Screening and instability of FMR1 alleles in a prospective sample of 24,449 mother-newborn pairs from the general population.

To study the instability of FMR1 triplet repeats in the general population, we screened a prospective sample of 24,449 anonymized mother-offspring pairs and analyzed transmissions of intermediate-size (45-54 triplets) and premutation-size (55-200 triplets) alleles. We screened all mothers for alleles > or = 45 triplets by Southern blot and studied transmission of 545 maternal alleles to their offspring using polymerase chain reaction. Out of 21,411 maternal samples with conclusive results, we identified 250 carriers of at least one intermediate-size allele and 39 carrying a premutation-size allele. Out of a subsample of 430 transmissions of normal-size alleles (< 45 triplets), we observed four (< 1%) unstable transmissions. There were 6/90 intermediate-size unstable alleles (7%) and 11/25 unstable premutation-size alleles (44%). Two mothers transmitted a typical full mutation. The incidence of fragile X syndrome was thus 1/12,225 newborns (upper limit of 95% confidence interval: 1/4638 newborns), but larger in males (1/6209) than females (none detected in over 12,000 newborn females). Intermediate-size alleles were more unstable than normal-size alleles (p = 0.0027), but more stable (about sixfold) than premutation-size alleles (p < 0.0001). Unstable premutation-size alleles harbored the major fragile X haplotype (T50-T42-T62), and this haplotype appeared to be a good predictor of instability in premutations (p = 0.02). Incidence and instability are important to determine the feasibility and cost effectiveness of putative FMR1 screening programs. Carriers of FMR1 alleles of 55+ triplets with no family history of the disease may have a significant risk of expansion to a full mutation in a single generation.

Affinity-selected heparan sulfate for bone repair.

Bone morphogenetic protein (BMP)-2 is a potent bone healing compound produced at sites of bone trauma. Here we present a therapeutic strategy to harness the activity of endogenously produced BMP-2 by delivery of an affinity-matched heparan sulfate (HS) glycos aminoglycan biomaterial that increases the bioavailability, bioactivity and half-life of this growth factor. We have developed a robust, cost effective, peptide-based affinity platform to isolate a unique BMP-2 binding HS variant from commercially available preparations of HS, so removing the manufacturing bottleneck for their translation into the clinic. This affinity-matched HS enhanced BMP-2-induced osteogenesis through improved BMP-2 kinetics and receptor modulation, prolonged pSMAD signaling and reduced interactions with its antagonist noggin. When co-delivered with a collagen implant, the HS was as potent as exogenous BMP-2 for the healing of critical-sized bone defects in rabbits. This affinity platform can be readily tuned to isolate HS variants targeted ata range of clinically-relevant growth and adhesive factors.

Premutation and intermediate-size FMR1 alleles in 10572 males from the general population: loss of an AGG interruption is a late event in the generation of fragile X syndrome alleles.

We previously reported a 1:259 prevalence of female carriers of FMR1 premutation-size alleles (greater than 54 triplet repeats) in the general population. We now have screened 10 572 independent males from the same population for similar alleles using high-throughput Southern blotting. We identified 13 male carriers of an allele with more than 54 repeats. This corresponds to a prevalence of 1:813 males (95% confidence interval 1:527 to 1:1781). Haplotype analysis of four markers flanking the triplet array revealed that the prevalence of the major fragile X mutation-associated haplotype was increased among FMR1 alleles of 40-54 repeats. Although sequencing of highly unstable premutation alleles from fragile X families revealed only pure CGG tracts, this was not the case for alleles of similar size that were identified in males from the general population. Forty-eight out of forty-nine alleles of 40 or more triplets had one or two AGG interruptions. This observation, combined with the observation of the enrichment of major fragile X syndrome haplotypes in all alleles of this size, is evidence that the loss of an AGG interruption in the triplet repeat array is not necessary for expansion of normal alleles of 29-30 triplets to intermediate size. The loss of AGG interruptions thus appears to be a late event that leads to greatly increased instability and may be related to the haplotype background of specific FMR1 alleles.

Influence of family planning counseling in an adolescent clinic on sexual activity and contraceptive use.

We evaluated whether family planning counseling (FPC) in an adolescent clinic promoted the onset of sexual activity among the non-sexually active teens and/or increased contraceptive use among the sexually active teens. The FPC focused on the teens' establishing sexual values, the right to say "no," abstinence and alternate forms of intimacy, consequences of intercourse, and the various contraceptive methods. Data for one year were collected on the adolescents' first and subsequent visits to a medically oriented, municipal outpatient adolescent clinic. There were 383 teenagers who qualified for the study. Of these, 35% (134) reported premarital sexual activity. During the study period, 3% (8) of the 249 nonsexually active teens reported becoming sexually active. Among the 134 sexually active teens at clinic entry, 27% reported using a contraceptive method at their most recent sexual encounter. Among the 142 sexually active adolescents at the conclusion of the study, 76% reported contraceptive use at their most recent sexual encounter (p less than 0.001). We conclude that the provision of FPC to nonsexually active and sexually active teens does not appear to promote the onset of sexual activity significantly among the non-sexually active group, although it significantly increases contraceptive use among the sexually active group.

PIP: Whether family planning counselling (FPC) in an adolescent clinic promoted the onset of sexual activity among non-sexually active adolescents and/or increased contraceptive use among sexually active adolescents was evaluated. The FPC focused on the adolescents' establishing sexual values, the right to say "no," abstinence and alternate forms of intimacy, consequences of intercourse, and various contraceptive methods. Data for 1 year were collected on adolescents' 1st and subsequent visits to a medically-oriented, municipal outpatient adolescent clinic located in a predominately Hispanic, working-poor area of New York City. 383 adolescents qualified for the study. Of these, 35% (134) reported premarital sexual activity. during the study period, 3% (8) of the 249 non-sexually active adolescents reported becoming sexually active. Among the 134 adolescents sexually active at clinic entry, 27% reported using a contraceptive method at their most recent sexual encounter. Among the 142 sexually active adolescents at the conclusion of the study, 76% reported contraceptive use at their most recent sexual encounter (p 0.001). It was concluded that FPC provision to non-sexually active and sexually active teens does not appear to promote the onset of sexual activity significantly among the non-sexually active group, although it significantly increases contraceptive use among the sexually active group.