High- and intermediate-risk susceptibility variants in melanoma families from the Mediterranean area: A multicentre cohort from the MelaNostrum Consortium.

BACKGROUND: Most of large epidemiological studies on melanoma susceptibility have been conducted on fair skinned individuals (US, Australia and Northern Europe), while Southern European populations, characterized by high UV exposure and dark-skinned individuals, are underrepresented. OBJECTIVES: We report a comprehensive pooled analysis of established high- and intermediate-penetrance genetic variants and clinical characteristics of Mediterranean melanoma families from the MelaNostrum Consortium. METHODS: Pooled epidemiological, clinical and genetic (CDKN2A, CDK4, ACD, BAP1, POT1, TERT, and TERF2IP and MC1R genes) retrospective data of melanoma families, collected within the MelaNostrum Consortium in Greece, Italy and Spain, were analysed. Univariate methods and multivariate logistic regression models were used to evaluate the association of variants with characteristics of families and of affected and unaffected family members. Subgroup analysis was performed for each country. RESULTS: We included 839 families (1365 affected members and 2123 unaffected individuals). Pathogenic/likely pathogenic CDKN2A variants were identified in 13.8% of families. The strongest predictors of melanoma were ≥2 multiple primary melanoma cases (OR 8.1; 95% CI 3.3-19.7), >3 affected members (OR 2.6; 95% CI 1.3-5.2) and occurrence of pancreatic cancer (OR 4.8; 95% CI 2.4-9.4) in the family (AUC 0.76, 95% CI 0.71-0.82). We observed low frequency variants in POT1 (3.8%), TERF2IP (2.5%), ACD (0.8%) and BAP1 (0.3%). MC1R common variants (≥2 variants and ≥2 RHC variants) were associated with melanoma risk (OR 1.4; 95% CI 1.0-2.0 and OR 4.3; 95% CI 1.2-14.6, respectively). CONCLUSIONS: Variants in known high-penetrance genes explain nearly 20% of melanoma familial aggregation in Mediterranean areas. CDKN2A melanoma predictors were identified with potential clinical relevance for cancer risk assessment.

Synchronous primary cutaneous melanomas: a descriptive study of their clinical features, histology, genetic background of the patients and clinical outcomes.

BACKGROUND: Around 0.5% of cutaneous melanoma (CM) patients will present with synchronous melanomas when first seen. Moreover, 26-40% of patients with multiple primary melanomas present with synchronous lesions. OBJECTIVES: To assess the prevalence, clinical and histopathological characteristics, germline mutations and outcome in patients with synchronous melanoma. METHODS: Clinical and histopathological data from 4703 melanoma patients were included. Clinical, histological and genetic mutational status information was analysed. Kaplan-Meier curves were used to investigate survival outcomes. RESULTS: A total of 144 patients (3.06%) presented simultaneously with two or more primary melanomas. During follow-up, 25.7% of patients with synchronous melanoma developed a new primary melanoma compared to 8.6% of patients diagnosed with single melanoma (P < 0.001). Germinal CDKN2A mutations were identified in 10.7% of patients with synchronous melanomas and genetic variants in MC1R in 72%. No significant differences in all survival outcomes between patients with synchronous melanomas and single melanomas were found. CONCLUSION: Synchronous melanomas are more frequent than previously reported and are more frequent in older patients compared to single melanomas. Moreover, these patients have a higher risk of developing a new primary melanoma during follow-up and have higher rates of germline susceptibility variants. Nevertheless, these findings were not associated with worse outcomes.

Dermoscopy comparative approach for early diagnosis in familial melanoma: influence of MC1R genotype.

BACKGROUND: MC1R polymorphisms interact with CDKN2A mutations modulating melanoma risk and contribute to a less suspicious clinical and dermoscopic appearance of melanomas. Different strategies, including dermoscopic comparative approach and digital monitoring, are used for the melanoma diagnosis in this context. OBJECTIVE: To analyse the diagnostic accuracy of the morphologic approach and comparative approach in dermoscopy, and to detect melanoma in familial melanoma (FamMM) patients according to different genetic backgrounds. METHODS: Two independent readers evaluated 415 lesions belonging to 25 FamMM: 26 melanomas (62% in situ, 36% early invasive) and 389 naevi, blinded for dermoscopic and histopathologic diagnosis, following two different steps. First step-Randomized: all lesions were randomly located in one single folder. Second step-Comparative approach: the lesions were clustered by patient. Sensitivity, specificity and number needed to excise (NNE) for melanoma diagnosis were calculated for both diagnostic strategies. Sensitivity and specificity were also assessed regarding the genetic background. RESULTS: The comparative approach showed lower sensitivity compared to the morphologic approach (69.2 and 73.1 vs. 76.9 both readers) but better specificity (95.9 and 95.1 vs. 84.3 and 90.2, respectively). NNE was better in the comparative approach. The readers had more difficulties diagnosing lesions from CDKN2A mutation carriers with red hair colour (RHC) MC1R variants. CONCLUSION: The comparative approach can be useful in high-risk patients to decrease the NNE. Early melanomas in CDKN2A carriers with RHC polymorphisms are more difficult to diagnose even with the comparative approach and benefit from the detection of changes during digital dermoscopy monitoring for early diagnosis.

Should cell-free DNA testing be used in pregnancy with increased fetal nuchal translucency?

OBJECTIVE: To assess the frequency of atypical chromosomal and submicroscopic anomalies, as well as fetal structural abnormalities, observed on first-trimester ultrasound scan in fetuses with nuchal translucency (NT) thickness > 99th centile, in order to evaluate the suitability of using standard cell-free DNA (cfDNA) testing as the sole screening test in these pregnancies. METHODS: This was a retrospective cohort study of 226 fetuses with NT > 99th centile at 11-14 weeks' gestation, between January 2013 and December 2017, in a clinical setting in which greater than 95% of pregnant women receive first-trimester combined screening. All patients underwent genetic testing by means of quantitative fluorescence polymerase chain reaction and chromosomal microarray analysis, mainly in chorionic villus samples. We assessed the theoretical yield of two cfDNA testing models, targeted cfDNA (chromosomes 21, 18 and 13) and extended cfDNA (chromosomes 21, 18, 13 and sex chromosomes), and compared it with that of cytogenetic testing and ultrasound assessment in the first and second or third trimesters. RESULTS: In the 226 fetuses analyzed, cytogenetic testing revealed 84 (37%) anomalies, including 68 typical aneuploidies (involving chromosomes 13, 18 or 21), six sex chromosome aneuploidies (four cases of monosomy X and two of trisomy X), three clinically relevant atypical chromosomal anomalies (one trisomy 22, one trisomy 21 mosaicism and one unbalanced translocation), five submicroscopic pathogenic variants and two cases with Noonan syndrome. Targeted and extended cfDNA testing would miss at least 12% (10/84) and 19% (16/84), respectively, of genetic anomalies, accounting for 4.4% and 7.1% of the fetuses with an increased NT, respectively. Finally, of the 142 fetuses with no identified genetic anomaly, a major fetal malformation was observed in 15 (10.6%) fetuses at the early anomaly scan, and in 19 (13.4%) in the second or third trimester. CONCLUSIONS: cfDNA does not appear to be the appropriate genetic test in fetuses with NT > 99th centile, given that it would miss 12-19% of genetic anomalies in this group. Additionally, first-trimester ultrasound will identify a major structural abnormality in 11% of the fetuses with NT > 99th centile and no genetic anomaly. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

POT1 germline mutations but not TERT promoter mutations are implicated in melanoma susceptibility in a large cohort of Spanish melanoma families.

BACKGROUND: Germline mutations in telomere-related genes such as POT1 and TERT predispose individuals to familial melanoma. OBJECTIVES: To evaluate the prevalence of germline mutations in POT1 and TERT in a large cohort of Spanish melanoma-prone families (at least two affected first- or second-degree relatives). METHODS: Overall, 228 CDKN2A wild-type melanoma-prone families were included in the study. Screening of POT1 was performed in one affected person from each family and TERT was sequenced in one affected patient from 202 families (26 families were excluded owing to DNA exhaustion/degradation). TERT promoter sequencing was extended to an additional 30 families with CDKN2A mutation and 70 patients with sporadic multiple primary melanoma (MPM) with a family history of other cancers. RESULTS: We identified four families with potentially pathogenic POT1 germline mutations: a missense variant c.233T>C (p.Ile78Thr); a nonsense variant c.1030G>T (p.Glu344*); and two other variants, c.255G>A (r.125_255del) and c.1792G>A (r.1791_1792insAGTA, p.Asp598Serfs*22), which we confirmed disrupted POT1 mRNA splicing. A TERT promoter variant of unknown significance (c.-125C>A) was detected in a patient with MPM, but no germline mutations were detected in TERT promoter in cases of familial melanoma. CONCLUSIONS: Overall, 1·7% of our CDKN2A/CDK4-wild type Spanish melanoma-prone families carry probably damaging mutations in POT1. The frequency of TERT promoter germline mutations in families with melanoma in our population is extremely rare.

Novel clinical and molecular findings in Spanish patients with naevoid basal cell carcinoma syndrome.

BACKGROUND: Naevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterized by developmental alterations and multiple basal cell carcinomas. Mutations in PTCH1, which encodes a membrane receptor for Sonic Hedgehog, are associated with the development of the disease. Most of them produce a truncated protein, which is unable to suppress Smoothened protein and continuously activates the downstream pathway. OBJECTIVES: We aimed to characterize 22 unrelated Spanish patients with NBCCS, the largest cohort with Gorlin syndrome reported to date in Spain. METHODS: Genomic analysis of PTCH1 was performed in patients with NBCCS and controls, and mutations were analysed using bioinformatics tools. RESULTS: We report for the first time two young patients, one each with uterus didelphys and ganglioneuroma, within the context of NBCCS. One patient showing a severe phenotype of the disease had developed basal cell carcinomas since childhood. Sanger sequencing of PTCH1 in this cohort identified 17 novel truncating mutations (11 frameshift, five nonsense and one mutation affecting an exon-intron splice site) and two novel missense mutations that were predicted to be pathogenic. The patients showed great clinical variability and inconsistent genotype-phenotype correlation, as seen in relatives carrying similar mutations. CONCLUSIONS: This study contributes to increase the pool of clinical manifestations of NBCCS, as well as increasing the number of pathogenic mutations identified in PTCH1 predisposing to the condition. The inconsistencies found between phenotype and genotype suggest the involvement of other modifying factors, genetic, epigenetic or environmental.

Acquired erythropoietic uroporphyria secondary to myelodysplastic syndrome with chromosome 3 alterations: a case report.

Congenital erythropoietic porphyria is a rare autosomal recessive disease caused by a deficiency of uroporphyrinogen III synthase, owing to mutations in UROS in chromosome 10. Occasionally, patients show a mild, late-onset disease, without germline UROS mutations, associated with haematological malignancies. We report a 65-year-old patient with photosensitivity, overexcretion of porphyrins and thrombocytopenia. Bone marrow analysis gave a diagnosis of myelodysplastic syndrome (MDS) with the presence of a derivative chromosome 3, possibly due to an inversion including 3q21 and 3q26 break points. After allogeneic stem-cell transplantation, complete remission of MDS and uroporphyria was achieved. To our knowledge, this is the first reported case of acquired erythropoietic uroporphyria associated with MDS, with chromosome 3 alterations.

Association between dermoscopic and reflectance confocal microscopy features of cutaneous melanoma with BRAF mutational status.

BACKGROUND: Melanomas harbouring common genetic mutations might share certain morphological features detectable with dermoscopy and reflectance confocal microscopy. BRAF mutational status is crucial for the management of metastatic melanoma. OBJECTIVES: To correlate the dermoscopic characteristics of primary cutaneous melanomas with BRAF mutational status. Furthermore, a subset of tumours has also been analysed for the presence of possible confocal features that might be linked with BRAF status. METHODS: Retrospectively acquired dermoscopic and confocal images of patients with melanoma in tertiary referral academic centres: Skin Cancer Unit in Reggio Emilia and at the Melanoma Unit in Barcelona. Kruskal-Wallis test, logistic regressions, univariate and multivariate analyses have been performed to find dermoscopic and confocal features significantly correlated with BRAF mutational status. RESULTS: Dermoscopically, the presence of irregular peripheral streaks and ulceration were positive predictors of BRAF-mutated melanomas with a statistically significance value, while dotted vessels were more represented in wild-type melanomas. None of the evaluated reflectance confocal microscopy features were correlated with genetic profiling. CONCLUSIONS: Ulceration and irregular peripheral streaks represent dermoscopic feature indicative for BRAF-mutated melanoma, while dotted vessels are suggestive for wild-type melanoma.

Genetic susceptibility to cutaneous melanoma in southern Switzerland: role of CDKN2A, MC1R and MITF.

BACKGROUND: Nearly 10% of all cases of cutaneous melanoma (CM) occur in patients with a personal or family history of the disease. OBJECTIVES: To obtain information about genetic predisposition to CM in Ticino, the southern region of Switzerland, a zone with moderate-to-high CM incidence. METHODS: We identified germline mutations in highly CM-associated genes (CDKN2A and CDK4) and low/medium-penetrance variants (MC1R and MITF) in patients with multiple primary CMs or individuals with one or more CM and a positive family history for CM or pancreatic cancer among first- or second-degree relatives. Healthy blood donors (n = 146) were included as a control group. RESULTS: From July 2010 to July 2012, 57 patients (41 pedigrees) were included. Twenty-six were melanoma-prone families (with at least two cases) and 15 had multiple CMs. Pancreatic cancer was found in six families. The CDKN2A mutation p.V126D was identified in seven patients (four families) with a founder effect, whereas CDKN2A A148T was detected in seven cases (five families) and seven healthy donors (odds ratio 2·76, 95% confidence interval 0·83-9·20). At least one MC1R melanoma-associated polymorphism was detected in 32 patients (78%) and 97 healthy donors (66%), with more than one polymorphism in 12 patients (29%) and 25 healthy donors (17%). The MITF variant p.E318K was identified in four patients from three additional pedigrees (7%) and one healthy control (0·7%). CONCLUSIONS: Inclusion criteria for the Ticino population for genetic assessment should follow the rule of two (two affected individuals in a family or a patient with multiple CMs), as we detected a CDKN2A mutation in almost 10% of our pedigrees (four of 41), MITF p.E318K in 7% (three of 41) and a higher number of MC1R variants than in the control population.

Late-onset cutaneous porphyria in a patient heterozygous for a uroporphyrinogen III synthase gene mutation.

Deficiency of uroporphyrinogen III synthase (UROS) causes congenital erythropoietic porphyria (CEP). The disease, originating from the inheritance of mutations within the UROS gene, presents a recessive form of transmission. In a few patients, a late-onset CEP-like phenotype without UROS mutations appears to be associated with a myelodysplastic syndrome. We report a 60-year-old man with late-onset signs of cutaneous porphyria and accumulation in urine, plasma and faeces of type I porphyrin isomers characteristic of CEP. Analysis of DNA from peripheral leucocytes, skin and bone marrow aspirate showed that he was a heterozygous carrier of a Cys73Arg (c.217 T>C) mutation within UROS. Sequencing of cDNA from peripheral blood confirmed heterozygosity and expression of the normal allele. Measurement of UROS enzymatic activity in erythrocytes showed values ~70% of normal, indirectly indicating expression of the normal allele. Differently from other cases of late-onset uroporphyria, the patient did not present thrombocytopenia or any evidence of a myelodysplastic syndrome. Five years of clinical follow-up showed persistence of skin signs and increased excretion of porphyrins, independently of lifestyle factors or changes in medication regimes. We hypothesize acquired mosaicism (in the bone marrow) affecting the UROS gene. Thus, unstable cellular clones initiated overproduction of isomer I porphyrins leading to a CEP phenotype. This could be explained either by a clonal expansion of the porphyric (Cys73Arg) allele or by loss of function of the normal allele. Cellular turnover would facilitate release of uroporphyrins into circulation and subsequent skin lesions. This is the first case of a CEP heterozygous carrier presenting clinical manifestations.

Mutational status of naevus-associated melanomas.

BACKGROUND: The origin of melanoma has always been a debated subject, as well as the role of adjacent melanocytic naevi. Epidemiological and histopathological studies point to melanomas arising either de novo or from a naevus. OBJECTIVES: To evaluate the presence of mutations in genes from well-known melanomagenesis pathways in a large series of naevus-associated melanomas. MATERIALS AND METHODS: Sixty-one melanomas found in association with a pre-existing naevus were microdissected, after careful selection of cell subpopulations, and submitted to Sanger sequencing of the BRAF, NRAS, c-KIT, PPP6C, STK19 and RAC1 genes. Each gene was evaluated twice in all samples by sequencing or by sequencing and another confirmation method, allele-specific fluorescent polymerase chain reaction (PCR) and capillary electrophoresis detection or by SNaPshot analysis. Only mutations confirmed via two different molecular methods or twice by sequencing were considered positive. RESULTS: The majority of cases presented concordance of mutational status between melanoma and the associated naevus for all six genes (40 of 60; 66.7%). Nine cases presented concomitant BRAF and NRAS mutations, including one case in which both the melanoma and the adjacent naevus harboured V600E and Q61K double mutations. In two cases, both melanoma and associated naevus located on acral sites were BRAF mutated, including an acral lentiginous melanoma. CONCLUSIONS: To our knowledge this is the largest naevus-associated melanoma series evaluated molecularly. The majority of melanomas and adjacent naevi in our sample share the same mutational profile, corroborating the theory that the adjacent naevus and melanoma are clonally related and that the melanoma originated within a naevus.

Dermoscopic criteria associated with BRAF and NRAS mutation status in primary cutaneous melanoma.

BACKGROUND: The identification of BRAF mutations in melanoma led to the development and implementation of new and effective therapies. Few clinical and histological features have been associated with this mutational status. OBJECTIVES: The main objective of this study was to investigate clinical, histopathological and dermoscopic characteristics of primary melanomas according to BRAF or NRAS mutational status. METHODS: An observational retrospective study including melanoma dermoscopy images assessed for somatic mutations in BRAF and NRAS. RESULTS: Seventy-two patients were included, 30 women (42%) and 42 men (58%), mean age was 59 ± 15.51 years. BRAF-mutated melanomas were more frequently located on the trunk (n = 18, 64% for BRAF-mutated vs. n = 11, 29% for wild-type melanomas, P = 0.013). Histological ulceration was associated with the presence of BRAF mutations [odds ratio (OR) 3.141; 95% confidence interval (CI) 1.289-7.655; P = 0.002]. The Breslow index tended to be thicker in BRAF-mutated compared with wild-type (P = 0.086). BRAF mutations were present in 28 (39%) patients and only four cases were positive for NRAS mutations (6%), BRAF and NRAS mutations being mutually exclusive. The presence of dermoscopic peppering was associated with MAPK mutations (BRAF and NRAS) (OR 1.68; 95% CI 1.089-2.581; P = 0.015). Dermoscopic ulceration was also associated with BRAF mutations excluding acral and facial melanomas (OR 2.64; 95% CI 1.032-6.754). CONCLUSIONS: This study showed a correlation between BRAF and NRAS status and dermoscopic findings of 'peppering' as an expression of regression and melanophages in the dermis, suggesting a morphological consequence of immune behaviour in BRAF-mutated melanomas.

Distribution of MC1R variants among melanoma subtypes: p.R163Q is associated with lentigo maligna melanoma in a Mediterranean population.

BACKGROUND: Cutaneous melanoma tumour is classified into clinicohistopathological subtypes that may be associated with different genetic and host factors. Variation in the MC1R gene is one of the main factors of risk variation in sporadic melanoma. The relationship between MC1R variants and the risk of developing a specific subtype of melanoma has not been previously explored. OBJECTIVES: To analyse whether certain MC1R variants are associated with particular melanoma subtypes with specific clinicohistopathological features. METHODS: An association study was performed between MC1R gene variants and clinicopathological subtypes of primary melanoma derived from 1679 patients. RESULTS: We detected 53 MC1R variants (11 synonymous and 42 nonsynonymous). Recurrent nonsynonymous variants were p.V60L (30·0%), p.V92M (11·7%), p.D294H (9·4%), p.R151C (8·8%), p.R160W (6·2%), p.R163Q (4·2%) p.R142H (3·3%), p.I155T (3·8%), p.V122M (1·5%) and p.D84E (1·0%). Melanoma subtypes showed differences in the total number of MC1R variants (P = 0·028) and the number of red hair colour variants (P = 0·035). Furthermore, an association between p.R163Q and lentigo maligna melanoma was detected under a dominant model of heritance (odds ratio 2·16, 95% confidence interval 1·07-4·37; P = 0·044). No association was found between p.R163Q and Fitzpatrick skin phototype, eye colour or skin colour, indicating that the association was independent of the role of MC1R in pigmentation. No association was observed between MC1R polymorphisms and other melanoma subtypes. CONCLUSIONS: Our findings suggest that certain MC1R variants could increase melanoma risk due to their impact on pathways other than pigmentation, and may therefore be linked to specific melanoma subtypes.

Multiple primary melanomas: do they look the same?

BACKGROUND: A series of studies has investigated epidemiological, clinical and genetic characteristics of patients with multiple primary melanoma (MPM). However, comparison of the clinical and dermoscopic features of MPM within a given individual has been described only in case reports. OBJECTIVES: To describe the dermoscopic features of MPM for each given patient, and to evaluate the characteristics eventually associated with similar or dissimilar appearance. METHODS: From the databases of three skin-lesion clinics in the U.S.A., Italy and Spain we collected the dermoscopic images of melanomas in patients diagnosed with MPM. RESULTS: Among 58 patients with MPM, we found that 53% of patients had dermoscopically similar melanomas and 47% of patients had dermoscopically different melanomas. In older patients 59% of melanomas were dermoscopically similar vs. 47% in younger patients (P=0·377). Similar thickness was associated with the occurrence of dermoscopically similar melanomas (19/30 cases, 63%; P=0·039). Most (65%) of the synchronous lesions were similar, compared with 36% of nonsynchronous lesions (P=0·029), and most (69%) of the melanomas on sun-damaged skin were similar, vs. 37% of melanomas on nonsun-damaged skin (P=0·015; odds ratio 3·88, 95% confidence interval 1·11-13·98). The percentage of dermoscopically different melanomas was higher in patients with a family history of melanoma (67% vs. 48%). CONCLUSIONS: MPMs in a given patient have almost the same chance of looking dermoscopically similar or different. However, a subset of elderly patients with sun-damaged skin may present multiple, similar, thin melanomas characterized by pigment-network and regression structures.

Benefits of oral Polypodium Leucotomos extract in MM high-risk patients.

BACKGROUND: UV radiation and the presence of melanocytic nevi are the main risk factors of sporadic melanoma (MM). Protection of skin by an oral photoprotective agent would have substantial benefits. OBJECTIVE: We investigated the possible role of an oral Polypodium leucotomos (PL) extract to improve systemic photoprotection in patients at risk of skin cancer analyzing the ability to decrease UV-induced erythema. We also studied the interaction among MC1R polymorphisms and CDKN2A status with the minimal erythematous dose (MED) and their influence in the response after oral PL. METHODS: A total of 61 patients (25 with familial and/or multiple MM, 20 with sporadic MM and 16 with atypical mole syndrome without history of MM) were exposed to varying doses of artificial UVB radiation without and after oral administration of a total dose of 1080 mg of PL. RESULTS: Oral PL treatment significantly increased the MED mean in all group patients (0.123 to 0.161 J/cm(2) , p<0.05). Although not significant, we noticed a stronger effect of PL on the MED of patients with familial MM compared to those with MM (U=273, p=0.06). Among the patients with familial MM, those exhibiting a mutated CDKN2A and/or polymorphisms in MC1R had the bigger differences in response to treatment with PL. LIMITATIONS: Reduced number of patients. No control population. CONCLUSIONS: Administration of PL leads to a significant reduction of sensitivity to UVR (p<0.05) in all patients. Dark-eye patients and patients with higher UVR sensibility (lower basal MED) would be the most benefited from oral PL treatment.

Hepatoerythropoietic porphyria due to a novel mutation in the uroporphyrinogen decarboxylase gene.

BACKGROUND: Hepatoerythropoietic porphyria (HEP) is a rare form of porphyria that results from a deficiency of uroporphyrinogen decarboxylase (UROD). The disease is caused by homoallelism or heteroallelism for mutations in the UROD gene. OBJECTIVE: To study a 19-year-old woman from Equatorial Guinea, one of the few cases of HEP of African descent and to characterize a new mutation causing HEP. METHODS: Excretion of porphyrins and residual UROD activity in erythrocytes were measured and compared with those of other patients with HEP. The UROD gene of the proband was sequenced and a new mutation identified. The recombinant UROD protein was purified and assayed for enzymatic activity. The change of amino acid mapped to the UROD protein and the functional consequences were predicted. RESULTS: The patient presented a novel homozygous G170D missense mutation. Porphyrin excretion showed an atypical pattern in stool with a high pentaporphyrin III to isocoproporphyrin ratio. Erythrocyte UROD activity was 42% of normal and higher than the activity found in patients with HEP with a G281E mutation. The recombinant UROD protein showed a relative activity of 17% and 60% of wild-type to uroporphyrinogen I and III respectively. Molecular modelling showed that glycine 170 is located on the dimer interface of UROD, in a loop containing residues 167-172 that are critical for optimal enzymatic activity and that the carboxyl side chain from aspartic acid is predicted to cause negative interactions between the protein and the substrate. CONCLUSIONS: The results emphasize the complex relationship between the genetic defects and the biochemical phenotype in homozygous porphyria.

Fragile X syndrome prenatal diagnosis: parental attitudes and reproductive responses.

Fragile X syndrome (FXS) is the most common inherited form of mental retardation. It is caused by a CGG repeat expansion, which results in hypermethylation and silencing of the FMR1 gene. The results from 213 FXS prenatal diagnoses performed in the study centre were reviewed. Family history of FXS or undiagnosed mental retardation (MR) were the reasons for referral and 64% of mothers were not aware of their status so prenatal and mother tests were performed at the same time. Among those women referred for family history of unknown MR, 17.6% were found to be FXS carriers. The attitudes and perceptions of the syndrome of 52 FXS carriers were also evaluated. Most of them had been diagnosed as carriers when the child was already born and the most common feeling was sadness, followed by impotence and guilt. The majority of them had received genetic counselling and they considered it useful. Regarding reproductive options, prenatal diagnosis was chosen by 40.5% of women. Prenatal diagnosis for FXS is a good reproductive option and it should be carried out whenever family history of MR is present. A high percentage of FXS carriers are detected following this approach.