CALR gene mutational profile in myeloproliferative neoplasms with non-mutated JAK2 in Moroccan patients: A case series and germline in-frame deletion.

BACKGROUND: The discovery of somatic mutations within the gene encoding calreticulin (CALR) in 2013 represented a major milestone in the molecular diagnosis of BCR-ABL negative myeloproliferative neoplasms (MPN). In fact, exome sequencing revealed that most patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF) lacking JAK2 or MPL mutations, harbor somatic insertion and/or deletion in exon 9 of CALR gene. In this study, we identified the first CALR gene mutational landscape in Moroccan patients with MPN nonmutated for the JAK2 gene. METHODS: We performed Sanger sequencing of exon 9 of CALR gene in blood samples obtained from 33 Moroccan patients with ET or PMF non-mutated for JAK2. RESULTS: Of the 33 patients analyzed, we detected eight distinct variants in 15 patients (45.4%); six indel mutations, five with type 1 recurrent 52bp deletion, four with type 2 recurrent 5bp insertion and one in frame deletion which was found to be a germline variant suggesting a very rare condition in MPN. CONCLUSION: This is the first cohort reported in CALR gene mutation analysis in Morocco. Our results were concordant with studies reported up to date and very encouraging in promoting the molecular diagnosis of myeloproliferative neoplasms in Moroccan patients. Moreover, the presence of a germline in frame deletion in a symptomatic patient should undermine the effectiveness of sizing assays without DNA sequencing in the diagnosis of CALR mutations.

[Three cases of Hutchinson-Gilford progeria syndrome]. / Syndrome d'Hutchinson-Gilford (progéria). À propos de 3 cas.

Progeria, or Hutchinson-Gilford syndrome, is a rare genetic disease, characterized by several clinical features that develop in childhood, in particular, an accelerated aging aspect. Its incidence is 1-4 per 8 million newborns. Children with progeria syndrome usually appear normal at birth and in early infancy. Profound failure to thrive occurs during the 1st year. Characteristic facies, partial alopecia progressing to total alopecia, loss of subcutaneous fat, stiffness of joints, bone changes, and abnormal tightness of the skin over the abdomen and upper thighs usually become apparent during the 2nd to 3rd years. Motor and mental development is normal. Patients develop severe atherosclerosis. Death occurs as a result of complications of cardiac or cerebrovascular disease (heart attack or stroke) generally between ages 6 and 20 years. The diagnosis of Hutchinson-Gilford progeria syndrome (HGPS) is based on recognition of common clinical features and the detection of the recurrent p.Gly608Gly mutation in exon 11 of the LMNA gene, which is present in almost all individuals with HGPS. We present here 3 patients aged 5, 11, and 12 years referred to genetic consultation for dysmorphic facies and failure to thrive. After careful clinical examination and paraclinical assessment, the diagnosis of progeria syndrome was raised. We performed molecular analysis for the 3 patients by searching for the recurrent mutation c.1824C>T (p.Gly608Gly) of the LMNA gene, which was found only in 1 patient. We discuss the geneticist's role in the diagnosis of rare dysmorphic syndromes and their genetic counseling. We also analyze the clinical spectrum of HGPS by comparing the 3 patients.