Fibrodysplasia ossificans progressiva in Spain: epidemiological, clinical, and genetic aspects

We aimed to investigate the epidemiological determinants, clinical features, and genetic pattern of FOP in our country by evaluating the entire population of patients identified according to a combination of methods. To achieve this, 24 individuals were confirmed as FOP cases, 17 of whom were alive at the end of 2011 (point prevalence=0.36 × 10(-6)). The gender distribution (male/female ratio=13/11) and the concurrent range of ages (from 4 to 53 years; mean ± SD: 30.2 ± 13.8) are in agreement with similar reports. Twenty-one (87.5%) had characteristic congenital malformations of the big toe, and short thumbs were found in 65.2% of cases. In addition, other skeletal malformations such us fusion of the posterior elements of the cervical spine (89.0%), knee osteochondromas (71%), scoliosis (54.5%), and short and broad femoral neck (52.6%) were observed. All had developed mature ossicles of heterotopic bone in typical anatomic and temporal patterns, ranging in number from 1 to 17 (9.5 ± 3.9). Age at appearance of first ossifying lesion varied from 3 months to 15 years. Mean age at diagnosis was 7.3 ± 5.1 years and the average delay in reaching the correct diagnosis after the onset of heterotopic ossification was 2.7 years (range=0-12 years). Biopsy of the pre-osseous lesions was performed in 11 of 20 (55.0%), providing no useful information for the diagnosis of FOP. Seven of 18 (38.9%) reported some hearing loss, and 5 (27.8%) experienced diffuse thinning of the hair or were bald. No patient had relatives with a typical FOP clinical picture. Fourteen of the 16 cases which were genetically investigated displayed the single heterozygous mutation c.617G>A in exon 4 of the ACVR1 gene. One of the two patients who did not present with the canonical ACVR1 mutation showed a heterozygous mutation c.774G>C in exon 5 leading to the substitution of Arginine 258 with a serine. The other patient had a heterozygous c.774G>T substitution in exon 5 leading to the same amino acid change (p.Arg258Ser). These two patients had only nonspecific abnormalities of the great toe, lacked the typical anatomic and developmental pattern of heterotopic ossification, and shared a trend toward uncommon clinical features. These results provide new insight on the epidemiological and clinical traits of FOP, reinforcing the notion of its worldwide homogeneity. The molecular characterization of ACVR1 sequence variation will contribute to the understanding of the genetic profile of this devastating disease in different geographical areas.

Further evidence supporting a genetic background for Paget's disease of bone in Spain

The aim of this paper is to investigate heritable factors that might be related to the recognised genetic susceptibility for developing Paget's disease of bone (PD). This was a hospital-based, case-control study of a systematically selected group of PD patients and a group of controls drawn from the same health setting. In these populations we assessed surname pattern, parental consanguinity and constitutional physical traits. In a separate case-control analysis, genetically-based features and pathological traits of interest for genetic inference in 43 demonstrated familial cases were then compared to those in 24 sporadic cases. Results showed coincidence of three or four surnames (Odds Ratio [OR] = 5.6; 95% CI = 1.7-18.5), degree of parental consanguinity (OR = 4.1; 95% CI = 2.1-1.8), and green or blue eye colour (OR = 1.5; 95% CI = 1.1-2.1) were significantly associated with PD. Comparison of proven familial and sporadic PD cases showed that the former had a stronger association with Monckeberg-type vascular calcifications (32% vs. 4%; p = 0.02), percentage of skeleton affected (13.1 vs. 9.0), and green and blue eye colour (82% vs. 25%; p = 0.006), with Monckeberg-type vascular calcifications being the main variable of interest (OR = 30.9; 95% CI = 12.75-347.00) in the multivariate analysis. In conclusion, heritable factors are crucial in the pathogenesis of PD and, in line with other data sources, might account for the ethnic predisposition observed in different countries.