ORPHA: 481662; DO: 0060386;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 20q11.23 | ?Chilblain lupus 2 | 614415 | Autosomal dominant | 3 | SAMHD1 | 606754 |
A number sign (#) is used with this entry because of evidence that chilblain lupus-2 (CHBL2) is caused by heterozygous mutation in the SAMHD1 gene (606754) on chromosome 20q11. One such family has been reported.
Chilblain lupus is a rare cutaneous form of systemic lupus erythematosus (SLE; 152700) characterized by tender, bluish-red swellings and nodules on the hands, feet, ears, and nose, with histologic changes of lupus. The phenotype is induced by cold, such that patients frequently report a worsening of lesions in the winter months (summary by Ravenscroft et al., 2011).
For a general description and a discussion of genetic heterogeneity of chilblain lupus, see CHBL1 (610448).
Ravenscroft et al. (2011) reported a mother and son with chilblain lupus. From the age of 4 years, the 46-year-old white mother experienced recurrent lesions, particularly prominent over the winter months, affecting her hands, feet, buttocks, and thighs. She also had sun sensitivity with a tendency to develop a sunburn-like reaction with minimal sun exposure. She developed angiomatous lesions on the fingers, which became persistent. Biopsy of chilblain skin demonstrated a florid lymphocytic vasculitis, with papillary dermal edema, interface dermatitis, and keratinocyte necrosis, consistent with lupus. She was managed with nifedipine over the winter months and hydroxychloroquine plus sun block in the summer. At age 3 months, her 15-year-old son developed chilblains on the feet, fingers, and ears. Later, he also experienced photosensitivity with a sunburn-like reaction to sunlight, and developed fixed angiomatous lesions on the fingers. Both patients were in otherwise good health.
The transmission pattern of chilblain lupus in the family reported by Ravenscroft et al. (2011) was consistent with autosomal dominant inheritance.
In a mother and son with chilblain lupus, Ravenscroft et al. (2011) identified a heterozygous mutation in the SAMHD1 gene (I201N; 606754.0011).
Ravenscroft, J. C., Suri, M., Rice, G. I., Szynkiewicz, M., Crow, Y. J. Autosomal dominant inheritance of a heterozygous mutation in SAMHD1 causing familial chilblain lupus. (Letter) Am. J. Med. Genet. 155A: 235-237, 2011. [PubMed: 21204240] [Full Text: https://doi.org/10.1002/ajmg.a.33778]