Cervical Spine Deformities in Children With Rhizomelic Chondrodysplasia Punctata

BACKGROUND

Cervical spine deformity in rhizomelic chondrodysplasia punctata (RCDP) has been described with different findings reported in the literature. However, available literature provides limited data from a few cases with magnetic resonance imaging (MRI) of the cervical spine. Our report describes the MRI findings in a group of children with RCDP, aiming to reach a better understanding of this pathology.

METHODS

An Institutional Review Board-approved RCDP Registry was created at our institution with the goal of identifying pertinent medical issues over the lifespan of individuals with RCDP. Records of children within the registry were evaluated, and magnetic resonance images obtained between 2004 and 2015, were available for review. The levels of spinal canal stenosis were recorded and the severity of the stenosis was decided based on adults' parameters. Cord compression and myelomalacia were confirmed on the axial images. Sagittal lumbar spine magnetic resonance images were also evaluated when available, and the presence of tethered cord and fatty filum was recorded.

RESULTS

Twenty-six children (15 boys and 11 girls) were identified in the RCDP Registry. Eleven children (6 boys and 5 girls) had sagittal MRI of the cervical spine available for review. Age at the time of MRI study was variable (1 wk to 32 mo). All patients except 1 had stenosis of the cervical spinal canal. Myelomalacia of the cord was noted only in this patient.

CONCLUSIONS

This study suggests that, in children with RCDP, cervical spinal stenosis and cord compression are a real risk, and children with this diagnosis should have monitoring for these issues. Tethered cord is also a possible finding that needs to be evaluated. Full sagittal spine MRI is necessary to detect the possible deformities at the cervical and lumbar levels.

New insights into minor splicing-a transcriptomic analysis of cells derived from TALS patients

Minor intron splicing plays a central role in human embryonic development and survival. Indeed, biallelic mutations in RNU4ATAC, transcribed into the minor spliceosomal U4atac snRNA, are responsible for three rare autosomal recessive multimalformation disorders named Taybi-Linder (TALS/MOPD1), Roifman (RFMN), and Lowry-Wood (LWS) syndromes, which associate numerous overlapping signs of varying severity. Although RNA-seq experiments have been conducted on a few RFMN patient cells, none have been performed in TALS, and more generally no in-depth transcriptomic analysis of the ∼700 human genes containing a minor (U12-type) intron had been published as yet. We thus sequenced RNA from cells derived from five skin, three amniotic fluid, and one blood biosamples obtained from seven unrelated TALS cases and from age- and sex-matched controls. This allowed us to describe for the first time the mRNA expression and splicing profile of genes containing U12-type introns, in the context of a functional minor spliceosome. Concerning RNU4ATAC-mutated patients, we show that as expected, they display distinct U12-type intron splicing profiles compared to controls, but that rather unexpectedly mRNA expression levels are mostly unchanged. Furthermore, although U12-type intron missplicing concerns most of the expressed U12 genes, the level of U12-type intron retention is surprisingly low in fibroblasts and amniocytes, and much more pronounced in blood cells. Interestingly, we found several occurrences of introns that can be spliced using either U2, U12, or a combination of both types of splice site consensus sequences, with a shift towards splicing using preferentially U2 sites in TALS patients' cells compared to controls.

Biallelic variants in DNA2 cause microcephalic primordial dwarfism

Microcephalic primordial dwarfism (MPD) is a group of rare single-gene disorders characterized by the extreme reduction in brain and body size from early development onwards. Proteins encoded by MPD-associated genes play important roles in fundamental cellular processes, notably genome replication and repair. Here we report the identification of four MPD individuals with biallelic variants in DNA2, which encodes an adenosine triphosphate (ATP)-dependent helicase/nuclease involved in DNA replication and repair. We demonstrate that the two intronic variants (c.1764-38_1764-37ins(53) and c.74+4A>C) found in these individuals substantially impair DNA2 transcript splicing. Additionally, we identify a missense variant (c.1963A>G), affecting a residue of the ATP-dependent helicase domain that is highly conserved between humans and yeast, with the resulting substitution (p.Thr655Ala) predicted to directly impact ATP/ADP (adenosine diphosphate) binding by DNA2. Our findings support the pathogenicity of these variants as biallelic hypomorphic mutations, establishing DNA2 as an MPD disease gene.

Mobility in osteogenesis imperfecta: a multicenter North American study

PURPOSE

Osteogenesis imperfecta (OI) is a genetic connective tissue disorder that causes bone fragility. Phenotypic severity influences ability to walk, however, little is known about ambulatory characteristics of individuals with OI, especially in more severe forms. The purpose of this work was to characterize mobility in OI using standard clinical assessment tools and determine if patient characteristics could be used to predict mobility outcomes.

METHODS

We collected mobility data at five clinical sites to analyze the largest cohort of individuals with OI (n = 491) to date. Linear mixed models were developed to explore relationships among subject demographics and mobility metrics.

RESULTS

Results showed minor limitations in the mild group while the more severe types showed more significant limitations in all mobility metrics analyzed. Height and weight were shown to be the most significant predictors of mobility. Relationships with mobility and bisphosphonates varied with OI type and type used (oral/IV).

CONCLUSION

These results are significant to understanding mobility limitations of specific types of OI and beneficial when developing rehabilitation protocols for this population. It is important for physicians, patients, and caregivers to gain insight into severity and classification of the disease and the influence of disease-related characteristics on prognosis for mobility.

Best practice guidelines regarding diagnosis and management of patients with type II collagen disorders

PURPOSE

Skeletal dysplasias comprise a heterogeneous group of inherited disorders of development, growth, and maintenance of the human skeleton. Because of their relative rarity and wide phenotypic variability, patients should be accurately identified, uniformly assessed, and managed by clinicians who are aware of their potential complications and possess the knowledge and resources to treat them effectively. This study presents expert guidelines developed to improve the diagnosis and management of patients with type II collagen skeletal disorders to optimize clinical outcomes.

METHODS

A panel of 11 multidisciplinary international experts in the field of skeletal dysplasia participated in a Delphi process, which comprised analysis of a thorough literature review with subsequent generation of 26 diagnosis and care recommendations, followed by two rounds of anonymous voting with an intervening face-to-face meeting. Those recommendations with more than 80% agreement were considered as consensual.

RESULTS

After the first voting round, consensus was reached to support 12 of 26 (46%) statements. After the panel discussion, the group reached consensus on 22 of 24 revised statements (92%).

CONCLUSIONS

Consensus-based, expert best practice guidelines developed as a standard of care to assist accurate diagnosis, minimize associated health risks, and improve clinical outcomes for patients with type II collagen skeletal dysplasias.

A Multicenter Observational Cohort Study to Evaluate the Effects of Bisphosphonate Exposure on Bone Mineral Density and Other Health Outcomes in Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is characterized by low bone mass and bone fragility. Using data from a large cohort of individuals with OI from the Osteogenesis Imperfecta Foundation's linked clinical research centers, we examined the association between exposure to bisphosphonate (BPN) treatment (past or present) and lumbar spine (LS) areal bone mineral density (aBMD), fractures, scoliosis, and mobility. From 466 individuals, we obtained 1394 participant‐age LS aBMD data points. Though all OI subtypes were examined, primary analyses were restricted to type I OI (OI‐1). Using linear regression, we constructed expected OI‐1 LS aBMD‐for‐age curves from the data from individuals who had never received BPN. LS aBMD in those who had been exposed to BPN was then compared with the computed expected aBMD. BPN exposure in preadolescent years (age <14 years) was associated with a LS aBMD that was 9% more than the expected computed values in BPN‐naïve individuals (p < 0.01); however, such association was not observed across all ages. Exposure to i.v. BPN and treatment duration >2 years correlated with LS aBMD in preadolescent individuals. BPN exposure also had a significant association with non‐aBMD clinical outcome variables. Logistic regression modeling predicted that with BPN exposure, a 1‐year increase in age would be associated with an 8.2% decrease in fracture probability for preadolescent individuals with OI‐1, compared with no decrease in individuals who had never received any BPN (p < 0.05). In preadolescent individuals with OI‐1, a 0.1 g/cm² increase in LS aBMD was associated with a 10.6% decrease in scoliosis probability, compared with a 46.8% increase in the BPN‐naïve group (p < 0.01). For the same changes in age and LS aBMD in preadolescent individuals, BPN exposure was also associated with higher mobility scores (p < 0.01), demonstrating that BPN treatment may be associated with daily function. © 2018 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

GGC Repeat Expansion and Exon 1 Methylation of XYLT1 Is a Common Pathogenic Variant in Baratela-Scott Syndrome

Baratela-Scott syndrome (BSS) is a rare, autosomal-recessive disorder characterized by short stature, facial dysmorphisms, developmental delay, and skeletal dysplasia caused by pathogenic variants in XYLT1. We report clinical and molecular investigation of 10 families (12 individuals) with BSS. Standard sequencing methods identified biallelic pathogenic variants in XYLT1 in only two families. Of the remaining cohort, two probands had no variants and six probands had only a single variant, including four with a heterozygous 3.1 Mb 16p13 deletion encompassing XYLT1 and two with a heterozygous truncating variant. Bisulfite sequencing revealed aberrant hypermethylation in exon 1 of XYLT1, always in trans with the sequence variant or deletion when present; both alleles were methylated in those with no identified variant. Expression of the methylated XYLT1 allele was severely reduced in fibroblasts from two probands. Southern blot studies combined with repeat expansion analysis of genome sequence data showed that the hypermethylation is associated with expansion of a GGC repeat in the XYLT1 promoter region that is not present in the reference genome, confirming that BSS is a trinucleotide repeat expansion disorder. The hypermethylated allele accounts for 50% of disease alleles in our cohort and is not present in 130 control subjects. Our study highlights the importance of investigating non-sequence-based alterations, including epigenetic changes, to identify the missing heritability in genetic disorders.

DNA Polymerase Epsilon Deficiency Causes IMAGe Syndrome with Variable Immunodeficiency

During genome replication, polymerase epsilon (Pol ε) acts as the major leading-strand DNA polymerase. Here we report the identification of biallelic mutations in POLE, encoding the Pol ε catalytic subunit POLE1, in 15 individuals from 12 families. Phenotypically, these individuals had clinical features closely resembling IMAGe syndrome (intrauterine growth restriction [IUGR], metaphyseal dysplasia, adrenal hypoplasia congenita, and genitourinary anomalies in males), a disorder previously associated with gain-of-function mutations in CDKN1C. POLE1-deficient individuals also exhibited distinctive facial features and variable immune dysfunction with evidence of lymphocyte deficiency. All subjects shared the same intronic variant (c.1686+32C>G) as part of a common haplotype, in combination with different loss-of-function variants in trans. The intronic variant alters splicing, and together the biallelic mutations lead to cellular deficiency of Pol ε and delayed S-phase progression. In summary, we establish POLE as a second gene in which mutations cause IMAGe syndrome. These findings add to a growing list of disorders due to mutations in DNA replication genes that manifest growth restriction alongside adrenal dysfunction and/or immunodeficiency, consolidating these as replisome phenotypes and highlighting a need for future studies to understand the tissue-specific development roles of the encoded proteins.

A multicenter study to evaluate pulmonary function in osteogenesis imperfecta

Pulmonary complications are a significant cause for morbidity and mortality in osteogenesis imperfecta (OI). However, to date, there have been few studies that have systematically evaluated pulmonary function in individuals with OI. We analyzed spirometry measurements, including forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1 ), in a large cohort of individuals with OI (n = 217) enrolled in a multicenter, observational study. We show that individuals with the more severe form of the disease, OI type III, have significantly reduced FVC and FEV1 which do not follow the expected trends of the normal population. We also show that "normalization" of FVC and FEV1 using general population data to generate percent predicted values underestimates the pulmonary involvement in OI. Within each subtype of OI, we used linear mixed models to find potential correlations between FEV1 and FVC with the clinical variables including mobility, bisphosphonate use, and scoliosis. Our results are an important step in understanding the extent of pulmonary involvement in individuals with OI and for developing pulmonary endpoints for use in the routine patient care as well as in the investigation of new therapies.

Best practice guidelines regarding prenatal evaluation and delivery of patients with skeletal dysplasia

BACKGROUND

Skeletal dysplasia comprises a heterogeneous and collectively common group of inherited disorders of development, growth, and maintenance of the human skeleton. There is potential for increased perinatal morbidity and mortality in pregnant women who themselves have skeletal dysplasia, and for affected fetuses where skeletal dysplasia is suspected in utero.

OBJECTIVE

We sought to establish guidelines for perinatal health care professionals who should be aware of these risks, to optimize maternal and child health pregnancy outcomes through best prenatal and delivery management practices.

STUDY DESIGN

A panel of 13 multidisciplinary international experts participated in a Delphi process, which comprised consideration of thorough literature review and a list of 54 possible care recommendations subject to 2 rounds of anonymous voting and a face-to-face meeting. Those recommendations with >80% agreement were considered as consensual.

RESULTS

During the first round, consensus was reached to support 30 out of the 54 statements. After the panel discussion, the group reached consensus on 40 statements. These statements include guidelines for the evaluation and treatment of pregnant women with skeletal dysplasia and for the unborn child with or suspected to have skeletal dysplasia.

CONCLUSION

Consensus-based best practice guidelines are provided as a minimum of standard care to minimize associated health risks, and improve clinical outcomes for patients with skeletal dysplasia.

PCNT point mutations and familial intracranial aneurysms

OBJECTIVE

To identify novel genes involved in the etiology of intracranial aneurysms (IAs) or subarachnoid hemorrhages (SAHs) using whole-exome sequencing.

METHODS

We performed whole-exome sequencing in 13 individuals from 3 families with an autosomal dominant IA/SAH inheritance pattern to look for candidate genes for disease. In addition, we sequenced PCNT exon 38 in a further 161 idiopathic patients with IA/SAH to find additional carriers of potential pathogenic variants.

RESULTS

We identified 2 different variants in exon 38 from the PCNT gene shared between affected members from 2 different families with either IA or SAH (p.R2728C and p.V2811L). One hundred sixty-four samples with either SAH or IA were Sanger sequenced for the PCNT exon 38. Five additional missense mutations were identified. We also found a second p.V2811L carrier in a family with a history of neurovascular diseases.

CONCLUSION

The PCNT gene encodes a protein that is involved in the process of microtubule nucleation and organization in interphase and mitosis. Biallelic loss-of-function mutations in PCNT cause a form of primordial dwarfism (microcephalic osteodysplastic primordial dwarfism type II), and ≈50% of these patients will develop neurovascular abnormalities, including IAs and SAHs. In addition, a complete Pcnt knockout mouse model (Pcnt ^-/-) published previously showed general vascular abnormalities, including intracranial hemorrhage. The variants in our families lie in the highly conserved PCNT protein-protein interaction domain, making PCNT a highly plausible candidate gene in cerebrovascular disease.

A Recurrent De Novo Heterozygous COG4 Substitution Leads to Saul-Wilson Syndrome, Disrupted Vesicular Trafficking, and Altered Proteoglycan Glycosylation

The conserved oligomeric Golgi (COG) complex is involved in intracellular vesicular transport, and is composed of eight subunits distributed in two lobes, lobe A (COG1-4) and lobe B (COG5-8). We describe fourteen individuals with Saul-Wilson syndrome, a rare form of primordial dwarfism with characteristic facial and radiographic features. All affected subjects harbored heterozygous de novo variants in COG4, giving rise to the same recurrent amino acid substitution (p.Gly516Arg). Affected individuals' fibroblasts, whose COG4 mRNA and protein were not decreased, exhibited delayed anterograde vesicular trafficking from the ER to the Golgi and accelerated retrograde vesicular recycling from the Golgi to the ER. This altered steady-state equilibrium led to a decrease in Golgi volume, as well as morphologic abnormalities with collapse of the Golgi stacks. Despite these abnormalities of the Golgi apparatus, protein glycosylation in sera and fibroblasts from affected subjects was not notably altered, but decorin, a proteoglycan secreted into the extracellular matrix, showed altered Golgi-dependent glycosylation. In summary, we define a specific heterozygous COG4 substitution as the molecular basis of Saul-Wilson syndrome, a rare skeletal dysplasia distinct from biallelic COG4-CDG.

Multicenter study of mortality in achondroplasia

Sudden death and higher mortality are recognized in achondroplasia, with acute brainstem compression, a common cause of mortality in children <4 years and cardiovascular deaths being more prevalent in adults. Although, changes in clinical management have improved survival, mortality is still higher than in the general population. The aim of this multicenter clinic-based study was to assess the rate and causes of mortality in patients seen in clinic since 1986. Information was ascertained for achondroplasia patients clinically assessed in four skeletal dysplasia clinics. Data was sent to the National Death Index to identify vital status and cause of death. Standardized mortality rates (SMR) were calculated based on U.S. populations from 1975, 1995, and 2000. Eight hundred fifty-five patients were identified, contributing 12,117 person-years and a total of 12 deaths. One case died in infancy. In the 1-4 year age group, which had the highest age-adjusted SMR, three out of five deaths were because of cerebrovascular/cardiovascular events. Half the deaths in ages 5 through 24 were because of accidental events, including motor vehicle accidents. Decreased mortality in children with achondroplasia was noted, particularly in younger age groups. This improvement in childhood survival is outpaced by improved survival in the general population. Causes of death in these patients have shifted over the last 30 years, with fewer sudden death and deaths because of pneumonia or hydrocephalus countered by more cardiovascular or cerebrovascular and accidental deaths. Clinicians should be aware of the apparent increased risk of vehicular accidents and counsel patients accordingly.

Aneurysmal bone cysts and pathologic fracture associated with supernumerary ring chromosome 6 in two unrelated patients

Small supernumerary ring chromosome 6 (sSRC[6]) is a rare chromosomal abnormality characterized by a broad clinical phenotype. The spectrum of this disorder can range from phenotypically normal to severe developmental delay and congenital anomalies. We describe two unrelated patients with small SRCs derived from chromosome 6 with a novel bone phenotype. Both patients presented with a complex bone disorder characterized by severe osteopenia, pathologic fractures, and cyst-like lesions within the bone. Imaging revealed decreased bone mineral density, mutiple multiloculated cysts and cortical thinning. Lesion pathology in both patients demonstrated a bland cyst wall with woven dysplastic appearing bone entrapped within it. In patient 1, array comparative genomic hybridization (CGH) detected a tandem duplication of region 6p12.3 to 6q12 per marker chromosome. Cytogenetic analysis further revealed a complex patient of mosaicism with some cell lines displaying either one or two copies of the marker indicative of both tetrasomy and hexasomy of this region. Patient 2 was mosaic for a sSRC that encompassed a 26.8 Mb gain from 6p21.2 to 6q12. We performed an in-depth clinical analysis of a phenotype not previously observed in sSRC(6) patients and discuss the potential influence of genes located within this region on the skeletal presentation observed.

Metatropic dysplasia-a skeletal dysplasia with challenging airway and other anesthetic concerns

BACKGROUND

Metatropic dysplasia is a rare form of skeletal dysplasia requiring multiple anesthetics for surgical and imaging procedures, most of which are orthopedic procedures. We provide centralized care to patients with skeletal dysplasia at our tertiary care pediatric hospital, and we were able to collect the largest number of metatropic dysplasia patients reported to date.

AIM

The aim of this retrospective study was to describe and characterize the anesthetic difficulties in this high-risk population.

METHODS

Medical charts of all patients with metatropic dysplasia were reviewed to collect data, including anesthetics performed, difficulties, and complications related to the anesthetic care, co-morbid conditions, and related events.

RESULTS

Twenty-three patients with metatropic dysplasia underwent 188 anesthetics with 61% of the anesthetics having been administered for orthopedic procedures. Fourteen of 23 (60.8%) progressively became difficult to intubate over the course of their care, with 12 out of 14 having undergone cervical spine fusion. These 14 patients had a total of 133 procedures. Sixty procedures (45.1%) had an airway described as difficult. Glidescope was the difficult airway tool most commonly used (68%) with flexible fiberoptic scope used 12% and Miller or Macintosh blade used 18% of the time. In addition to the airway difficulties, spinal canal narrowing or stenosis was widely prevalent, and no neuraxial anesthetic was performed in any of our patients.

CONCLUSION

Difficult airway is the most common co-morbid condition present in patients with metatropic dysplasia, especially if their cervical spine has been fused. Familiarity with the difficulties involving the airway and its management is critical in safe and successful management of anesthesia in this high-risk population.

Microcephalic Osteodysplastic Primordial Dwarfism, Type II: a Clinical Review

PURPOSE OF THE REVIEW

This review will provide an overview of the microcephalic primordial dwarfism (MPD) class of disorders and provide the reader comprehensive clinical review with suggested care guidelines for patients with microcephalic osteodysplastic primordial dwarfism, type II (MOPDII).

RECENT FINDINGS

Over the last 15 years, significant strides have been made in the diagnosis, natural history, and management of MOPDII. MOPDII is the most common and well described form of MPD. The classic features of the MPD group are severe pre- and postnatal growth retardation, with marked microcephaly. In addition to these features, individuals with MOPDII have characteristic facies, skeletal dysplasia, abnormal dentition, and an increased risk for cerebrovascular disease and insulin resistance. Biallelic loss-of-function mutations in the pericentrin gene cause MOPDII, which is inherited in an autosomal recessive manner.

Surgical outcomes of Majewski osteodysplastic primordial dwarfism Type II with intracranial vascular anomalies

OBJECTIVE Majewski osteodysplastic primordial dwarfism Type II (MOPD II) is a rare genetic disorder. Features of it include extremely small stature, severe microcephaly, and normal or near-normal intelligence. Previous studies have found that more than 50% of patients with MOPD II have intracranial vascular anomalies, but few successful surgical revascularization or aneurysm-clipping cases have been reported because of the diminutive arteries and narrow surgical corridors in these patients. Here, the authors report on a large series of patients with MOPD II who underwent surgery for an intracranial vascular anomaly. METHODS In conjunction with an approved prospective registry of patients with MOPD II, a prospectively collected institutional surgical database of children with MOPD II and intracranial vascular anomalies who underwent surgery was analyzed retrospectively to establish long-term outcomes. RESULTS Ten patients with MOPD II underwent surgery between 2005 and 2012; 5 patients had moyamoya disease (MMD), 2 had intracranial aneurysms, and 3 had both MMD and aneurysms. Patients presented with transient ischemic attack (TIA) (n = 2), ischemic stroke (n = 2), intraparenchymal hemorrhage from MMD (n = 1), and aneurysmal subarachnoid hemorrhage (n = 1), and 4 were diagnosed on screening. The mean age of the 8 patients with MMD, all of whom underwent extracranial-intracranial revascularization (14 indirect, 1 direct) was 9 years (range 1-17 years). The mean age of the 5 patients with aneurysms was 15.5 years (range 9-18 years). Two patients experienced postoperative complications (1 transient weakness after clipping, 1 femoral thrombosis that required surgical repair). During a mean follow-up of 5.9 years (range 3-10 years), 3 patients died (1 of subarachnoid hemorrhage, 1 of myocardial infarct, and 1 of respiratory failure), and 1 patient had continued TIAs. All of the surviving patients recovered to their neurological baseline. CONCLUSIONS Patients with MMD presented at a younger age than those in whom aneurysms were more prevalent. Microneurosurgery with either intracranial bypass or aneurysm clipping is extremely challenging but feasible at expert centers in patients with MOPD II, and good long-term outcomes are possible.

Mutations in genes encoding condensin complex proteins cause microcephaly through decatenation failure at mitosis

Martin et al. report that biallelic mutations in NCAPD2, NCAPH, or NCAPD3, encoding subunits of condensin complexes, cause microcephaly. Frequent anaphase chromatin bridge formation observed in apical neural progenitors during neurogenesis are the consequence of failed sister chromatid disentanglement during chromosome compaction.

Compaction of chromosomes is essential for accurate segregation of the genome during mitosis. In vertebrates, two condensin complexes ensure timely chromosome condensation, sister chromatid disentanglement, and maintenance of mitotic chromosome structure. Here, we report that biallelic mutations in NCAPD2, NCAPH, or NCAPD3, encoding subunits of these complexes, cause microcephaly. In addition, hypomorphic Ncaph2 mice have significantly reduced brain size, with frequent anaphase chromatin bridge formation observed in apical neural progenitors during neurogenesis. Such DNA bridges also arise in condensin-deficient patient cells, where they are the consequence of failed sister chromatid disentanglement during chromosome compaction. This results in chromosome segregation errors, leading to micronucleus formation and increased aneuploidy in daughter cells. These findings establish “condensinopathies” as microcephalic disorders, with decatenation failure as an additional disease mechanism for microcephaly, implicating mitotic chromosome condensation as a key process ensuring mammalian cerebral cortex size.

Growth charts for individuals with rhizomelic chondrodysplasia punctata

Rhizomelic chondrodysplasia punctata (RCDP) is a class of peroxisomal disorders characterized by defective plasmalogen biosynthesis. There are multiple recognized types of RCDP, all of which have autosomal recessive inheritance, and their associated genes are known: RCDP type 1 with PEX7, RCDP type 2 with GNPAT, RCDP type 3 with AGPS, RCDP type 4 with FAR1, and RCDP type 5 with PEX5. Among other medical/developmental issues, plasmalogen deficiency has a direct effect on bone growth and results in postnatal growth failure, the severity of which corresponds to the degree of plasmalogen deficiency. In order to document growth in patients with RCDP, we present detailed growth curves for length, weight, and head circumference derived from retrospective data from 23 individuals with RCDP types 1 and 2 confirmed by molecular and/or biochemical studies. We stratified growth curves by age as well as by plasmalogen level, with those with higher plasmalogens grouped as "non-classic." The growth charts presented here provide guidance to families and physician caretakers on the natural course of growth in individuals with RCDP during infancy into early childhood, and thus will have particular utility in setting expectations and guiding optimal feeding interventions in this population.© 2016 Wiley Periodicals, Inc.