Interstitial deletions at 6q14.1q15 associated with developmental delay and a marfanoid phenotype

There are a number of reports of interstitial deletions of the long arm of chromosome 6 that have developmental delay and obesity suggesting that this is a distinct phenotype almost like Prader-Willi syndrome. Here we report a patient with a similar deletion but a strikingly different phenotype, one more in keeping with Marfan syndrome, although he does not fulfil the criteria for that syndrome. Array comparative genomic hybridization was performed to investigate a patient with a striking phenotype. This revealed an interstitial deletion of 6q14.1q15. Parental FISH studies were normal, indicating that this is a de novo deletion. Our patient has a completely different phenotype compared to other patients reported to have similar deletions. The common feature is developmental delay, but the body features are quite different in that our patient is tall, strikingly thin with pectus excavatum, scoliosis, skin striae, arachnodactyly, pes planus, cataracts, and a high-arched palate. This contrasts with other patients who have a similar deletion but have short stature and obesity. 6q14.1q15 interstitial deletions can have a very variable phenotype and do not necessarily conform to a clinical recognizable microdeletion syndrome caused by haploinsufficiency of dosage-sensitive genes in that region as proposed by others.

Co-occurrence of Joubert syndrome and Jeune asphyxiating thoracic dystrophy

Ciliary disorders share typical features, such as polydactyly, renal and biliary cystic dysplasia, and retinitis pigmentosa, which often overlap across diagnostic entities. We report on two siblings of consanguineous parents and two unrelated children, both of unrelated parents, with co-occurrence of Joubert syndrome and Jeune asphyxiating thoracic dystrophy, an association that adds to the observation of common final patterns of malformations in ciliary disorders. Using homozygosity mapping in the siblings, we were able to exclude all known genes/loci for both syndromes except for INVS, AHI1, and three genes from the previously described Jeune locus at 15q13. No pathogenic variants were found in these genes by direct sequencing. In the third child reported, sequencing of RPGRIP1L, ARL13B, AHI1, TMEM67, OFD1, CC2D2A, and deletion analysis of NPHP1 showed no mutations. Although this study failed to identify a mutation in the patients tested, the co-occurrence of Joubert and Jeune syndromes is likely to represent a distinct entity caused by mutations in a yet to be discovered gene. The mechanisms by which certain organ systems are affected more than others in the spectrum of ciliary diseases remain largely unknown.

FOXL2 copy number changes in the molecular pathogenesis of BPES: unique cohort of 17 deletions

Blepharophimosis Syndrome (BPES) is an autosomal dominant developmental disorder of the eyelids with or without ovarian dysfunction caused by FOXL2 mutations. Overall, FOXL2deletions represent 12% of all genetic defects in BPES. Here, we have identified and characterized 16 new and one known FOXL2 deletion combining multiplex ligation-dependent probe amplification (MLPA), custom-made quantitative PCR (qPCR) and/or microarray-based copy number screening. The deletion breakpoints could be localized for 13 out of 17 deletions. The deletion size is highly variable (29.8 kb - 11.5 Mb), indicating absence of a recombination hotspot. Although the heterogeneity of their size and breakpoints is not reflected in the uniform BPES phenotype, there is considerable phenotypic variability regarding associated clinical findings including psychomotor retardation (8/17), microcephaly (6/17), and subtle skeletal features (2/17). In addition, in all females in whom ovarian function could be assessed, FOXL2 deletions proved to be associated with variable degrees of ovarian dysfunction. In conclusion, we present the largest series of BPES patients with FOXL2 deletions and standardized phenotyping reported so far. Our genotype-phenotype data can be useful for providing a prognosis (i.e. occurrence of associated features) in newborns with BPES carrying a FOXL2 deletion.

Overlap between Rubinstein-Taybi and Saethre-Chotzen syndromes: a case report

This report concerns a 14-year follow-up of a patient whose clinical manifestations led to a diagnosis of Rubinstein-Taybi syndrome; however, his intelligence is normal. Reappraisal resulted in a change of diagnosis to Saethre-Chotzen syndrome. Overlapping manifestations in the 2 syndromes are discussed.

Bowen-Conradi syndrome: a clinical and genetic study

The purpose of the study was to delineate the anomalies and the natural life history of persons with the Bowen-Conradi syndrome [Bowen and Conradi 1976: Birth Defects: Orig Artic Ser XII(6):101-108]. We ascertained 39 cases and personally examined almost all. For those who were not seen, their clinical record were scrutinized. Pedigree analysis of all 39 was done and kinship coefficients computed. The birth prevalence was estimated to be 1/355 live births.

Association between congenital foot anomalies and gestational age at amniocentesis

OBJECTIVES

Our objectives were to confirm the reported association between early amniocentesis and congenital foot anomalies as well as to report, for the first time, on the outcome of amniocenteses performed during the 13th and 14th weeks of gestation.

METHODS

We conducted a triple cohort retrospective study of 4457 amniocenteses. Cohort definitions: early amniocentesis (EA), 11 weeks and 0/7 days to 12 weeks to 6/7 days; early midtrimester amniocentesis (EMA), 13 weeks and 0/7 days to 14 weeks and 6/7 days; and midtrimester amniocentesis (MA), 15 weeks and 0/7 days to 19 weeks and 6/7 days. Outcome measures were obtained by searching the Alberta Congenital Anomalies Surveillance System (ACASS) database for children born with foot anomalies represented by International Classification of Diseases version 9 (ICD-9) codes 754.5, 754.6 and 754.7.

RESULTS

Incidences of congenital foot anomalies were: EA 11/980 (1.1%), EMA 11/2515 (0.4%), and MA 1/962 (0.1%). There is a significant difference between the EA and EMA cohorts (p=0.019) and between the EA and MA cohorts (p=0.003); however, these data suggest there is no difference between EMA and MA cohorts (p=0.11).

CONCLUSIONS

Our incidence of congenital foot anomalies of 1.1% for women who underwent EA is similar to previously reported data, which further validates this association; however, our data also suggest that the foot anomaly risk may be limited to amniocenteses performed before the 13th week of gestation.

Syndrome of coronal craniosynostosis, Klippel-Feil anomaly, and sprengel shoulder with and without Pro250Arg mutation in the FGFR3 gene

A unique Pro250Arg point mutation in fibroblast growth factor receptor 3 (FGFR3) was initially reported by Bellus et al. [1996: Nat Genet 14:174-176] and the phenotype subsequently by Muenke et al. [1997: Am J Hum Genet 60:555-564], Reardon et al. [1997: J Med Genet 34:632-636], and Graham et al. [1998: Am J Med Genet 77:322-329]. These authors emphasized the pleiotropic nature of this form of coronal craniosynostosis, including brachydactyly with carpal and/or tarsal coalitions, with other anomalies at lower frequency. We report on a family with autosomal dominant coronal synostosis, segmentation and fusion anomalies of the vertebra and ribs, and Sprengel shoulder due to the Pro250Arg mutation. We also report a single case with an identical phenotype without the mutation.

Completeness and accuracy of the birth registry data on congenital anomalies in Alberta, Canada

Vital statistics and other administrative data are becoming an increasingly important source for epidemiologic research and surveillance. This study, the first in Canada, evaluated the usefulness of birth registry data on congenital anomalies in Alberta. We compared the number of birth defects recorded in the birth registry with the number collected through the Alberta Congenital Anomalies Surveillance System (ACASS) between 1985 and 1996. In addition, records of 3,881 (99.9 %) babies with (a) birth defect(s) from the ACASS during 1994--1996 were matched to the birth registry by deterministic linkage. Of these, 2,969 babies had single anomalies that were used for validity analysis. The anomalies were grouped by those within International Classification of Disease (ICD) ICD-9 Section XIV (ICD-9=740.0-759.9) and those outside the Section XIV. For those within Section XIV, 24 summary diagnostic categories were examined. As shown, the total case count from the birth registry was on average about 3 % lower than that from the ACASS between 1985 and 1996. The validity of diagnostic categories is high for the 24 categories examined, with an overall agreement of between 80 % and 100 %. The sensitivity, positive predictive value, and kappa are also high for all these anomalies combined during 1994 and 1996, showing 95.7 %, 99.8, and 0.81 respectively.

Mutations in the novel protocadherin PCDH15 cause Usher syndrome type 1F

We have determined the molecular basis for Usher syndrome type 1F (USH1F) in two families segregating for this type of syndromic deafness. By fluorescence in situ hybridization, we placed the human homolog of the mouse protocadherin Pcdh15 in the linkage interval defined by the USH1F locus. We determined the genomic structure of this novel protocadherin, and found a single-base deletion in exon 10 in one USH1F family and a nonsense mutation in exon 2 in the second. Consistent with the phenotypes observed in these families, we demonstrated expression of PCDH15 in the retina and cochlea by RT-PCR and immunohistochemistry. This report shows that protocadherins are essential for maintenance of normal retinal and cochlear function.

Two brothers with severe developmental delay, growth retardation and unusual appearance

We report on two brothers with short stature, severe developmental delay and unusual appearance. Several conditions including the Russell-Silver, Dubowitz, Floating-Harbour and Cockayne syndromes were considered in the differential diagnosis, but subsequently rejected. These two cases are likely to represent a new autosomal recessive or X-linked recessive syndrome.

Characterization of an interstitial deletion del(13)(q22q32) using microdissection and sequential FISH and G-banding

The objective of this study was to delineate a chromosome 13 abnormality and establish its clinical correlation by using molecular cytogenetics procedures. A newborn boy presented with clinical findings, including mild symmetric intrauterine growth retardation (IUGR), small ears with thickened helices, a scalp lesion, short fifth fingers, missing toes, and talipes equinovarus. Routine G-banding of cultured peripheral blood cells revealed that the patient had one abnormal and shortened chromosome 13, but uncertainty remained as to whether the abnormality was the result of an interstitial deletion or a translocation. Thirteen copies of G-banded abnormal chromosomes 13 were isolated with microdissection and amplified with PCR using degenerate oligonucleotide primers. Fluorescence in situ hybridization (FISH) of the PCR product to normal metaphases showed one pair of acrocentrics hybridized, more or less uniformly, along the length of the long arm with an unhybridized gap in the distal region, indicative of an interstitial deletion. Sequential FISH and G-banding of the same chromosome preparations conclusively demonstrated that the deleted segment was 13q22-q32. Four cases of del(13)(q22q32) have been previously reported. The common findings in all five cases, including the present one, are psychomotor and growth retardation, as well as hand and foot anomalies.

Congenital anomalies ascertained by two record systems run in parallel in the Canadian Province of Alberta

To assess the quality and appropriateness of Canadian Congenital Anomalies Surveillance System (CCASS), a system based on routine hospital admission/separation records, we compared the congenital anomalies ascertained by CCASS for the period of January 1, 1990 to December 31, 1993 in the province of Alberta with corresponding figures obtained from Alberta Congenital Anomalies Surveillance System (ACASS), a specific-purpose surveillance program collecting information on congenital anomalies from multiple sources with mechanisms to evaluate diagnosis. Rates of congenital anomalies estimated by CCASS tended to be higher. Agreement between CCASS and ACASS depended on diagnosis: for the International Clearinghouse for Birth Defects Monitoring System standard categories of congenital anomalies (except for anomalies of abdominal wall), agreement usually exceeded 50%; for less clear-cut diagnoses, it was well below 50%. We conclude that routine medical records can be used for surveillance purposes for major congenital anomalies with clear-cut diagnosis.

Incidence of inborn errors of metabolism in British Columbia, 1969-1996

OBJECTIVE

To determine how many children with specific types of inborn errors of metabolism are born each year in British Columbia, Canada. This population provides a relatively unique setting for collection of accurate and uniform incidence data because the diagnoses are all made through one laboratory in a population with universal access to government-funded medical care.

METHODOLOGY

We used the records of the Biochemical Diseases Laboratory, Children's Hospital, Vancouver (the central referral point for all metabolic diagnoses in British Columbia) to identify all patients diagnosed with the metabolic diseases defined below. We obtained incidence figures by including only the children diagnosed with the diseases covered in this article who were confirmed as having been born within the province for the years 1969 to 1996. The diseases covered were diseases of amino acids, organic acids, the urea cycle, galactosemia, primary lactic acidoses, glycogen storage diseases, lysosomal storage diseases, and diseases involving specifically peroxisomal and mitochondrial respiratory chain dysfunction. Because the technology needed for diagnosis of specific disease groups was in place at different times our data for the different disease groups correspond to different time frames. We have also adjusted the time frames used to allow for the likelihood that some diseases may not come to medical attention for some time after birth. For instance the incidence of amino acid diseases was assessed throughout the whole of this time frame but the incidence of peroxisomal diseases was restricted to 1984 to 1996 because this was the time frame during which the technology needed for diagnosis was in place and reliable. Most disease group statistics included at least 400 000 births.

RESULTS

The overall minimum incidence of the metabolic diseases surveyed in children born in British Columbia is approximately 40 cases per 100 000 live births. This includes phenylketonuria (PKU) and galactosemia which are detected by a newborn screening program. Metabolic diseases, which were not screened for at birth, ie, those with PKU and galactosemia subtracted from the total, have a minimal incidence of approximately 30 cases per 100 000 live births. This diagnostic dilemma group would present to pediatricians for diagnosis. Not all metabolic diseases have been surveyed and our data are restricted to the following metabolic disease groups. Approximately 24 children per 100 000 births (approximately 60% of the total disease groups surveyed) have a disease involving amino acids (including PKU), organic acids, primary lactic acidosis, galactosemia, or a urea cycle disease. These children all have metabolic diseases involving small molecules. Approximately 2.3 children per 100 000 births ( approximately 5%) have some form of glycogen storage disease. Approximately 8 per 100 000 births (20%) have a lysosomal storage disease; approximately 3 per 100 000 births (7%-8%) have a respiratory chain-based, mitochondrial disease and approximately 3 to 4 per 100 000 (7%-8%) of births have a peroxisomal disease. The diseases involving subcellular organelles represent approximately half of the diagnostic dilemma group. The incidence of each of the specific diseases diagnosed, including apparently rare diseases such as nonketotic hyperglycinemia, is to be found in the text. The metabolic diseases reported in this survey represent over 10% of the total number of single gene disorders in our population.

CONCLUSIONS

Our data provide a good estimate of metabolic disease incidence, for the disease groups surveyed, in a predominantly Caucasian population. Incidence data for metabolic diseases are hard to collect because in very few centers are diagnoses centralized for a population with uniform access to modern health care and this has been the case for our population during the course of the study. (ABSTRACT TRUNCATED)

Congenital autosomal dominant distal spinal muscular atrophy

We present a father and son with congenital foot deformity. The father at age 41 years used crutches and the son at 7 years walked unaided. Both had atrophy and weakness of lower leg muscles and mild proximal and hand intrinsic weakness. Knee and ankle myotactic reflexes were absent and sensation was intact. Creatine kinase level was normal, nerve conduction studies wer normal and electromyography showed chronic neurogenic change. In both, nerve biopsies were normal and muscle biopsies showed type 1 predominance. The boy's serum hexosaminidase, spinal MRI and SMN gene were normal. This may be the first well documented example of congenital autosomal dominant distal spinal muscular atrophy affecting legs and arms.

Syndrome of multiple epiphyseal dysplasia (ribbing type) with rhizomelic shortness, cleft palate, and micrognathia in two unrelated patients

We report on two unrelated patients with an apparently new syndrome. In each family they are the only affected members, their parents are not consanguineous, and paternal and maternal ages are not advanced. At birth each patient was noted to have a marked Robin phenotype (cleft of the secondary palate and micrognathia) plus rhizomelic shortness. Delay in the appearance of long bone epiphyses was noted and followed by small fragmented and later very flat epiphyses of all long bones. The fibulae are short and radial heads dislocated. Scoliosis and marked genu valgum developed in both. Both patients have normal intelligence, vision, and hearing. Both have mildly upward slanting palpebral fissures, broad nasal tip, and apparent hypertelorism.

Autosomal recessive, fatal infantile hypertonic muscular dystrophy among Canadian Natives

We describe eleven mid-western Canadian aboriginal infants with a unique, progressive muscle disorder. All except one had muscle biopsy and/or autopsy. The infants were normal newborns who rapidly developed rigidity of all skeletal muscles, with early, respiratory insufficiency. Death occurred before 18 months of age. Electromyography showed increased insertion activity and profuse fibrillation potentials; motor unit potentials and interference pattern are normal until late in the course. Pathologic features include progressive, granular to powdery Z-band transformation, myofibrillar loss, and muscle regeneration. SDS-gel electrophoresis of one muscle sample revealed increased 54kDa and reduced 80kDa protein fractions. This disease differs from other conditions with Z-band alterations because of continuous muscle activity and relentless clinical progression. The clinical features, elevated serum creatine kinase, electromyographic and muscle biopsy findings suggest a dystrophic process. The recognition of this condition as an autosomal recessive disorder allows appropriate genetic counselling.

X-linked recessive nephritis with mental retardation, sensorineural hearing loss, and macrocephaly

A family with hereditary nephritis, sensorineural hearing loss, macrocephaly, and mental retardation is reported. X-linked recessive inheritance was suggested by the presence of two affected brothers and a maternal uncle. This association may be a previously unreported variant of Alport's syndrome.

Analysis of sperm chromosome complements from a man heterozygous for a pericentric inversion of chromosome 1

Human sperm chromosomes were studied in a man heterozygous for a pericentric inversion of chromosome (1)(p31q12). Q-banded pronuclear chromosomes were analyzed after in vitro penetration of golden hamster oocytes. A total of 159 sperm were examined: 54% bearing the inverted chromosome 1 and 46% the normal chromosome 1. These frequencies are not significantly different from the theoretical 1:1 ratio. There were no recombinant sperm with duplications or deficiencies, suggesting that a pairing loop failed to form or that crossing-over was suppressed. The frequency of abnormalities unrelated to the inversion was 5% for numerical, 8.8% for structural, 2.5% for numerical and structural, values not significantly different from control donors studied in our lab. The frequencies of X- and Y-bearing sperm were 46% and 54%, respectively, not significantly different from the expected value of 50%. This is the fifth pericentric inversion studied by human sperm chromosome analysis; recombinant chromosomes have been observed in two of the five cases. Some of the factors associated with an increased risk of recombinant sperm appear to be inversion size greater than 30% of the chromosome and chromosome breakpoints in G-light bands.

Absent fibula and craniosynostosis: a 25 year follow up

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Familial complex chromosomal rearrangement resulting in duplication/deletion of 6q14 to 6q16

A familial complex chromosomal rearrangement (CCR) was ascertained through a mentally retarded, dysmorphic individual. Carriers of the CCR have the karyotype 46,XX or XY, t(6;15)(q16;q21), ins(3;6)(q12;q14q16), and malsegregation of the CCR resulted in loss of the segment 6q14 to 6q16 in the proband, and in an additional copy of the same segment in three members of the extended family. The proband has features similar to other reported cases with deletion of 6q1. The individuals with duplication of 6q14 to 6q16 have moderate mental retardation, short stature, obesity, microcephaly, brachycephaly, a short smooth philtrum, central hair whorl, simian creases, 5th finger brachydactyly and skeletal disproportion. In the 4-generation family, CCR carriers have a 20% empiric risk of phenotypically abnormal livebirths.

Cleft lip and palate, sensorineural deafness, and sacral lipoma in two brothers: a possible example of the disorganisation mutant

We report two brothers of Chinese origin who have an apparently unique syndrome of cleft lip/palate, profound sensorineural deafness, and a sacral lipoma. Additional findings which were not common to both were aberrant digital appendages on the heel and thigh of one boy and an anterior sacral meningocele and dislocated hip in the other. Intelligence is normal in both. Both boys suffer from functional constipation but biopsy studies showed no evidence of Hirschsprung's disease. The parents, who are normal, are not related. Inheritance is probably autosomal or X linked recessive. A possible link with the disorganisation mouse mutant is discussed.

The Alberta Hereditary Diseases Program: a regional model for delivery of genetic services

Genetic counselling and related services are generally provided at major university medical centres because they are very specialized. The need for rurally based genetic services prompted the inclusion of an outreached program in the Alberta Hereditary Diseases Program (AHDP), which was established in 1979; the AHDP was designed to provide services to the entire province through two regional centres and seven outreach clinics. There is a community health nurse in almost every health unit whose duties are either totally or partially devoted to the AHDP; thus, genetic help and information are as close as a rural health unit. The AHDP is designed to provide complete clinical (diagnostic, counselling and some management) services and laboratory (cytogenetic, biochemical and molecular) services for genetic disorders. In addition, the program emphasizes education and publishes a quarterly bulletin, which is sent free of charge to all physicians, hospitals, public health units, social service units, major radio and television stations, newspapers and public libraries and to selected individuals and groups in Alberta.

Alberta Congenital Anomalies Surveillance System

The Alberta Congenital Anomalies Surveillance System was started in 1966 in response to the thalidomide tragedy earlier in the decade. It was one of four provincial surveillance systems on which the federal government relied for baseline statistics of congenital anomalies. The government now collects data from six provinces and one territory. The Alberta Congenital Anomaly Surveillance System originally depended on three types of notification to the Division of Vital Statistics, Department of Health, Government of Alberta: birth notice and certificates of death and stillbirth; increased sources of ascertainment have greatly improved data quality. We present the data for 1980-86 and compare the prevalence rates of selected anomalies with the rates from three other surveillance systems. Surveillance systems do not guarantee that a new teratogen will be detected, but they are extremely valuable for testing hypotheses regarding causation. At the very least they provide baseline data with which to compare any deviation or trend. For many, if not most, congenital anomalies total prevention is not possible; however, surveillance systems can be used to measure progress in prevention.

Epiphyseal dysplasia, microcephaly, nystagmus, and retinitis pigmentosa

In 1975, we reported two brothers with epiphyseal dysplasia, microcephaly, and nystagmus; one of them also had mild mental retardation. Here we present information on the natural history, particularly with respect to the development of a new visual problem, namely, retinitis pigmentosa.

Birth prevalence of cleft lip and palate in British Columbia between 1952 and 1986: stability of rates

We examined the birth prevalence of cleft lip with or without cleft palate and of isolated cleft palate in British Columbia between 1952 and 1986 using the data of the BC Health Surveillance Registry. The rates fluctuated over the study period, but linear trend analysis showed no increase or decrease for cleft lip with or without cleft palate; however, there was a significant increase for isolated cleft palate, attributed to improved ascertainment around 1963-66. Given the possible effects of newer agents used in both silviculture and agriculture, as well as the general concern over drugs and other environmental agents, such a long-term monitoring program is important. Furthermore, if significant clustering occurs, good background data are essential for comparison. The general public's perception is that the rates of birth defects are increasing. Our findings should give some reassurance with respect to orofacial clefts.

An interstitial deletion of the long arm of chromosome 13

A case of an interstitial deletion of chromosome 13, identified as 46,XY,del(13)(q22q31), is reported in a child with psychomotor retardation, prominent low-set ears, epicanthus, hypertelorism, broad nasal bridge, hypoplastic fifth fingers and abnormal dermatoglyphics. This patient is compared to others in the literature with a similar deletion.

Mental retardation, distinct facial changes, short stature, obesity, and hypogonadism: a new X-linked mental retardation syndrome

We describe a 3-year-old boy and his 2 maternal uncles with moderate to severe mental retardation, short stature, mild obesity, hypogonadism, a low total finger ridge count, and a distinctive face characterized by bitemporal narrowness, almond-shaped palperbral fissures, depressed nasal bridge, anteverted nares, short and inverted-V-shaped upper lip, and macrostomia. Two other males in this family who had similar facial anomalies and developmental delay died in early infancy and midchildhood. This apparently new disorder is reminiscent of, but distinct from, the Prader-Willi syndrome, and is likely inherited as an X-linked recessive trait. Preliminary studies with DNA probes are consistent with an X-linked locus and permit exclusion of distal Xp and Xq regions as the site of this mutation.

Birth prevalence and recurrence rates of neural tube defects in southern Alberta in 1970-81

Given the observed variation in birth prevalence and recurrence rates of neural tube defects, it is important to obtain such data specific to a given locality for research and genetic counseling purposes. A review of hospital medical charts, the patient lists of the Medical Genetics and Myelomeningocele clinics at Alberta Children's Hospital and data from the Canadian Congenital Anomalies Surveillance System revealed the annual birth prevalence rate of neural tube defects in southern Alberta in 1970-81 to be 1.62/1000 total births. This figure suggests southern Alberta to be a low-frequency area. There was no significant variation in the annual rates of spina bifida, encephalocele or all neural tube defects combined over the study period. A significant linear decline in the frequency of births of anencephalic infants, however, was noted (p = 0.025). Information on the total reproductive history of the mothers revealed that the empiric risk of recurrence of a neural tube defect was 2.2%, and the risk to all siblings was estimated to be 2.3%. In future prevalence studies multiple sources of case ascertainment should be used, including data on pregnancies terminated because of a fetal neural tube defect.

Genetic disorders in children and young adults: a population study

The data base of an ongoing population-based registry with multiple sources of ascertainment was used to estimate the present population load from genetic disease in more than 1 million consecutive live births. It was found that, before approximately age 25 years, greater than or equal to 53/1,000 live-born individuals can be expected to have diseases with an important genetic component. This total was composed of single-gene disorders (3.6/1,000), consisting of autosomal dominant (1.4/1,000), autosomal recessive (1.7/1,000), and X-linked recessive disorders (0.5/1,000). Chromosomal anomalies accounted for 1.8/1,000, multifactorial disorders (including those present at birth and those of onset before age 25 years) accounted for 46.4/1,000, and cases of genetic etiology in which the precise mechanism was not identified accounted for 1.2/1,000. Previous studies have usually considered all congenital anomalies (ICD 740-759) as part of the genetic load, but only those judged to fit into one of the above categories were included in the present study. Data for congenital anomalies are therefore also presented separately, to facilitate comparison with earlier studies. If all congenital anomalies are considered as part of the genetic load, then greater than or equal to 79/1,000 live-born individuals have been identified as having one or other genetic disorder before approximately age 25 years. These new data represent a better estimate of the genetic load in the population than do previous studies.

Genetics in pediatrics

The prevalence of genetic disease in the pediatric population is considerable and probably accounts for at least 50% of childhood deaths and 25% of hospital pediatric admissions. A simple three-generation family history is often very useful, as is background information on ethnicity and consanguinity. A preponderance of affected males in a family should immediately suggest an X-linked recessive disorder which may have widespread implications for female relatives in the family. Chromosomal errors will usually be associated with developmental handicaps and one or more major or minor dysmorphic signs. Disorders involving secondary sexual characteristics are largely genetic in origin. Many disorders which were previously thought to be one entity are now known to be many different entities (genetic heterogeneity).

Autosomal recessive juvenile cataract in Hutterites

Autosomal recessive inheritance of juvenile cataract is described amongst several related sibships of Lehrerleut Hutterites. The main features of the cataract include onset between three and seven years of age; rapid progression to maturity within one to three months; normal intelligence; no systemic associations, and no urinary reducing substances and normal erythrocyte galactokinase activity. Genetic analysis demonstrates the close relationship between parents of affected sibships with a coefficient of inbreeding of affected sibships of 0.0512. Estimates of heterozygote frequency within Lehrerleut Hutterites at 0.128 indicate that if current inbreeding practice continues additional cases can be expected.

Keutel syndrome: clinical report and literature review

In 1972 Keutel et al described a brother and sister with brachytelephalangism, hearing loss, peripheral pulmonary stenosis and abnormal cartilage calcification. Since then, three additional cases have been reported. We report a sixth case and discuss the clinical findings and cause.

The Grant syndrome. Persistent Wormian bones, blue sclerae, mandibular hypoplasia, shallow glenoid fossae and campomelia--an autosomal dominant trait

A father and daughter with apparently unique clinical findings are described. The findings include persistent Wormian bones, blue sclerae, mandibular hypoplasia, shallow glenoid fossae and campomelia. Apparently it is an autosomal dominant trait. Although the disorder is in the osteogenesis imperfecta group, nevertheless it appears to be different and until the basic defect is found we have named it "The Grant Syndrome".

Congenital anomalies in American Indians of British Columbia

Birth prevalences of congenital anomalies in the American Indians of British Columbia are compared with those of the total British Columbia population. This study is based on data from the British Columbia Health Surveillance Registry for a 16-year period (1966-1981) judged to be the most reliable reporting period in the 35-year history of the registry. The overall congenital anomaly frequency is lower in Indians than in the general population (45 versus 60 per 1,000 livebirths). The Indian rates for individual anomalies are lower than the corresponding general population rates with the exception of orofacial clefting and congenital heart defects. Defects of the central nervous system in both populations are comparable. There is a striking paucity of hypospadias, other anomalies of the genital organs and foot deformities in Indian males. It is suggested that the differences in the congenital anomaly rates between the American Indians and the non-Indians of British Columbia may reflect genetic differences between the two groups, but differences in ascertainment and infant mortality probably also play a role.

Congenital contractures, edema, hyperkeratosis, and intrauterine growth retardation: a fatal syndrome in Hutterite and Mennonite kindreds

We present clinical findings in infants from three kindreds (two Hutterite and one Mennonite) with an apparently unique, fatal disorder. The major manifestations consist of severe intrauterine growth retardation, congenital contractures, and tense skin which is easily eroded. The skin is tightly drawn over the face, giving an abnormal appearance consisting of a narrow, pinched nose, small mouth, limited jaw mobility, and ectropion (in one). One infant had first-degree hypospadias. Apart from this, there were no organ malformations and the infants did not have hydrops. Histologically, the skin showed hyperkeratosis. It is postulated that this is a tissue dysplasia and that all of the clinical effects are secondary. The disorder appears to be an autosomal recessive trait. The two Hutterite families are from different endogamous subdivisions. They are related as fourth cousins once-removed and fifth cousins in multiple ways through the six nearest common ancestors of all four parents. There are 25 founders (11 couples and three individuals) who are common ancestors. We computed the probability of joint descent of the four alleles in each pair of parents and in a sample of Alberta Hutterite couples, assuming that each of the common founders in turn was the original carrier. For an allele from one particular founder couple, there is a relatively greater probability of identity by descent for each pair of parents than on the average for other couples of the same endogamous subdivision.

Congenital anomalies in the Hutterite population: a preliminary survey and hypothesis

The Alberta Provincial Congenital Anomaly (CA) Surveillance reporting forms were scanned for infants whose surnames and addresses identified them as belonging to the Hutterite Brethren. Death registrations (of infants up to 1 year) and stillbirth registrations were similarly scanned. While the overall percentage of total malformations (5%) and major malformations (2%) was no different from that of the total population of Alberta, closer examination of the actual entities showed a large number of monogenic disorders among the Hutterites. The frequency of multifactorial congenital anomalies was approximately 1%. The inbreeding coefficients, using a genealogic data base, were computed for each "case baby" and two Hutterite "control babies," the latter being births preceding and succeeding the case baby. There was no statistical difference in the distribution of inbreeding coefficients between the case and control groups. While the data are based on small numbers and therefore are preliminary, they suggest that the Hutterite lifestyle, of good nutrition (using largely home prepared foods), absence of tobacco and minimal alcohol consumption, may be one factor responsible for fewer multifactorial CAs whose occurrence is environmentally susceptible to such influences. Studies of populations with a low incidence of disorders are just as important as those with a high incidence.

Hutterite cerebro-osteo-nephrodysplasia: autosomal recessive trait in a Lehrerleut Hutterite family from Montana

We are reporting on two Lehrerleut Hutterite sisters who have a syndrome of congenital shortness with mild spondylorhizomelic dwarfism; later failure to thrive, ie deceleration of weight gain presumably due to CNS-based severe feeding problems; a CNS defect, probably developmental (not biochemical) with normal prenatal brain growth but later deceleration from 50th to 2nd centile associated with severe mental retardation and decorticate disturbances of neurologic function; and possible renal involvement with terminal nephrotic syndrome. This seems to be a previously undescribed pleiotropic autosomal recessive trait.

Mandibulofacial dysostosis in Hutterite sibs: a possible recessive trait

We report on two sisters with mandibulofacial dysostosis (MFD). Both parents were examined carefully by clinical, radiographic, audiologic, and cephalometric methods. Neither showed evidence of the MFD gene. Photographs of three grandparents and examination of one disclosed no evidence of MFD. The parents are from the Hutterite Brethren and are consanguineous. Examination of the literature on MFD disclosed a number of other families with affected sibs and apparently normal parents. These families raise the possibility of an autosomal recessive form of MFD or some other explanation such as germinal mosaicism, chromosome rearrangement, or delayed mutation. For our family, the recurrence risk is probably 25%, but since germinal mosaicism cannot be excluded, it could be as high as 50%.