Journal
MOLECULAR GENETICS AND METABOLISM REPORTS
Volume 1, Issue -, Pages 176-183Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ymgmr.2014.03.004
Keywords
Lysinuric protein intolerance; Osteoporosis; Bone fractures; SLC7A7
Categories
Funding
- Medical Genetics Research Fellowship Program NIH/NIGMS [NIH T32 GM07526]
- Genzyme/ACMG Foundation
- Genomic Medicine Medical Genetics Training Award in Clinical Biochemical Genetics
- Baylor College of Medicine Intellectual and Developmental Disabilities Research Center from the Eunice Kennedy Shriver National Institute of Child Health & Human Development [HD024064, P01 HD070394]
- EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT [P30HD024064, P01HD070394] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [R01DK102641] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES [T32GM007526] Funding Source: NIH RePORTER
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Lysinuric protein intolerance (LPI) is a rare autosomal recessive inborn error of metabolism caused by mutations in SLC7A7, which encodes a component of the dibasic amino acid transporter found in intestinal and renal tubular cells. Patients typically present with vomiting, diarrhea, irritability, failure to thrive, and symptomatic hyperammonemia after protein-rich meals. Long-term complications may include pulmonary alveolar proteinosis, renal disease, and osteoporosis. We present a 5-year-old male who was followed in our skeletal dysplasia clinic for 3 years for multiple fractures, idiopathic osteoporosis, and short stature in the absence of typical features of LPI. Whole exome sequencing performed to determine the etiology of the osteoporosis and speech delay identified a nonsense mutation in SLC7A7. Chromosome micro-array analysis identified a deletion involving the second allele of the same gene, and biochemical analysis supported the diagnosis of LPI. Our patient's atypical presentation underscores the importance of maintaining a high index of suspicion for LPI in patients with unexplained fractures and idiopathic osteoporosis, even in the absence of clinical symptoms of hyperammonemia after protein rich meals or other systemic features of classical LPI. This case further demonstrates the utility of whole exome sequencing in diagnosis of unusual presentations of rare disorders for which early intervention may modify the clinical course. (C) 2014 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license
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