Interstitial deletion of chromosome 2q32-34 associated with multiple congenital anomalies and a urea cycle defect (CPS I deficieney)

M. L. Loscalzo, R. L. Galczynski, A. Hamosh, M. Summar, J. M. Chinsky, G. H. Thomas

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


A de novo deletion of the long arm of chromosome 2 at 2q31-33 was observed in the fetal anmiocyte G-banded karyotype performed because of possible multiple malformations identified by ultrasound at 23 weeks gestation. Two days after the uneventful term delivery of a 2.45 kg male, the neonate experienced cardiopulmonary decompensation and biochemical changes compatible with carbamoyl phosphate synthetase I (CPS I) deficiency (elevated ammonia with a peak of 948 μmol/L, deficiency of citrulline, and no increase in orotic acid). The child died on day 3 of life. Physical anomalies confirmed at autopsy included double superior vena cava, ectopic adrenal tissue, and metatarsus adductus. The autopsy also revealed histologic evidence consistent with CPS deficiency, most notably microvesicular steatosis of the liver and Alzheimers Type II changes with hypertrophic astrocytes in the basal ganglia. A postnatal lymphocyte karyotype confirmed the chromosome 2q31-33 deletion. Enzyme analysis on postmortem liver tissue confirmed the diagnosis of CPS deficiency. CPS I is reported to be mapped to 2q35 by NCBI ( and 2q34 by ENSEMBL (http:// The UCSC Human Genome Browser July 2003 assembly also places the gene at 2q34 ( Fluorescence in situ hybridization (FISH) analysis with a BAC clone (RP11-349G4) of CPS I demonstrated that one copy of the gene was deleted in this infant. Using additional probes corresponding to the bands in the region of deletion, we identified the deleted region as 2q32-2q34. Our observations support the CPS I map position (ENSEMBL, UCSC) at 2q34. Additionally, potential conditions associated with deletions narrowly defined by standard cytogenetic techniques merit consideration in prenatal counseling. As demonstrated here, deletions may not only result in malformations and mental retardation but also increase the likelihood of revealing mutated genes located in the undeleted region of the homologous chromosome.

Original languageEnglish (US)
Pages (from-to)311-315
Number of pages5
JournalAmerican Journal of Medical Genetics
Volume128 A
Issue number3
StatePublished - Jul 30 2004


  • CPS I
  • Carbamoyl phosphate synthetase 1 deficiency
  • Chromosome 2q
  • Urea cycle defect

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)


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