Bloom Syndrome

Autosomal recessive inherited disorder characterized by prenatal and postnatal growth retardation, photosensitivity, telangiectasias, skin pigment anomalies, and increased risk of malignancies most likely as a consequence of chromosomal instability.

(Figure)

Congenital Telangiectatic Erythema; Bloom-Torre-Machacek Syndrome.

1:160,000 live births. More common in Ashkenazi Jews from Eastern Europe.

Autosomal recessive. Gene map locus 15q26.1.

The protein BLM encoded by the normal gene acts in the maintenance of genomic stability. A mutation in this gene results in Bloom Syndrome. Spontaneous chromosome breakage with exchanges between homologous chromosome segments lead to increased sister chromatid exchanges and are assumed to be responsible for the phenotype and the predisposition to neoplasias.

Clinical signs plus chromosomal and DNA analysis. Amniocentesis for amniotic fluid cell culture with assessment of the number of sister chromatid exchanges allows prenatal diagnosis.

Prenatal and postnatal growth retardation are hallmarks of this syndrome and usually the first reason to seek medical attention. Clinical signs include dolichocephaly and malar hypoplasia resulting in a “bird-like” face, photosensitivity with telangiectasias in the face and other sun-exposed areas (butterfly-like midface distribution; plaques or macules in other locations), and café-au-lait spots. Pulmonary fibrosis, bronchiectasis, cardiomyopathy, primary hypogonadism and mental retardation are variable findings. Adult-onset diabetes mellitus may occur in the second or third decade of life. Immunocompromise is caused by decreased levels of IgM and IgA and can result in life-threatening gastrointestinal and respiratory infections. Predisposition to neoplasias is another important feature, with an up to 300-fold increased risk of malignancies compared to the normal population (especially lymphomas, leukemias, squamous cell carcinomas, and gastrointestinal adenocarcinomas). Approximately 20% of patients will experience one (or more) neoplasia(s), which may present as early as 4 years of age but is most common in the mid-twenties for leukemias and lymphomas and in the mid-thirties for solid tumors. Patients are at risk for developing diabetes mellitus in the second or third decade of life.

Obtain a full history. Check blood glucose profile and levels in case of diabetes mellitus. Rule out mediastinal mass in the presence of lymphoma or leukemia. Check respiratory and cardiac function (clinical, chest radiography, echocardiography, arterial blood gas analysis, pulmonary function tests).

Strict asepsis for these patients is mandatory and reverse isolation must be considered. Enforce aggressive pulmonary toilet in the presence of bronchiectases. Perioperative cardiac and respiratory monitoring should be considered.

Avoid myocardial depressant drugs in the presence of cardiomyopathy. Consider prophylactic antibiotics as in immunodeficient patients.

Porphyrias: a group of disorders characterized by enzymatic defects in the heme biosynthesis. Depending on the primary location of the defect, the porphyrias are classified as erythropoietic and hepatic forms.

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