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Neurology India, Vol. 58, No. 4, July-August, 2010, pp. 670-671 Letter To Editor Xp21.2 contiguous gene syndrome due to deletion involving glycerol kinase and Duchenne muscular dystrophy loci Jamroz Ewa, Paprocka Justyna, Popowska Ewa, Pytel Justyna, Ciara Elzbieta, Adamowicz Maciej Department of Child Neurology, Silesian Medical University, Katowice Correspondence Address:Department of Child Neurology, Silesian Medical University, Katowice, justyna.paprocka@interia.pl Date of Acceptance: 24-Jun-2010 Code Number: ni10180 PMID: 20739824 DOI: 10.4103/0028-3886.68690 Sir, Glycerol kinase deficiency (GKD, MIM 307030) is an X-linked recessive metabolic disorder, characterized by hyperglycerolemia, glyceroluria and "pseudo-hypertriglyceridemia". [1],[2] It can occur as an isolated glycerol kinase (GK) deficiency or in combination with adrenal hypoplasia congenita (AHC, MIM 300200) or/and Duchenne muscular dystrophy (DMD, MIM 310200). GKD is due to microdeletions in the Xp21.2-p21.3 region often involving the GK, dosage-sensitive sex reversal locus and the adrenal hypoplasia congenita locus on the X chromosome (DAX1) and/or the Duchenne muscular dystrophy (DMD) genes. [2],[3],[4] A 2-year-old boy, born after 39 weeks of gestation, had an Apgar score of 10 points, a birth weight of 3050 g, length of 50 cm, and head circumference of 34 cm. Pregnancy and delivery period were uncomplicated. In the neonatal period, the boy was hospitalized because of weight loss and dehydration. At the age of 4 months, he showed a failure to thrive. The findings on neurological examination were: the head circumference 42 cm, strabismus convergens, axial hypotonia, and increased muscle tone in extremities, normal deep tendon reflexes. Laboratory analyses showed increased serum level of liver enzymes alanine and aspartate transaminases (ALT: 220 U/l; AST: 212 U/l), creatine kinase (CK 10 818 U/l), lactate dehydrogenase (LDH 1062 U/l), and plasma triglycerides′level was 1158 mg/dl. Electromyography yielded a myopathic pattern. Computerized tomography (CT) of the head showed widening of the pericerebellar spaces. Urine analysis revealed massive glyceroluria. GK activity in leukocytes was 1.3% of control value. Genomic DNA was analyzed by polymerase chain reaction (PCR) using primers for GK gene (exons 1-19), DAX-1 gene (exons 1 and 2) and DMD gene (exons 1, 2, 3, 45, 60, 71 and 79). The deletion involved the whole GK and DMD locus. At the age of 22 months, the patient showed developmental delay. Motor skills were estimated at the level of 10 months and cognitive skills at the level of 11 months of age. Laboratory investigations revealed the following enzyme activities: ALT: 425 U/l, AST: 217 U/l, LDH: 835 U/l, CK: 9746 U/l. Within complex GKD (cGKD), the most common combination is lack of all three genes DAX-1-GK-DMD. Deletion of GK-DMD genes is described in less than 5% of patients. [2] Patients with cGKD usually have mental retardation if they have deletions extending into the DMD gene and/or involving a significant extension telomeric from DAX1. [1],[4] Zhang et al. showed that nearly all patients with deletions involving DAX1, but not DMD, had mental retardation if IL1RAPL1 (interleukin-1 receptor accessory protein-like gene 1) was deleted. [4] The diagnosis of GKD-DMD is essential to foresee metabolic decompensations. Life-threatening episodes in childhood can be avoided by frequent carbohydrate meals and avoidance of excessive physical activity. [1],[2],[3] References
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