Activation of mitogen-activated protein kinase signaling and development of papillary thyroid carcinoma in thyroid-stimulating hormone receptor D633H knockin mice

Objective

Nonautoimmune hyperthyroidism (NAH) is rare and occurs due to a constitutively activating thyroid stimulating hormone receptor (TSHR) mutation. In contrast to other thyroid nodules, no further evaluation for malignancy is recommended for hot thyroid nodules. In the first model for NAH in mice nearly all homozygous mice had developed papillary thyroid cancer by 12 months of age.

Methods

To further evaluate these mice, whole exome sequencing and phosphoproteome analysis were employed in a further generation of mice to identify any other mutations potentially responsible and to identify the pathways involved in thyroid carcinoma development.

Results

Only three genes (Nrg1, Rrs1, Rasal2) were mutated in all mice examined, none of which were known primary drivers of papillary thyroid cancer development. Wild-type and homozygous TSHR D633H knockin mice showed distinct phosphoproteome profiles with an enrichment of altered phosphosites found in ERK/mitogen-activated protein kinase (MAPK) signaling. Most importantly, phosphosites with known downstream effects included BRAF p.S766, which forms an inhibitory site: a decrease of phosphorylation at this site suggests an increase in MEK/ERK pathway activation. The decreased phosphorylation at BRAF p.S766 would suggest decreased AMP-activated protein kinase (AMPK) signaling, which is supported by the decreased phosphorylation of STIM1 p.S257, a downstream AMPK target.

Conclusion

The modified phosphoproteome profile of the homozygous mice in combination with human literature suggests a potential signaling pathway from constitutive TSHR signaling and cAMP activation to the activation of ERK/MAPK signaling. This is the first time that a specific mechanism has been identified for a possible involvement of TSH signaling in thyroid carcinoma development.

Validation of the virtual measurement of the Essential Frailty Toolset

Funding Acknowledgements

Type of funding sources: None.

Background

The Essential Frailty Toolset (EFT) is a valid measurement of frailty in people with heart valve disease. COVID-19 has prompted the transition to virtual health consultations and necessitates the validation of the virtual assessment of frailty.

Methods

We conducted a prospective observational cohort study to compare the measurement of EFT in person and virtual format within a maximum 2-week window of repeated measurement. The weighted Kappa tests was used to measure the agreement of EFT scores between assessments; we explored the effect of the sequence of measurement using the Cochran-Mantel-Haenszel statistic to test the general association between the timing of measurement and differences of EFT score.

Results

We recruited a sample of 49 patients, with a mean age of 81 ± 7 years, including 29 men (59.2%); the primary valvular heart diseases were aortic stenosis (n=40, 81.6%), mitral regurgitation (n=2, 4.1%) and tricuspid regurgitation (n=7, 14.3%). The virtual measurement of frailty was conducted using a standardised protocol. The platform for virtual connection selected by patients was FaceTime (n=20, 40.8%) and Zoom (n=29, 59.2%); the median (IQR) number of days between the in-person and the virtual assessment was 5 (3,10). The weighted Kappa estimate was 0.69 (95% CI 0.55, 0.82), illustrating a strong agreement between the separate scores obtained. The test for the general association was non-significant (p=0.82), indicating a lack of evidence for detecting an association between EFT scores and chronological order of assessment.

Conclusion

The EFT can be reliably measured virtual in older patients with valvular heart disease to inform clinical care.

Implementation of nurse-led early mobilisation after transcatheter aortic valve implantation: Identification of barriers to standardised practice

Funding Acknowledgements

Type of funding sources: None.

Background

We examined the barriers of early nurse-led mobilisation after transcatheter aortic valve implantation (TAVI) to support safe next-day discharge home.

Methods

We conducted a prospective observational cohort study of patients treated in 2019-2021 using a standardised post-procedure nursing care standard to promote mobilisation in 4 to 6 hours after TAVI. Results are presented as mean (standard deviation) for continuous variables and as number (percentage) for categorical data; student t test was used to compare continuous variables and χ2 and Fisher exact tests were used to compare categorical variables. All analyses were performed in SAS version 9.4 (SAS Institute).

Results

The cohort included a convenience sample of 139 patients (64 women, 46%) mean age 82.5±6.7 years, NYHA III/IV 72 (51.8%), prior pacemaker 18 (13%), and prior SAVR 11 (7.9%). Patients were treated under local anaesthesia only (n=29, 20.9%) or conscious sedation (n=106, 76.3%) with a balloon expandable device (n=134, 96.4%) in a cardiac catheterisation laboratory (n=111, 79.9%) or hybrid operating room (n=28, 25.2%), and early recovery in cardiac telemetry (n=101, 72.7%) or critical care unit (n=38, 27.3%). Early mobilisation was achieved in 113 patients (81.3%: 4 hours: n=100, 71.9%, 4-6 hours: n=13, 9.4%); there were no significant (p≤0.05) differences in baseline characteristics between patients with early vs. late mobilisation; the primary reasons for delayed mobilisation included monitoring and/or managing cardiac conduction issues (n=6), vascular access hemostasis (n=6) and neurological status (n=4), patient preference or other self-reported issue (n=5) and nursing workload (n=5). In patients who achieved early mobilisation, 81.4% were discharge on post-operative day 1 and 86.3% by day 2, with 99.1% returning directly home. There was no significant difference in 30-day readmission between the two groups.

Conclusions

Early nurse-led protocol-driven mobilisation is safe and effective to facilitate rapid reconditioning and safe transition home after uncomplicated TAVI. Research is needed to better understand patient and systems-level enablers to improve standardisation of practice.

Report of a family with three generations of undiagnosed familial nonautoimmune hyperthyroidism

SUMMARY

Familial nonautoimmune hyperthyroidism (FNAH) is rare and occurs due to a constitutively activating thyroid-stimulating hormone receptor (TSHR) germline mutation. Forty-one families with FNAH have been reported so far. In the study, 17 of 41 families were not diagnosed with FNAH until three generations or more were described with hyperthyroidism. We report a case of FNAH diagnosed in the third generation. The index patient was diagnosed with hyperthyroidism at age 3. Large fluctuations in thyroid hormone levels occurred during anti-thyroid drug treatment, and he developed a goiter. The patient's mother had similar history, requiring two surgical interventions and radioiodine treatment. The younger brother of the index patient did not experience large thyroid hormone level fluctuations, nor increased thyroid growth. A heterozygous TSHR c.1357A>G mutation, resulting in a M453V amino acid exchange, was detected in all three patients leading to FNAH diagnosis, with complete genotype-phenotype segregation. Based on Sorting intolerant from tolerant (SIFT) and PolyPhen2 scores of 0.01 and 0.99, respectively, an effect on protein function can be assumed. As illustrated by this family with FNAH, total thyr oidectomy is necessary for patients with nonautoimmune hyperthyroidism. Development of goiter is common, anti-thyroid drug treatment is often difficult, and remission of hyperthyroidism does not occur after discontinuation of anti-thyroid drug treatment. Thus, early diagnosis and appropriate treatment of FNAH is necessary to avoid predictable, unnecessary complications and further surgical interventions.

LEARNING POINTS

In the study, 19/42 cases of familial nonautoimmune hyperthyroidism (FNAH), including the reported case, were not diagnosed as FNAH until the third generation; this lead to suboptimal treatment and frequent relapses of nonautoimmune hyperthyroidism (NAH). Detection of thyroid-stimulating hormone receptor (TSHR) mutations in patients with suspected FNAH to confirm diagnosis is essential to ensure proper treatment for the patient and further affected family members. NAH will persist without proper treatment by total thyroidectomy. Symptoms and age of onset may vary between family members All family members with a TSHR germline mutation should be monitored with thyroid-stimulating hormone and for symptoms throughout their lives.

Malignancy risk of hyperfunctioning thyroid nodules compared with non-toxic nodules: systematic review and a meta-analysis

Background

Hyperfunctioning or hot nodules are thought to be rarely malignant. As such, current guidelines recommend that hot nodules be excluded from further malignancy risk stratification. The objective of this systematic review and meta-analysis is to compare the malignancy risk in hot nodules and non-toxic nodules in observational studies.

Methods

Ovid MEDLINE Daily and Ovid MEDLINE, EMBASE, Scopus, and Web of Science databases were searched. Observational studies which met all of the following were included: (1) use thyroid scintigraphy for nodule assessment, (2) inclusion of both hyperfunctioning and non-functioning nodules based on scintigraphy, (3) available postoperative histopathologic nodule results, (4) published up to November 12, 2020 in either English or French. The following data was extracted: malignancy outcomes include malignancy rate, mapping of the carcinoma within the hot nodule, inclusion of microcarcinomas, and presence of gene mutations.

Results

Among the seven included studies, overall incidence of malignancy in all hot thyroid nodules ranged from 5 to 100% in comparison with non-toxic nodules, 3.8–46%. Odds of malignancy were also compared between hot and non-toxic thyroid nodules, separated into solitary nodules, multiple nodules and combination of the two. Pooled odds ratio (OR) of solitary thyroid nodules revealed a single hot nodule OR of 0.38 (95% confidence interval (CI) 0.25, 0.59), toxic multinodular goiter OR of 0.51 (95% CI 0.34, 0.75), and a combined hot nodule OR of 0.45 (95% CI 0.31, 0.65). The odds of malignancy are reduced by 55% in hot nodules; however, the incidence was not zero.

Conclusions

Odds of malignancy of hot nodules is reduced compared with non-toxic nodules; however, the incidence of malignancy reported in hot nodules was higher than expected. These findings highlight the need for further studies into the malignancy risk of hot nodules.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13044-021-00094-1.

Sensitive Sequencing Analysis Suggests Thyrotropin Receptor and Guanine Nucleotide-Binding Protein G Subunit Alpha as Sole Driver Mutations in Hot Thyroid Nodules

Background: Constitutively activating mutations in the thyrotropin receptor (TSHR) and the guanine nucleotide-binding protein G subunit alpha (GNAS) are the primary cause of hot thyroid nodules (HTNs). The reported prevalence of TSHR and GNAS mutations in HTNs varies. Previous studies show TSHR mutations in 8-82% of HTNs and GNAS mutations in 8-75% of HTNs. With sensitive and comprehensive targeted next-generation sequencing (tNGS), we re-evaluated the prevalence of TSHR and GNAS mutations in HTNs. Methods: Samples from three previous studies found to be TSHR and GNAS mutation negative were selected and re-evaluated using high-resolution melting (HRM) PCR. Remaining mutation negative samples were further reanalyzed by tNGS with a sequencing depth between 3000 × and 10,000 × . Our tNGS panel covered the entire TSHR coding sequence along with mutation hot spots in GNAS. Sequencing reads were aligned to reference and variants were called using Torrent Suite software v5.8. Results: In total, 154 of 182 previously mutation negative HTNs were positive for TSHR or GNAS mutations, resulting in an 85% prevalence of TSHR and GNAS mutations in HTNs, 79% and 6%, respectively. In a subset of 25 HTNs with multiple samples per nodule, and analyzed by tNGS at high sequencing depth, TSHR mutations were detected in 23 (92%) HTNs and 1 GNAS mutation was detected in 1 (4%) HTN, 96% mutation positive HTNs in this subset. Conclusions: Owing to the higher sensitivity of tNGS as compared with denaturing gradient gel electrophoresis and HRM-PCR, TSHR or GNAS mutations could be detected in 85% of HTNs. The detection of TSHR and GNAS mutations occurred in 96% of HTNs in a sample set with multiple samples per nodule analyzed by tNGS. Taken together with the fact that no other driver mutations could be identified by whole exome sequencing, our study strongly supports the hypothesis that TSHR and GNAS mutations are the main somatic mutations leading to HTNs.

The Thyrotropin Receptor Mutation Database Update

The thyrotropin receptor (TSHR) mutation database, consisting of all known TSHR mutations and their clinical characterizations, was established in 1999. The database contents are updated here with the same website (tsh-receptor-mutation-database.org). The new database contains 638 cases of TSHR mutations: 448 cases of gain of function mutations (7 novel mutations and 41 new cases for previously described mutations since its last update in 2012) and 190 cases of loss of function mutations (28 novel mutations and 31 new cases for previously described mutations since its last update in 2012). This database is continuously updated and allows for rapid validation of patient TSHR mutations causing hyper- or hypothyroidism or insensitivity to TSH.

Long-term survival of pig-to-rhesus macaque renal xenografts is dependent on CD4 T cell depletion

The shortage of available organs remains the greatest barrier to expanding access to transplant. Despite advances in genetic editing and immunosuppression, survival in experimental models of kidney xenotransplant has generally been limited to <100 days. We found that pretransplant selection of recipients with low titers of anti-pig antibodies significantly improved survival in a pig-to-rhesus macaque kidney transplant model (6 days vs median survival time 235 days). Immunosuppression included transient pan-T cell depletion and an anti-CD154-based maintenance regimen. Selective depletion of CD4⁺ T cells but not CD8⁺ T cells resulted in long-term survival (median survival time >400 days vs 6 days). These studies suggested that CD4⁺ T cells may have a more prominent role in xenograft rejection compared with CD8⁺ T cells. Although animals that received selective depletion of CD8⁺ T cells showed signs of early cellular rejection (marked CD4⁺ infiltrates), animals receiving selective CD4⁺ depletion exhibited normal biopsy results until late, when signs of chronic antibody rejection were present. In vitro study results suggested that rhesus CD4⁺ T cells required the presence of SLA class II to mount an effective proliferative response. The combination of low pretransplant anti-pig antibody and CD4 depletion resulted in consistent, long-term xenograft survival.

An update on the screening, diagnosis, management, and treatment of vitamin D deficiency in individuals with cystic fibrosis: evidence-based recommendations from the Cystic Fibrosis Foundation

OBJECTIVE

The objective was to develop evidence-based clinical care guidelines for the screening, diagnosis, management, and treatment of vitamin D deficiency in individuals with cystic fibrosis (CF).

PARTICIPANTS

The guidelines committee was comprised of physicians, registered dietitians, a pharmacist, a nurse, a parent of an individual with CF, and a health scientist, all with experience in CF.

PROCESS

Committee members developed questions specific to vitamin D health in individuals with CF. Systematic reviews were completed for each question. The committee reviewed and graded the available evidence and developed evidence-based recommendations and consensus recommendations when insufficient evidence was available. Each consensus recommendation was voted upon by an anonymous process.

CONCLUSIONS

Vitamin D deficiency is common in CF. Given the limited evidence specific to CF, the committee provided consensus recommendations for most of the recommendations. The committee recommends yearly screening for vitamin D status, preferably at the end of winter, using the serum 25-hydroxyvitamin D measurement, with a minimal 25-hydroxyvitamin D concentration of 30 ng/ml (75 nmol/liter) considered vitamin D sufficient in individuals with CF. Recommendations for age-specific vitamin D intake for all individuals with CF, form of vitamin D, and a stepwise approach to increase vitamin D intake when optimal vitamin D status is not achieved are delineated.

Understanding the population structure of North American patients with cystic fibrosis

It is generally presumed that the cystic fibrosis (CF) population is relatively homogeneous, and predominantly of European origin. The complex ethnic make-up observed in the CF patients collected by the North American CF Modifier Gene Consortium has brought this assumption into question, and suggested the potential for population substructure in the three CF study samples collected from North America. It is well appreciated that population substructure can result in spurious genetic associations. To understand the ethnic composition of the North American CF population, and to assess the need for population structure adjustment in genetic association studies with North American CF patients, genome-wide single-nucleotide polymorphisms on 3076 unrelated North American CF patients were used to perform population structure analyses. We compared self-reported ethnicity to genotype-inferred ancestry, and also examined whether geographic distribution and cystic fibrosis transmembrane regulator (CFTR) mutation type could explain the population structure observed. Although largely Caucasian, our analyses identified a considerable number of CF patients with admixed African-Caucasian, Mexican-Caucasian and Indian-Caucasian ancestries. Population substructure was present and comparable across the three studies of the consortium. Neither geographic distribution nor CFTR mutation type explained the population structure. Given the ethnic diversity of the North American CF population, it is essential to carefully detect, estimate and adjust for population substructure to guard against potential spurious findings in CF genetic association studies. Other Mendelian diseases that are presumed to predominantly affect single ethnic groups may also benefit from careful analysis of population structure.

Sunitinib in patients (pts) with unresectable primary renal cell carcinoma (RCC)

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Background: Sunitinib inhibits VEGF and related receptors, with high tumor shrinkage rates in metastatic (met) RCC. Shrinkage of primary tumors has been observed, although prospective investigation is lacking. The ability of sunitinib to convert primary RCC tumors from unresectable to resectable is of high clinical interest. Methods: Pts with histologically-confirmed RCC with an unresectable primary tumor with or without met disease were enrolled on a single-arm phase II trial. Primary tumors were unresectable due to ≥ 1 of the following: large tumor size, bulky lymphadenopathy, encasement of renal vessels, IVC thrombosis or proximity to vital structures. Pts received 50 mg sunitinib continuous dosing in repeated 6-week cycles. Staging by CT scans or MRI was done at baseline and every 2 cycles. A Simon 2-stage design was employed to test the alternative hypothesis of a conversion to resectability rate of 20% versus the null hypothesis of 5%; β = 0.8, α = 0.05 (n = 31). Results: 18 pts have been enrolled; 1 excluded due to a non-RCC diagnosis. Pts were unresectable due to bulky lymphadenopathy (6), IVC thrombosis (4), proximity to vital structures (4) or tumor size (3), although most pts had multiple factors. Median age among 14 evaluable pts was 61 years (range, 37–80), 59% male, 76% ECOG PS 0; 79% had distant met disease. The 14 evaluable pts have received a median of 3 cycles of therapy (range, 1–10+). Three pts (21%) have undergone primary tumor resection; viable RCC was identified in all specimens with no unexpected surgical morbidity. Nine pts (53%) had primary tumor reduction (median 19%; range, -64% to -1%). Overall, median best % change in tumor burden was 4.9% reduction for primary tumors (range, -43.1% to +8.5%) and 10.7% reduction for met sites (range, -89.5% to +28.6%). Median PFS is 4.9 months. Eleven pts (79%) discontinued therapy; 8 for PD, 1 for adverse events and 2 following surgery which removed all visible disease. Eight pts (57%) experienced grade 3 toxicity including thrombocytopenia, fatigue, hypertension, anemia, hemoptysis, and hand-foot syndrome; 1 pt had grade 4 neutropenia. Conclusions: Sunitinib has activity in unresectable primary RCC tumors, permitting resection in some pts. Continued prospective investigation is required to optimize patient selection and timing of surgery.

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Micropapillary urothelial carcinoma of the urinary bladder: Early surgery or neoadjuvant chemotherapy?

e16007

Background: Micropapillary bladder carcinoma is a rare variant of urothelial carcinoma (UC) of the urinary bladder. As a particularly aggressive variant, patients are often urged to undergo up-front radical cystectomy. Though data is scarce on the treatment outcomes of patients with this entity, we present the case for neoadjuvant chemotherapy as opposed to early cystectomy in the setting of clinically localized micropapillary UC. Methods: A review of records of all patients evaluated at our institution for UC was conducted to identify micropapillary UC of the bladder over the period from 2000–2007. A total of 24 cases were found, and were evaluated for preoperative pathology and clinical stage, treatment course, pathological stage and cancer specific survival. Results: Mean patient age was 67.9 years with 19 males and 5 females. Twenty-one (87.5%) patients had clinically organ confined micropapillary UC at the time of diagnosis, three had minimally enlarged lymph nodes on pelvic CAT scans. Half of our patients had BCG refractory high grade non-muscle invasive UC. Twenty-two patients (91.67%) were offered radical cystectomy as first line management. Extended lymph node dissection was performed in eleven patients (45.83%). Final pathologic examination diagnosed metastatic lymph node involvement in 20 patients (83.33%), with 4 patients (20%) having positive LN outside the standard (pelvic) template of dissection. A stage upgrade was noticed in 95.23% of cases. Median cancer specific survival was 13 months. Survival at one year was 44% and 50% at 2years, with only one patient alive at 5 years. Conclusions: Our results suggest that clinically localized micropapillary UC is often metastatic to LN at the time of presentation. This setting of frequent systemic disease should encourage standard neoadjuvant chemotherapy rather than early surgical management for these patients. Extended LN dissection is warranted in these cases due to the high incidence of nodal involvement outside the standard template.

No significant financial relationships to disclose.

Effect of endotoxin on oleic acid lung injury does not depend on priming

Recent studies have demonstrated significant synergistic physiological and biochemical effects between low-dose endotoxin (Etx) administration and oleic acid (OA)-induced canine lung injury. To evaluate whether this interaction depends on Etx priming of some key cell population, we compared the effects of giving low-dose Etx both after as well as before inducing lung injury with OA. In addition to hemodynamic and blood-gas measurements, positron emission tomographic imaging was used to measure edema accumulation and intrapulmonary blood flow distribution. Biochemical measurements of the stable metabolites of prostacyclin and thromboxane were obtained as well as measurements of isoprostanes and reactive sulfhydryls as evidence for possible concomitant oxidant production. We found that the physiological and biochemical effects of low-dose Etx developed 30-45 min after its administration, regardless of whether Etx was administered before or after OA. No increase in either isoprostane or reactive sulfhydryl production after Etx and/or OA was detected. These data suggest that the synergistic effect of low-dose Etx and OA-induced lung injury is not due to a priming effect of Etx.

Metals in tissues of European otters (Lutra lutra) from Denmark, Great Britain and Ireland

Samples of livers of European otters from Denmark, Great Britain and Ireland were analyzed for manganese, chromium, zinc, copper, nickel and cobalt. Concentrations were generally significantly higher in samples from Great Britain. It was considered that this reflected the catchment geology from where the specimens originated.

Teaching professional development in medical schools

Doctors must increasingly be aware of what they should be, as well as what they should know. Professionalism, including a value system that supports the compassionate care of patients, is a means of encapsulating and prioritising these competing responsibilities. Accordingly, in this article, we assume that professionalism is an essential aspect of medical practice that needs to be taught to those entering medicine. We first describe critiques of professionalism and current challenges to it, in practice and in medical education. We then assess the current efforts of curriculum reform to incorporate professionalism and the methods used to teach it. Adopting and assessing such approaches to ensure that they are effective is of central importance in the education of future clinicians.

Superior epithelial arcuate lesions with soft contact lens wear

BACKGROUND

Superior epithelial arcuate lesions (SEALs) are an infrequent and often asymptomatic complication of conventional soft contact lens wear. The characteristic arcuate pattern of the full-thickness corneal epithelial lesion usually occurs in the area covered by the upper eyelid, within 2 to 3 mm of the superior limbus in the 10- and 2-o'clock region.

METHODS

Literature on SEALs and recent clinical records from clinical trials using two types of prototype high Dk soft contact lenses were reviewed to gain greater insights into the etiology of SEALs.

RESULTS AND CONCLUSIONS

The reported low incidence of SEALs is partly because SEALs are not usually symptomatic. The etiology of SEALs is multifactorial. Our current hypothesis is that SEALs are produced by mechanical chaffing at the peripheral cornea. This chaffing occurs as a result of inward pressure of the upper lid, in an area where the peripheral corneal topography and lens design, rigidity, and surface characteristics combine to create excessive "frictional" pressure and abrasive shear force on the epithelial surface. Patient characteristics such as gender, age, and specific corneal and lid topographies also appear to influence the occurrence of SEALs. Prototype silicone hydrogel lenses are made from higher modulus materials with surfaces that seem to differ subtly in wettability in some patients. The prevalence of SEALs may well increase with the first generations of these lenses.

The relationship of genotype to cognitive outcome in galactosaemia

AIMS

To evaluate the cognitive outcome of a cohort of children with galactosaemia in relation to genotype.

METHODS

The cohort was drawn from children notified to the British Paediatric Surveillance Unit galactosaemia study which ran from 1988 to 1990. Cognitive outcome was assessed using the Wechsler Intelligence Scale for Children or the Wechsler Preschool and Primary Scale of Intelligence. Parents completed a questionnaire detailing educational status, and the attending paediatrician returned a questionnaire regarding age at diagnosis and biochemical outcome over the previous two years.

RESULTS

A total of 45 children were genotyped: 30 were homoallelic for the Q188R mutation, the remainder being heteroallelic for Q188R with K285N (n = 4), L195P (n = 4), or other mutations (n = 7). Psychometric evaluation was available in 34 cases: mean full scale IQ was 79, verbal quotient 79, and performance quotient 82. Genotype was not related to galactose-1-phosphate (Gal-1-P) concentrations. However, children homoallelic for the Q188R mutation had significantly lower IQ scores than those who were heteroallelic (73. 6 v 94.8). This difference was independent of social and demographic influences and Gal-1-P concentrations over the previous two years.

CONCLUSIONS

In children with galactosaemia, cognitive outcome appears to relate to genotype rather than metabolic control, as reflected by Gal-1-P concentrations. The value of measuring Gal-1-P concentrations routinely once successfully established on a galactosaemia diet is questionable as concentrations do not appear to affect outcome. In the UK population, homozygosity for the Q188R mutation is invariably associated with a poor outcome, and there is evidence that variability in neurocognitive outcome is at least part dependent on allelic heterogeneity.