Mutations in cytokine receptor-like factor 1 (CRLF1) account for both Crisponi and cold-induced sweating syndromes

Abstract

Crisponi syndrome is a rare autosomal recessive disorder characterized by congenital muscular contractions of facial muscles, with trismus in response to stimuli, dysmorphic features, bilateral camptodactyly, major feeding and respiratory difficulties, and access of hyperthermia leading to death in the first months of life. The overlap with Stuve-Wiedemann syndrome (SWS) is striking, but the two conditions differ in that congenital lower limb bowing is absent in Crisponi syndrome, whereas it is a cardinal feature of SWS. We report here the exclusion of the leukemia inhibitory factor receptor gene in Crisponi syndrome and the identification of homozygote or compound heterozygote cytokine receptor-like factor 1 (CRLF1) mutations in four children from three unrelated families. The four mutations were located in the immunoglobulin-like and type III fibronectin domains, and three of them predicted premature termination of translation. Using real-time quantitative polymerase chain reaction, we found a significant decrease in CRLF1 mRNA expression in patient fibroblasts, which is suggestive of a mutation-mediated decay of the abnormal transcript. CRLF1 forms a heterodimer complex with cardiotrophin-like cytokine factor 1, and this heterodimer competes with ciliary neurotrophic factor for binding to the ciliary neurotrophic factor receptor (CNTFR) complex. The identification of CRLF1 mutations in Crisponi syndrome supports the key role of the CNTFR pathway in the function of the autonomic nervous system.

Figure 1.

A, Pedigrees and segregation of the CRLF1 mutations identified in the three families with Crisponi syndrome. B, Exon-intron structure of the CRLF1 gene. Mutations are located in the region encoding the Ig and FNIII domains. wt = Wild type.

Figure 2.

Schematic representation of the LIFR and CNTFR pathways (from the work of Plun-Favreau et al.8). Binding of LIF to the LIFR complex (gp130-gp190) and binding of CNTF or CRLF1-CLCF1 to the CNTFR complex (CNTFR-gp130-gp190) activate the JAK/STAT pathway.

Figure 3.

RT-PCR detection of CRLF1 transcripts. RT-PCR analyses were done using RNA isolated from control muscle, chondrocytes, and brain from fibroblasts of controls (C) and patients (1, 3, and 4). Thirty PCR cycles were performed at an annealing temperature of 60°C to amplify a 381-bp fragment specific to the CRLF1 gene (forward primer 5′-AAGAACATGAAGGACTTGACCTG-3′; reverse primer 5′-GTATTTGGCTTGAAAGAGGAAATC-3′). Sense and antisense primers used for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) amplification were 5′-AGACAGCCGCATCTTCTTGT-3′ and 5′-CCACAGTCTTCTGAGTGGCA-3′ (product length 587 bp). The specific RNA transcript was found in control tissues but was barely detectable in Crisponi syndrome fibroblasts.

Figure 4.

Quantitative analysis of CRLF1 gene expression in fibroblasts from patients 1, 3, and 4. The relative amounts of CRLF1 mRNA levels compared with β-actin mRNA levels were determined for controls and for the three patients. The results shown are means ± SDs of two independent experiments. In each experiment, samples were run in triplicate.