Peggy Modaff

Natural history of rhizomelic chondrodysplasia punctata

Rhizomelic chondrodysplasia punctata (RCP) is a rare autosomal recessive disorder with many associated medical complications. Prior to this study, natural history information about RCP was limited and based on experiences with small populations of affected individuals. We delineate the natural history of RCP through systematic analysis of 35 previously unreported individuals (as well as review of 62 literature cases with respect to survival and cause of death). Survival, growth, and developmental expectations and medical needs are summarized based upon experience with this population. Survival is greater among this population than previously reported, with 90% surviving up to 1 year and 50% surviving up to 6 years. Cause of death is most often respiratory problem. All infants with RCP have joint contractures, bilateral cataracts, and severe growth and psychomotor delays. Recommendations for health supervision of children with RCP and for parental counseling are presented.

Mild hypophosphatasia mimicking severe osteogenesis imperfecta in utero: Bent but not broken

We describe a fifth instance of hypophosphatasia presenting with prenatal findings suggestive of a very severe bone dysplasia but with a subsequently benign course. Spontaneous improvement of long-bone angulation began prenatally. The postnatal course has been encouraging. This sixth clinical form of hypophosphatasia, which we suggest should be called the benign prenatal form of hypophosphatasia, should be added to the differential diagnostic possibilities considered when angulation or bowing of long bones is discovered prenatally.

Newborn Screening for Cystic Fibrosis: Parents’ Preferences Regarding Counseling At the Time of Infants’ Sweat Test

Newborn screening (NBS) protocols for cystic fibrosis (CF) are the first regional population-based programs to incorporate DNA analysis into their procedures. Research about these programs can inform policy and practice regarding how best to counsel families with abnormal NBS results. The grounded theory method guided interviews with 33 families whose infants had abnormal CF NBS results. A dimensional analysis of these interviews provided a theoretical framework describing parents’ preferences regarding counseling during their infants sweat test appointment. This framework describes the contexts and characteristics of the two main dimensions of parents’ preferences: factual information and emotional support. Factual information included learning about the probability of a CF diagnosis, CF disease facts, sweat test procedure, and CF genetics. Social support consisted of offering parents a choice about the timing and amount of CF information, showing empathy for their distress, instilling hope, personalizing counseling, and providing hospitality. This framework also explains the consequences of counseling that matched versus mismatched parental preferences in these domains. Counseling that matched parents preferences reduced parents’ distress while mismatched counseling tended to increase parents’ worry about their infant.

Errors in the prenatal diagnosis of children with achondroplasia

To provide data about the frequency of prenatal misdiagnosis in achondroplasia (Ach), we retrospectively abstracted data from 37 consecutive referrals of infants with Ach where ultrasound was performed prenatally. Nine of 37 (24 per cent) had a positive family history of Ach; all nine were correctly diagnosed prenatally. Of the 28 with no family history of Ach, 16 (57 per cent) were recognized to have abnormalities on ultrasound but none was given a definite diagnosis of Ach. Five families received an appropriate diagnosis of ‘most likely’ Ach and four others were given a non‐specific (but appropriate) diagnosis of some dwarfing disorder, not otherwise specified. In seven instances (25 per cent), an incorrect diagnosis of a lethal or very severe disorder was provided. These results illustrate the difficulty of making a specific prenatal diagnosis of Ach. In the face of the resulting uncertainty, physicians appear to elect to emphasize the most severe of alternative diagnoses. Given the homogeneity of mutations within the fibroblast growth factor receptor 3 (FGFR3) gene in the vast majority of patients with Ach, FGFR3 mutational analysis can be offered in every instance where a short‐limb disorder is ultrasonographically detected in the latter stages of pregnancy. This would reduce the amount of incorrect and potentially harmful information provided to families.

Mutations in PCYT1A, Encoding a Key Regulator of Phosphatidylcholine Metabolism, Cause Spondylometaphyseal Dysplasia with Cone-Rod Dystrophy

The spondylometaphyseal dysplasias (SMDs) are a group of about a dozen rare disorders characterized by short stature, irregular, flat vertebrae, and metaphyseal abnormalities. Aside from spondylometaphyseal dysplasia Kozlowski type (MIM 184252) caused by mutations in TRPV4 (MIM 605427) and spondyloenchondrodysplasia (MIM 607944) resulting from mutations in ACP5 (MIM 171640), the genetic etiologies of SMDs are unknown. 1 Two of these unexplained SMDs have ophthalmologic manifestations: SMD with cone-rod dystrophy (SMD-CRD [MIM 608940]) and axial SMD with retinal degeneration (MIM 602271). Delineated clinically a decade ago, SMD-CRD is a presumed autosomal-recessive disorder with postnatal growth deficiency leading to profound short stature; rhizomelia with bowing of the lower extremities; platyspondyly with anterior vertebral protrusions; progressive metaphyseal irregularity and cupping with shortened tubular bones; and early-onset, progressive visual impairment associated with a pigmentary maculopathy and electroretinographic evidence of cone-rod dysfunction. 2‐5 In contrast to retinitis pigmentosa, the CRDs have early involvement of cone photoreceptors. 6

Array-based comparative genomic hybridization (aCGH) in the genetic evaluation of stillbirth†‡

This study examined the utility of array‐based comparative genomic hybridization (aCGH) in detecting genetic abnormalities associated with late pregnancy loss. Comparisons were made with classic cytogenetics to test whether aCGH represents a superior methodology for the clinical evaluation of stillbirth. Stillborn infants were selected for aCGH testing from the Wisconsin Stillbirth Service Program (WiSSP) database and tissue bank, based on abnormal clinical findings (presence of at least two abnormalities of two different organs or parts of the body). aCGH analysis was successfully completed in 15 cases which met the clinical criteria and for which sufficient amount of high quality DNA was recovered from archival material. The testing was performed using commercially available 1 Mb BAC arrays. Among 15 tested stillborns, aCGH detected two abnormalities (trisomy 21 and an unbalanced translocation between chromosomes 3 and 10), for an overall detection rate of 13% in stillborns with malformations who had normal or unobtainable cytogenetic results. This preliminary study supports the clinical value of aCGH testing in diagnostic evaluation of stillborns with congenital anomalies.

A Tailored Approach to Family-Centered Genetic Counseling for Cystic Fibrosis Newborn Screening: The Wisconsin Model

This article describes the development of a tailored family-centered approach to genetic counseling following abnormal newborn screening (NBS) for cystic fibrosis (CF). A genetic counseling consortium reviewed research literature, selected theoretical frameworks, and incorporated counseling psychology micro skills. This innovative intervention integrated theories and empirically validated techniques. Pilot testing and parent feedback confirmed satisfaction with and feasibility of the approach designed to (a) minimize parents’ distress, (b) facilitate parents’ understanding, (c) increase parents’ capacities to use genetic information, and (d) enhance parents’ experiences with genetic counseling. Counselors engage in a highly interactive process of evaluating parents’ needs and tailoring assessments and interventions that include a therapeutic environment, the family’s emotional needs, parents’ informational needs, and a follow-up plan. This promising new model is the first to establish a theory-driven, evidence-based standard for genetic counseling in the context of NBS for CF. Additional research will evaluate the model’s efficacy in clinical practice.

Pelger–huet anomaly and a mild skeletal phenotype secondary to mutations in LBR

The Lamin B receptor (LBR) gene has been described to encode a bifunctional protein. Mutations in the LBR gene can affect neutrophil segmentation and sterol reductase activity and have been associated with two different recognized clinical conditions, Pelger–Huet anomaly (PHA) and Greenberg skeletal dysplasia. PHA is a benign autosomal co‐dominant laminopathy resulting in bilobed neutrophil nuclei in heterozygotes, and unsegmented (ovoid) neutrophil nuclei in homozygotes. Some putative PHA homozygotes have been reported with minor skeletal malformations. Greenberg skeletal dysplasia is a severe autosomal recessive, perinatal lethal dwarfing disorder in which heterozygous carriers are usually without clinical manifestations. We here report a girl who has bilobed neutrophil nuclei and a mild skeletal dysplasia. Mutation analysis showed two novel mutations in the LBR gene: c.651_653 delinsTGATGAGAAA (p.Ile218Aspfs*19) and c.1757G > A (p.Arg586His). These mutations were found to be in trans, and, thus, she is a compound heterozygote. Sterol analysis found trace amounts of cholesta‐8,14‐dien‐3beta‐ol, which is normally undetected in healthy individuals. This and previously reported cases suggest that mutations in LBR can result in a continuum of phenotypic manifestations.

A phenotype intermediate between Desbuquois dysplasia and diastrophic dysplasia secondary to mutations in DTDST

We describe a child whose original clinical and radiologic manifestations led to a diagnosis of Desbuquois dysplasia. Subsequent development of features including cervical kyphosis and cystic ears caused us to reconsider the original diagnosis. The new complement of features in this patient fell in a range between Desbuquois dysplasia and diastrophic dysplasia. Molecular testing showed that she is a compound heterozygote for mutations in the diastrophic dysplasia sulfate transporter gene (DTDST). This finding confirms that there is locus heterogeneity in apparent Desbuquois dysplasia. It also expands the phenotypic spectrum of disorders caused by mutations in DTDST.

Airway malacia in children with achondroplasia.

This study was undertaken to assess the frequency of airway malacia in infants and young children with achondroplasia, a population well known to be at risk for a variety of respiratory problems. We also wished to evaluate what, if any, contribution airway malacia makes to the complex respiratory issues that may be present in those with achondroplasia. Retrospective chart review of all infants and young children with achondroplasia who were assessed through the Midwest Regional Bone Dysplasia Clinics from 1985 through 2012 (n = 236) was completed. Records of comprehensive clinical examinations, polysomnographic assessments, and airway visualization were reviewed and abstracted using a data collection form. Analyses were completed comparing the group with and those without evidence for airway malacia. Thirteen of 236 patients (5.5%) were found to have airway malacia. Most of those affected had lower airway involvement (9/13). The presence of airway malacia was correlated with an increased occurrence of obstructive sleep apnea as well as need for oxygen supplementation, airway surgeries and tracheostomy placement. Although estimates of the frequency of airway malacia in the general population are limited, its frequency in children with achondroplasia appears to be much higher than any published general population estimate. The presence of airway malacia appears to confound other breathing abnormalities in this population and results in the need for more invasive airway treatments.