Molecular characterisation of benign and malignant thyroid dysfunction

Nodular thyroid disease is common (prevalence 2-6%) and is a significant risk factor for the development of thyroid cancer. My aim was to apply genome-wide- linkage-analysis to identify the defect in a large kindred with multi-nodular goitre (MNG) of adolescent onset progressing to papillary thyroid cancer (PTC). Genomic DNA from 18 individuals (8 affected) was hybridized to Affymetrix GeneChip® Human Mapping 10K 2.0 Arrays. Results were analysed with Affymetrix GTYPE software to produce a call rate of ~92%. Extensive quality control steps were performed (PLINK, GRR) prior to linkage analysis using Merlin software in multipoint non-parametric and parametric (dominant) model. A non-parametric LOD score of 3.01 was obtained on chromosome 20 across 20cM, the same region produced a dominant LOD score of 2.03. Haplotype analysis reduced the region of interest to 3.7 Mbp, (encodes 10 genes). Analysis of copy number variation in an affected individual (Illumina Human 660W-Quad) revealed an intronic deletion of ~1000 bp in one copy of Phospholipase-C β1 (PLCβ1), (the first in the 10 gene list), which is present in all affected family members and carriers. The deletion contained ‘ATAA’ at the junction site and this InDel was found in 1 of 105 healthy unrelated people, a similar variant was reported in the database of genomic variants in ~1% of Europeans . The deletion was not present in 70 unrelated PTC patients but was found in 4/81 with MNG (all European); the deletion frequency in the general population vs. MNG gives a X2 value of 5.076 (p=0.024). PLCβ1 expression was measured in thyroid tissues from affected family members and subjects free of the InDel and were significantly higher in the former (p< 0.02). In conclusion, the InDel identified in familial MNG occurs in a proportion of sporadic MNG. It predisposes to goitre formation, possibly by increasing PLCβ1 transcription and activating the diacyl-glycerol, PKC and MAPK pathways

An InDel in Phospholipase-C-B-1 is linked with euthyroid multinodular goiter

Background: Euthyroid multinodular goiter (MNG) is common, but little is known about the genetic variations conferring predisposition. Previously, a family with MNG of adolescent onset was reported in which some family members developed papillary thyroid carcinomas (PTC). Methods: Genome-wide linkage analysis and next-generation sequencing were conducted to identify genetic variants that may confer disease predisposition. A multipoint nonparametric LOD score of 3.01 was obtained, covering 19 cM on chromosome 20p. Haplotype analysis reduced the region of interest to 10 cM. Results: Analysis of copy number variation identified an intronic InDel (∼1000 bp) in the PLCB1 gene in all eight affected family members and carriers (an unaffected person who has inherited the genetic trait). This InDel is present in approximately 1% of “healthy” Caucasians. Next-generation sequencing of the region identified no additional disease-associated variant, suggesting a possible role of the InDel. Since PLCB1 contributes to thyrocyte growth regulation, the InDel was investigated in relevant Caucasian cohorts. It was detected in 0/70 PTC but 4/81 unrelated subjects with MNG (three females; age at thyroidectomy 27–59 years; no family history of MNG/PTC). The InDel frequency is significantly higher in MNG subjects compared to controls (χ2 = 5.076; p = 0.024. PLCB1 transcript levels were significantly higher in thyroids with the InDel than without (p < 0.02). Conclusions: The intronic PLCB1 InDel is the first variant found in familial multiple papilloid adenomata-type MNG and in a subset of patients with sporadic MNG. It may function through overexpression, and increased PLC activity has been reported in thyroid neoplasms. The potential role of the deletion as a biomarker to identify MNG patients more likely to progress to PTC merits exploration

A new form of familial multi-nodular goitre with progression to differentiated thyroid cancer

We report a kindred with euthyroid multi-nodular goitre (MNG) of adolescent onset. Two of the seven subjects with MNG have progressed to papillary thyroid cancer. One affected male had nodular kidney disease, and breast cancer occurred in one affected female. Genes that were candidates on the basis of the associated kidney (PAX8) and breast diseases (sodium iodide symporter (NIS)), were sequenced. No mutations were found in the coding region, intron/exon splice sites or in the promoter sequences (from −1248 relative to the translation initiation codon) of PAX8. Similar results were obtained for NIS. Subsequently, microsatellite analyses were performed on 14 informative family members. We used 2 to 3 markers per locus for 6 loci (on chromosomes 1,2,3,14,19,X) previously reported to predispose to MNG and/or familial non-medullary thyroid cancer (FNMTC). On the basis of non-significant logarithm of the odds ratio (LOD) scores or inheritance of different alleles in affected individuals, all loci have been excluded. Thyroidectomy specimens from three members of the kindred show multiple benign lesions, with papillary cancer in two. The morphological features do not resemble those seen in familial adenomatous polyposis, Cowden syndrome, or in multiple oxyphil lesions. From these findings and from the absence of any linkage to any of the known loci associated with MNG or FNMTC, we suggest that this represents a new form of inherited MNG with a significant risk of progression to papillary carcinoma

Controlled antenatal thyroid screening II: Effect of treating maternal suboptimal thyroid function on child cognition.

Context and Objective The Controlled Antenatal Thyroid Screening (CATS) study investigated treatment of suboptimal gestational thyroid function (SGTF) on childhood cognition and found no difference in intelligence quotient (IQ) at 3 years between children of treated and untreated SGTF mothers. We have measured IQ in the same children at age 9.5 years and included children from normal gestational thyroid function (normal-GTF) mothers. Design, Setting, and Participants One examiner, blinded to participant group, assessed children’s IQ (Wechsler Intelligence Scale for Children, Fourth Edition UK), long-term memory, and motor function (Developmental Neuropsychological Assessment II) from children of 119 treated and 98 untreated SGTF mothers plus children of 232 mothers with normal-GTF. Logistic regression explored the odds and percentages of an IQ 97.5th percentile of the entire CATS-I cohort revealed no significant effect on a child’s IQ < 85 in CATS-II. IQ at age 3 predicted IQ at age 9.5 (P < 0.0001) and accounted for 45% of the variation. Conclusions Maternal thyroxine during pregnancy did not improve child cognition at age 9.5 years. Our findings confirmed CATS-I and suggest that the lack of treatment effect may be a result of the similar proportion of IQ < 85 in children of women with normal-GTF and SGTF.N/