis using non-commercial probes. Of these, 177 cases were referred for 22q11.2 microdeletion, 42 cases were referred for William syndrome, 38 cases were referred for Prader Willi/Angelman and 44 cases were referred for other suspected microdeletion syndromes. Results: FISH was confirmatory in 23 cases only (7.6%). There were 17 cases of 22q11.2 microdeletion, four cases of Prader Willi syndrome and two cases of William syndrome. Interpretation & conclusion: We conclude that FISH should not be the method of choice for clinically suspected microdeletion syndromes. We propose to follow strict clinical criteria for FISH testing or preferably to follow better methods (genotype first approach). Whole genome screening may be used as first line of test and FISH may be used for confirmation of screening result, screening of family members and prenatal diagnosis

Antenatal diagnosis of Lowe syndrome.

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