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Jeune asphyxiating thoracic dystrophy (JATD; Jeune syndrome, MIM 208500) is a rare autosomal recessive chondrodysplasia, phenotypically overlapping with short-rib polydactyly syndromes (SRPS). JATD typical hallmarks include skeletal abnormalities such as narrow chest, shortened ribs, limbs shortened bones, extra fingers and toes (polydactyly), as well as extraskeletal manifestations (renal, liver and retinal disease). To date, disease-causing mutations have been found in several genes, highlighting a marked genetic heterogeneity that prevents a molecular diagnosis of the disease in most families. Here, we report the results of whole-exome sequencing (WES) carried out in four JATD cases, belonging to three unrelated families of Sardinian origin. The exome analysis allowed to identify mutations not previously reported in the DYNC2H1 (MIM 603297) and WDR60 (MIM 615462) genes, both codifying for ciliary intraflagellar transport components whose mutations are known to cause Jeune syndrome., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Allan-Herndon-Dudley syndrome (AHDS), an X linked condition, is characterized by severe intellectual disability, dysarthria, athetoid movements, muscle hypoplasia and spastic paraplegia in combination with altered TH levels, in particular, high serum T3 levels. Mutations in the MCT8 gene coding for the monocarboxylate thyroid hormone transporter 8 have been associated with AHDS. Here we describe a family with the presence of a MCT8 gene mutation, p.A224T, in three consecutive generations. In two generations its presence was detected in the hemizygous state in two males with neurological abnormalities including mental retardation, axial hypotonia, hypertonia of arms and legs and athetoid movements. One of them presented normal thyroid hormone levels. Mutation was also detected, although in the heterozygous state, in three females showing thyroid hormone levels in the normal range. Our results show the difficulty of distinguishing AHDS from patients with X-linked intellectual disability solely on the basis of clinical features and biochemical tests, and we advise screening for MCT8 mutations in either young or older patients with severe intellectual disability, axial hypotonia/dystonia, poor head control, spastic paraplegia, and athetoid movements even when they have normal thyroid hormone profiles., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Thyroid hormones are known to be essential for growth, development and metabolism. Recently mutations in the SLC16A2 gene coding for the monocarboxylate thyroid hormone transporter 8, MCT8, have been associated with Allan-Herndon-Dudley syndrome (AHDS), an X-linked condition characterized by severe mental retardation, dysarthria, athetoid movements, muscle hypoplasia and spastic paraplegia. Here we describe in detail the clinical and biochemical features in a boy affected by AHDS with severe neurological abnormalities and a novel de novo SLC16A2 gene insertion, 1343-1344insGCCC, resulting in a truncated protein lacking the last four transmembrane domains (TMDs) as well as the carboxyl cytoplasmic end. He presents mental retardation, axial hypotonia, hypertonia of arms and legs, paroxysmal dyskinesias, seizures. The endocrine phenotype showed low serum total and free thyroxine (T4), very elevated total and free triiodothyronine (T3) and normal thyrotropin (TSH) with blunted response to thyrotropin-releasing hormone (TRH). The latter finding was unexpected and suggested that the lack of functional MCT8 was counterbalanced at the thyrotrope cell level by high serum T3 concentration and/or by increased intrapituitary type 2 deiodinase (D2) activity. Our case constitutes a relevant contribution to better characterize this disorder and to elucidate the functional consequences of SLC16A2 gene mutations., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

The CACNA1A gene codes for the alpha(1A) pore-forming subunit of Ca(2+) voltage-gated Cav2.1 channels. CACNA1A mutations are responsible for Familial Hemiplegic Migraine (FHM) type 1, Episodic Ataxia (EA) type 2 and Spinocerebellar Ataxia type 6. The structure of the human gene includes, at present, 49 exons; however almost nothing is known about the 5' regulatory region, and there is now evidence suggesting the presence of additional exons at the 3' of the gene. The 892 bp fragment upstream of exon 1 and its deletion mutants were characterised for their transcriptional activity by using luciferase as a reporter gene. The 3' region was analysed by Rapid Amplification of the cDNA 3' End. Both regions were screened for mutations in a series of FHM and EA patients by SSCP and sequencing. At the 5' end of the gene a minimal promoter region was identified within the first 497 bp from ATG. By screening a larger fragment for mutations, the 5 bp deletion (g.-757_-753delCTTTC) was identified in a FHM patient. The deletion significantly increased the transcriptional activity, most likely due to the removal of half a turn of the DNA helix, changing the orientation of downstream binding sites for transcriptional factors. At the 3' end of the gene a new exon 48, followed by a strong poly-A signal, was identified as well as a new splice variant. The 5 bp insertion (g.38429_38430insCTTTT) in this exon was found in an EA patient. The two new regions can open the way for the study of human CACNA1A gene expression regulation and can be sites of mutations associated with FHM or EA phenotypes.