Human inherited CCR2 deficiency underlies progressive polycystic lung disease.

We describe a human lung disease caused by autosomal recessive, complete deficiency of the monocyte chemokine receptor C-C motif chemokine receptor 2 (CCR2). Nine children from five independent kindreds have pulmonary alveolar proteinosis (PAP), progressive polycystic lung disease, and recurrent infections, including bacillus Calmette Guérin (BCG) disease. The CCR2 variants are homozygous in six patients and compound heterozygous in three, and all are loss-of-expression and loss-of-function. They abolish CCR2-agonist chemokine C-C motif ligand 2 (CCL-2)-stimulated Ca2+ signaling in and migration of monocytic cells. All patients have high blood CCL-2 levels, providing a diagnostic test for screening children with unexplained lung or mycobacterial disease. Blood myeloid and lymphoid subsets and interferon (IFN)-γ- and granulocyte-macrophage colony-stimulating factor (GM-CSF)-mediated immunity are unaffected. CCR2-deficient monocytes and alveolar macrophage-like cells have normal gene expression profiles and functions. By contrast, alveolar macrophage counts are about half. Human complete CCR2 deficiency is a genetic etiology of PAP, polycystic lung disease, and recurrent infections caused by impaired CCL2-dependent monocyte migration to the lungs and infected tissues.

Mutations in the VPS13B Gene in Iranian Patients with Different Phenotypes of Cohen Syndrome.

Cohen syndrome is a rare autosomal recessive disorder characterized by hypotonia, obesity, developmental delay, mental retardation, and facial, oral, ophthalmic, and limb deformities. Mutations in VPS13B have been found to be responsible for this disorder. In the current report, we have assessed three Iranian families with developmental delay and skeletal deformities. Whole exome sequencing of the affected probands led to identification of the underlying genetic cause in these families. Three mutations were found in VPS13B gene. The detected mutations were c.4608_4609del (p.E1537Rfs*7), c.11486dupG (p.L3830Tfs*13), and c.10360dupC (p.L3454fs*7). The current study broadens the mutation spectrum of VPS13B gene and demonstrates different phenotypic features from classic Cohen syndrome. Moreover, the provided data can be used in genetic counseling and prenatal diagnosis of Iranian patients.

ELMO Domain Containing 1 (ELMOD1) Gene Mutation Is Associated with Mental Retardation and Autism Spectrum Disorder.

ELMO domain containing 1 (ELMOD1) encodes a protein with GTPase-activating functions. Previous studies have confirmed its overexpression in brain tissues. Although no previous study has reported mutations in this gene in human subjects, spontaneous inactivating mutations in the mouse homolog of this gene have been associated with deafness and balance problems. In the current study, we have performed whole exome sequencing (WES) in a patient with intellectual disability. We found a novel mutation in ELMOD1 gene (c.571delG, p.D191MfsTer25) in the proband and two other affected cases in the family. Segregation analysis showed that parents carried the mutation in the heterozygote state. Consequently, the current study reports the first case of mutation in ELMOD1 in human subjects and demonstrates the significant difference in the phenotypes associated with ELMOD1 mutations in humans and mice.

A Novel Nonsense Mutation in PANK2 Gene in Two Patients with Pantothenate Kinase-Associated Neurodegeneration.

Pantothenate kinase- associated neurodegeneration (PKAN) syndrome is a rare autosomal recessive disorder characterized by progressive extrapyramidal dysfunction and iron accumulation in the brain and axonal spheroids in the central nervous system. It has been shown that the disorder is caused by mutations in PANK2 gene which codes for a mitochondrial enzyme participating in coenzyme A biosynthesis. Here we report two cases of classic PKAN syndrome with early onset of neurodegenerative disorder. Mutational analysis has revealed that both are homozygous for a novel nonsense mutation in PANK2 gene (c.T936A (p.C312X)). The high prevalence of consanguineous marriages in Iran raises the likelihood of occurrence of autosomal recessive disorders such as PKAN and necessitates proper premarital genetic counseling. Further research is needed to provide the data on the prevalence of PKAN and identification of common PANK2 mutations in Iranian population.