B-cell receptor signaling and genetic lesions in TP53 and CDKN2A/CDKN2B cooperate in Richter transformation.

B-cell receptor (BCR) signals play a critical role in the pathogenesis of chronic lymphocytic leukemia (CLL), but their role in regulating CLL cell proliferation has still not been firmly established. Unlike normal B cells, CLL cells do not proliferate in vitro upon engagement of the BCR, suggesting that CLL cell proliferation is regulated by other signals from the microenvironment, such as those provided by Toll-like receptors or T cells. Here, we report that BCR engagement of human and murine CLL cells induces several positive regulators of the cell cycle, but simultaneously induces the negative regulators CDKN1A, CDKN2A, and CDKN2B, which block cell-cycle progression. We further show that introduction of genetic lesions that downregulate these cell-cycle inhibitors, such as inactivating lesions in CDKN2A, CDKN2B, and the CDKN1A regulator TP53, leads to more aggressive disease in a murine in vivo CLL model and spontaneous proliferation in vitro that is BCR dependent but independent of costimulatory signals. Importantly, inactivating lesions in CDKN2A, CDKN2B, and TP53 frequently co-occur in Richter syndrome (RS), and BCR stimulation of human RS cells with such lesions is sufficient to induce proliferation. We also show that tumor cells with combined TP53 and CDKN2A/2B abnormalities remain sensitive to BCR-inhibitor treatment and are synergistically sensitive to the combination of a BCR and cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor both in vitro and in vivo. These data provide evidence that BCR signals are directly involved in driving CLL cell proliferation and reveal a novel mechanism of Richter transformation.

Severe digital malformations in a rare variant of fibrodysplasia ossificans progressiva.

A 16-year-old girl with a history of nontraumatic swelling of both forearms, osteochondromas of the knees, heterotopic ossification of the neck and back, severe malformations of all digits with hypoplastic or absent nails, alopecia partialis of the scalp, and moderate cognitive impairment was seen for diagnostic evaluation. Whole exome sequencing identified an activating mutation of ACVR1 (c.983G > A; p.Gly328Glu) which confirmed a suspected FOP variant. The delayed diagnosis of an FOP variant in this patient could have been avoided if the significance of severe digital malformations had been recognized, especially in the setting of progressive heterotopic ossification.

First Cases of Hb Agrinio Described in Patients from the Republic of Macedonia.

Previous molecular analyses of α-thalassemia (α-thal) in the Republic of Macedonia have identified the following genetic defects: -α3.7 (rightward), -(α)20.5 and - -MED I deletions and Hb Icaria [α142, Term→Lys (α2), HBA2: c.427T>A] and polyadenylation signal (polyA) [AATAAA>AATGAA (α2), HBA2: c.*92A>G] point mutations. Here, we report two unrelated patients from the Romani population in the Republic of Macedonia, homozygotes for the α2-globin gene variant Hb Agrinio [α29(B10)Leu→Pro; HBA2: c.89T>C]. To date, Hb Agrinio has been described only in individuals of Greek, Cypriot and Spanish origin. Both of our patients had early presentation of the disease (3.5 years and 2 months, respectively) with frequent blood transfusions from early infancy. They have a severe intermediate phenotype of thalassemia (Hb H disease) with hemoglobin (Hb) levels of 7.8 and 7.7 g/dL, respectively. Although the HBA2: c.89T>C mutation results in an α+ allele, the severe phenotype of the homozygotes is due to the production of hyperunstable α chains that undergo post translational precipitation. This leads to a greater degree of red cell damage and hemolytic anemia. The detection of Hb Agrinio in two unrelated families of Romani ethnic origin, may suggest it is a founder mutation in this population living in the Republic of Macedonia. Considering the severity of the clinical presentation of the homozygotes or compound heterozygotes for this rare Hb variant, a targeted molecular screening for Hb Agrinio mutation carriers should be considered in all patients of Romani ethnic origin with manifested microcytosis.

LHX4 Gene Alterations: Patient Report and Review of the Literature.

LHX4 mutations are rare in combined pituitary hormone deficiency, and even rarer in isolated GHD. We describe a 14 years old boy who was referred for investigation of short stature. Convergent strabismus, nystagmus was present. At the age of 5 years his gait was unstable. A progressive myopathy ensued. Tests of pituitary reserve showed partial IGHD (8.2 ng/ml). Other pituitary hormones were within normal range. Muscle biopsy showed congenital myopathy of undefined etiology. MRI of the brain revealed the empty sella syndrome. Targeted resequencing with a panel containing probe sets for enrichment and analysis of > 4,800 clinically relevant genes, targeting 12Mb of the human genome revealed the c.250C>T (R84C) LHX4 mutation. His father is healthy, with no myopathy or pituitary deficiencies, but has the same LHX4 mutation. This report extends the range of phenotypes associated with LHX4 gene mutations. To the best of our knowledge, we are the first to report on congenital myopathy in an LHX4 gene mutation. Forthwith, we offer a comprehensive review of the patients published so far with their clinical and genetic characteristics.

Hb G-Waimanalo [A1] or α64(E13)Asp→Asn (α1) (HBA1: c.193G>A) Observed in a Bulgarian Family.

The abnormal hemoglobin (Hb) with an aspartic acid to asparagine substitution at α64 has been found on both the α2- and α1-globin genes. It has been described in many different populations under different names, but never in Bulgaria. Using the recently proposed nomenclature, Hb G-Waimanalo [A1] refers to the HBA1: c.193G > A, while Hb G-Waimanalo [A2] refers to the HBA2: c.193G > A mutation. Here, we present the first family from Bulgaria with Hb G-Waimanalo [A1].

Novel Founder Mutation in FANCA Gene (c.3446_3449dupCCCT) Among Romani Patients from the Balkan Region.

BACKGROUND: Fanconi anemia is a rare autosomal recessive or X-linked disorder characterised by clinical and genetic heterogeneity. Most fanconi anemia patients harbour homozygous or double heterozygous mutations in the FANCA (60-65%), FANCC (10-15%), FANCG (~10%) or FANCD2 (3-6%) genes. We have already reported the FANCA variant c.190-256_283+1680del2040dupC as a founder mutation among Macedonian fanconi anemia patients of Gypsy-like ethnic origin. Here, we present a novel FANCA mutation in two patients from Macedonia and Kosovo. CASE REPORT: The novel FANCA mutation c.3446_3449dupCCCT was identified in two fanconi anemia patients with Romany ethnicity; a 2-year-old girl from Macedonia who is a compound heterozygote for a previously reported FANCA c.190-256_283+1680del2040dupC and the novel mutation and a 10-year-old girl from Kosovo who is a homozygote for the novel FANCA c.3446_3449dupCCCT mutation. The novel mutation is located in exon 35 in the FAAP20-binding domain which plays a crucial role in the FANCA-FAAP20 interaction and is required for integrity of the fanconi anemia pathway. CONCLUSION: The finding of the FANCA c.3446_3449dupCCCT mutation in two unrelated FA patients with Romani ethnicity from Macedonia and Kosovo suggests it is a founder mutation in the Romani population living in the Balkan region.