Bloom syndrome does not always present with sun-sensitive facial erythema

Bloom syndrome is an autosomal recessive condition characterized by severe pre- and postnatal growth deficiency, immunodeficiency, an increased risk for malignancies, craniofacial dysmorphisms, and "typical" erythematous sun-sensitive skin lesions of the face. This facial rash has a butterfly-shaped distribution around the nose and is usually observed for the first time during the early years of life. Though reported as being a main feature of Bloom syndrome, there seems to be phenotypic variability regarding this facial skin rash among patients. It has been previously reported that in some individuals with Bloom syndrome these sun-sensitive lesions are less prominent or even absent. In this report we describe a 36 year old woman with short stature, microcephaly, several dysmorphisms, congenital hypothyroidism and premature ovarian failure. She was diagnosed with nasopharyngeal carcinoma at 36 years of age, only a few months after her consultation at the department of Clinical Genetics. Whole Exome Sequencing demonstrated that she had Bloom syndrome caused by a compound heterozygous mutation in BLM (c.2207_2212delinsTAGATTC; p.(Tyr736Leufs*5) and c.3681del; p.(Lys1227Asnfs*52)). She did not have facial sun-sensitive erythematous rash during childhood nor adulthood. We conclude that Bloom syndrome does not always present with erythematous sun-sensitive skin lesions of the face. We would like to underline that phenotypic variation regarding this "hallmark" feature of Bloom syndrome exists. Being aware of this might prevent a delay in diagnosing this rare short-stature syndrome and, subsequently, its potential clinical implications