Mandibulofacial Dysostosis with Microcephaly: Mutation and Database Update

Mandibulofacial dysostosis with microcephaly (MFDM) is a multiple malformation syndrome comprising microcephaly, craniofacial anomalies, hearing loss, dysmorphic features, and, in some cases, esophageal atresia. Haploinsufficiency of a spliceosomal GTPase, U5-116 kDa/EFTUD2, is responsible. Here, we review the molecular basis of MFDM in the 69 individuals described to date, and report mutations in 38 new individuals, bringing the total number of reported individuals to 107 individuals from 94 kindreds. Pathogenic EFTUD2 variants comprise 76 distinct mutations and seven microdeletions. Among point mutations, missense substitutions are infrequent (14 out of 76; 18%) relative to stop-gain (29 out of 76; 38%), and splicing (33 out of 76; 43%) mutations. Where known, mutation origin was de novo in 48 out of 64 individuals (75%), dominantly inherited in 12 out of 64 (19%), and due to proven germline mosaicism in four out of 64 (6%). Highly penetrant clinical features include, microcephaly, first and second arch craniofacial malformations, and hearing loss; esophageal atresia is present in an estimated ∼27%. Microcephaly is virtually universal in childhood, with some adults exhibiting late "catch-up" growth and normocephaly at maturity. Occasionally reported anomalies, include vestibular and ossicular malformations, reduced mouth opening, atrophy of cerebral white matter, structural brain malformations, and epibulbar dermoid. All reported EFTUD2 mutations can be found in the EFTUD2 mutation database (http://databases.lovd.nl/shared/genes/EFTUD2).

Expanding the Molecular and Clinical Phenotype of SSR4-CDG

Congenital disorders of glycosylation (CDG) are a group of mostly autosomal recessive disorders primarily characterized by neurological abnormalities. Recently, we described a single CDG patient with a de novo mutation in the X-linked gene, Signal Sequence Receptor 4 (SSR4). We performed whole-exome sequencing to identify causal variants in several affected individuals who had either an undifferentiated neurological disorder or unsolved CDG of unknown etiology based on abnormal transferrin glycosylation. We now report eight affected males with either de novo (4) or inherited (4) loss of function mutations in SSR4. Western blot analysis revealed that the mutations caused a complete loss of SSR4 protein. In nearly all cases, the abnormal glycosylation of serum transferrin was only slightly above the accepted normal cutoff range.

Descriptive epidemiology of birth defects thought to arise by new mutation

BACKGROUND

The current study is the first to examine the association of a broad range of sociodemographic factors with conditions thought to arise most of the time by de novo mutation.

METHODS

Data were taken from 1999 to 2009 from the Texas Birth Defects Registry (TBDR), a statewide active surveillance program. We used Poisson regression to generate crude and adjusted measures of association; the latter included models with all variables and with a parsimonious subset of variables.

RESULTS

There were 1694 cases with any of the phenotypes in the panel, 1100 cases in a subpanel with ≥90% of cases thought to arise de novo, 523 with chromosomal deletion disorders, and 243 with imprinting disorders. In the most parsimonious models, there was an increasing time trend in all groups except imprinting (p ≤ 0.01). Plurality (twins, triplets, etc.) was associated with greater risk of all groups except chromosomal deletions (p ≤ 0.01). Parental age showed strong trends with all groups; paternal age was most important for the total and imprinting groups (p ≤ 0.0001), and maternal age for the others (p ≤ 0.04). De novo mutation phenotypes were more prevalent among offspring of fathers who are non-Hispanic White compared with some other race/ethnic groups.

CONCLUSION

This study suggests that birth defects arising by new mutation may be more prevalent among offspring of older parents and in plural births. The increasing time pattern and race/ethnic pattern may be related to greater use of or access to genetic tests. This approach to mutation epidemiology seems feasible for birth defects registries to consider.

The Xolair Pregnancy Registry (EXPECT): the safety of omalizumab use during pregnancy

BACKGROUND

For many asthma medications, pregnancy safety data remains insufficient.

OBJECTIVE

The omalizumab pregnancy registry, EXPECT, evaluates maternal, pregnancy, and infant outcomes after exposure to omalizumab, including incidence of congenital anomalies.

METHODS

EXPECT is a prospective, observational study of pregnant women exposed to ≥1 dose of omalizumab within 8 weeks prior to conception or at any time during pregnancy. Primary outcome measures include rates of live births, elective terminations, stillbirths, and congenital anomalies. Data were collected at enrollment, each trimester, birth, and every 6 months up to 18 months post-delivery.

RESULTS

As of November 2012, 188 of 191 pregnant women were exposed to omalizumab during their first trimester. Of 169 pregnancies with known outcomes (median exposure during pregnancy, 8.8 months), there were 156 live births of 160 infants (4 twin pairs), 1 fetal death/stillbirth, 11 spontaneous abortions, and 1 elective termination. Among 152 singleton infants, 22 (14.5%) were born prematurely. Of 147 singleton infants with weight data, 16 (10.9%) were small for gestational age. Among 125 singleton full-term infants, 4 (3.2%) had low birth weights. Overall, 20 infants had congenital anomalies confirmed, 7 (4.4%) of whom had 1 major defect. No pattern of anomalies was observed.

CONCLUSIONS

To date, proportions of major congenital anomalies, prematurity, low birth weight, and small size for gestational age observed in the EXPECT registry are not inconsistent with findings from other studies in this asthma population. Recognizing the small sample size available, no apparent increased birth prevalence of major anomalies or patterns of major anomalies has been observed.

Sociodemographic and hispanic acculturation factors and isolated anotia/microtia

BACKGROUND

It has been observed in several studies that infants with anotia/microtia are more common among Hispanics compared with other racial/ethnic groups. We examined the association between selected Hispanic ethnicity and acculturation factors and anotia/microtia in the National Birth Defects Prevention Study.

METHODS

We examined data from mothers of 351 infants with isolated anotia/microtia and 8435 unaffected infants from the National Birth Defects Prevention Study with an expected delivery date from 1997 to 2007. Sociodemographic, maternal, and acculturation factors (e.g., age, maternal education, household income, body mass index, gestational diabetes, folic acid, smoking, alcohol intake, study center, parental birthplace, and years lived in the United States, maternal language) were assessed as overall risk factors and also as risk factors among subgroups of Hispanics (United States- and foreign-born) versus non-Hispanic whites.

RESULTS

Compared with non-Hispanic whites, both United States- and foreign-born Hispanic mothers demonstrated substantially higher odds of delivering infants with anotia/microtia across nearly all strata of sociodemographic and other maternal factors (adjusted odds ratios range: 2.1-11.9). The odds of anotia/microtia was particularly elevated among Hispanic mothers who emigrated from Mexico after age five (adjusted odds ratios = 4.88; 95% confidence interval = 2.93-8.11) or who conducted the interview in Spanish (adjusted odds ratios = 4.97; 95% confidence interval = 3.00-8.24).

CONCLUSION

We observed that certain sociodemographic and acculturation factors are associated with higher risks of anotia/microtia among offspring of Hispanic mothers.

A modified panel of sentinel congenital anomalies for potential use in mutation epidemiology based on birth defects registry data

Since 1983, several authors have used panels of "sentinel" congenital anomalies that might serve as indicators of the human genome mutation rate. The current study suggests a considerably updated panel, and applies it to public health birth defects registry data to determine the potential number of de novo cases. Data were taken from deliveries in 1999-2009 from the Texas Birth Defects Registry, an active surveillance program. Cases with one of the conditions or syndromes in the panel were identified using codes and text searches. Frequencies and birth prevalence were calculated for the overall panel and subcategories within it. Of the 60 conditions appearing in previous papers on sentinel phenotypes, 21 (35%) were used in the current study along with 27 new phenotypes. We found 1,694 cases. Of those, 1,100 exhibited phenotypes thought to arise de novo in at least 90% of the cases ("all/almost all" subpanel), and 594 considered de novo in roughly 50-90% of cases ("most" subpanel). Chromosomal deletion disorders were present in 523 cases and imprinting disorders in 243. After adjusting for maternal age, occurrence of cases in the total panel, "most" subpanel, and imprinting disorders subpanel were significantly associated with paternal age. Our panel of sentinel phenotypes differs from previous panels due to evolved knowledge of genetic disorders, different approaches with respect to interviewing, and different operational definitions. It is hoped that using an overall panel as well as subpanels may maximize statistical power as well as suggest potential mechanisms.

Final results from the Betaseron (interferon β-1b) Pregnancy Registry: a prospective observational study of birth defects and pregnancy-related adverse events

OBJECTIVE

Women with multiple sclerosis are often diagnosed and treated during their reproductive years. Limited data are available on the safety of treatment during pregnancy. The Betaseron Pregnancy Registry prospectively monitored women exposed to interferon β-1b (IFNβ-1b) during pregnancy to estimate the rates of birth defects, spontaneous abortions (SABs) and other negative outcomes in this population.

DESIGN

From 2006 to 2011, this observational registry enrolled women exposed prior to conception or during pregnancy (but prior to or without abnormalities on prenatal screening). Follow-up continued from enrolment through the 4-month paediatric visit.

SETTING

Patients in the USA who met these criteria were enrolled in the registry.

RESULTS

The registry enrolled 99 pregnant women; 3 were lost to follow-up. The earliest exposure to IFNβ-1b occurred during the first trimester for 95 pregnancies and in the third trimester for 1 pregnancy. There were 99 birth outcomes (3 twins), including 86 (86.9%) live births, 11 (11.1%) SABs and 2 (2%) stillbirths. Birth defects were reported in five (5.1%) cases. Rates of birth defects and SAB were not significantly different from population comparators. No developmental concerns were identified at the 4-month paediatric visit.

CONCLUSIONS

The small sample size limits the ability to draw definitive conclusions; however, there was no pattern to suggest increased negative outcomes with IFNβ-1b.

CLINICAL TRIALS REGISTRATION NUMBER

NCT00317564.

De novo truncating mutations in AHDC1 in individuals with syndromic expressive language delay, hypotonia, and sleep apnea

Clinical whole-exome sequencing (WES) for identification of mutations leading to Mendelian disease has been offered to the medical community since 2011. Clinically undiagnosed neurological disorders are the most frequent basis for test referral, and currently, approximately 25% of such cases are diagnosed at the molecular level. To date, there are approximately 4,000 "known" disease-associated loci, and many are associated with striking dysmorphic features, making genotype-phenotype correlations relatively straightforward. A significant fraction of cases, however, lack characteristic dysmorphism or clinical pathognomonic traits and are dependent upon molecular tests for definitive diagnoses. Further, many molecular diagnoses are guided by recent gene-disease association discoveries. Hence, there is a critical interplay between clinical testing and research leading to gene-disease association discovery. Here, we describe four probands, all of whom presented with hypotonia, intellectual disability, global developmental delay, and mildly dysmorphic facial features. Three of the four also had sleep apnea. Each was a simplex case without a remarkable family history. Using WES, we identified AHDC1 de novo truncating mutations that most likely cause this genetic syndrome.

Loss-of-function HDAC8 mutations cause a phenotypic spectrum of Cornelia de Lange syndrome-like features, ocular hypertelorism, large fontanelle and X-linked inheritance

Cornelia de Lange syndrome (CdLS) is a multisystem genetic disorder with distinct facies, growth failure, intellectual disability, distal limb anomalies, gastrointestinal and neurological disease. Mutations in NIPBL, encoding a cohesin regulatory protein, account for >80% of cases with typical facies. Mutations in the core cohesin complex proteins, encoded by the SMC1A, SMC3 and RAD21 genes, together account for ∼5% of subjects, often with atypical CdLS features. Recently, we identified mutations in the X-linked gene HDAC8 as the cause of a small number of CdLS cases. Here, we report a cohort of 38 individuals with an emerging spectrum of features caused by HDAC8 mutations. For several individuals, the diagnosis of CdLS was not considered prior to genomic testing. Most mutations identified are missense and de novo. Many cases are heterozygous females, each with marked skewing of X-inactivation in peripheral blood DNA. We also identified eight hemizygous males who are more severely affected. The craniofacial appearance caused by HDAC8 mutations overlaps that of typical CdLS but often displays delayed anterior fontanelle closure, ocular hypertelorism, hooding of the eyelids, a broader nose and dental anomalies, which may be useful discriminating features. HDAC8 encodes the lysine deacetylase for the cohesin subunit SMC3 and analysis of the functional consequences of the missense mutations indicates that all cause a loss of enzymatic function. These data demonstrate that loss-of-function mutations in HDAC8 cause a range of overlapping human developmental phenotypes, including a phenotypically distinct subgroup of CdLS.

Descriptive epidemiology of selected heritable birth defects in Texas

BACKGROUND

Few population-based studies exist on descriptive epidemiologic characteristics of rare heritable birth defects. The number of birth defect cases in the Texas Birth Defects Registry (one of the largest active birth defects surveillance systems in the world) enabled us to examine six different heritable disorders (aqueductal stenosis, infantile polycystic kidney disease, achondroplasia, thanatophoric dwarfism, chondrodysplasia/dwarfism not otherwise specified (NOS), and osteogenesis imperfecta) for a variety of descriptive demographic variables.

METHODS

The Texas Birth Defects Registry was used to identify infants or fetuses with heritable birth defects. Crude prevalence rates were calculated and Poisson regression was used to test the association of each demographic variable (e.g., maternal age) with each of the selected genetic birth defects.

RESULTS

White non-Hispanics exhibited higher rates of achondroplasia and osteogenesis imperfecta than other race/ethnic groups. Lower maternal education level and to a lesser extent, paternal education level, was associated with higher rates of several disorders. The birth prevalence rate for achondroplasia decreased from 1999 through 2006.

CONCLUSION

The use of a large birth defects registry provides a sufficient count of cases to perform some basic epidemiologic analysis on selected rare heritable birth defects.

Association of microtia with maternal obesity and periconceptional folic acid use

The study objective was to examine the association of microtia with maternal intake of folic-acid-containing supplements and obesity. The study data included deliveries from 1997 to 2005 from the National Birth Defects Prevention Study. Non-syndromic cases of microtia were compared to non-malformed, population-based liveborn control infants, by estimating adjusted odds ratios (AORs) and 95% confidence intervals (CIs) from logistic regression models that included maternal race/ethnicity, education, and study site. Maternal obesity was only weakly associated with microtia. Maternal periconceptional intake of folic-acid-containing vitamin supplements reduced the risk for microtia, but only among non-obese women (OR: 0.63; 95% CI: 0.44-0.91). The reduced risk was stronger when analyses were restricted to isolated cases (OR: 0.51; 95% CI: 0.34-0.77), and it was independent of the level of maternal dietary folate intake. Adjusting for maternal race/ethnicity did not reveal alternative interpretations of this association. This analysis suggests that maternal periconceptional intake of folic-acid-containing supplements may provide protection from microtia for non-obese women.

Epidemiologic features and clinical subgroups of anotia/microtia in Texas

BACKGROUND

Few studies have investigated the epidemiologic features of clinically defined subgroups of anotia/microtia.

METHODS

Data on cases of anotia and/or microtia among 1999-2005 deliveries were obtained from the Texas Birth Defects Registry, a population-based active surveillance system. We determined crude and adjusted associations between selected factors and seven clinical subgroups of anotia/microtia.

RESULTS

In total, 742 cases were diagnosed with anotia and/or microtia, corresponding to a prevalence of 2.86 per 10,000 live births. Of those, 45% had no other major birth defect ("isolated"), 77% were unilateral, and 22% bilateral. Anotia alone made up 6%, whereas microtia made up 94%. Birth prevalence was higher with increasing maternal age and among Mexico-born Hispanics. Compared to white mothers, Hispanic mothers were two-to-three times more likely to have infants with all but the syndromic and bilateral groups (adjusted prevalence ratios [aPRs] = 2.05-2.61). Non-Hispanic blacks had significantly lower risk for total anotia/microtia, and for the isolated, unilateral, and microtia subgroups (aPRs = 0.42-0.64). Less educated mothers were three-to-four times more likely to have children with anotia (aPRs = 2.98 for less than high school, 3.97 for high school graduates). Males were more likely to be born with total anotia/microtia and with syndromic, unilateral, and microtia subtypes (aPRs = 1.27-1.41).

CONCLUSIONS

In Texas, most anotia/microtia cases were in the unilateral and microtia groups, and 45% were isolated. Several clinical subgroups exhibited higher prevalence in males and among older mothers. Relative to whites, blacks were at lower risk and Hispanics (especially Mexico-born mothers) were at higher risk for selected types of anotia/microtia.

Alcohol consumption by women before and during pregnancy

OBJECTIVES

To determine the prevalence, patterns, and predictors of alcohol consumption prior to and during various intervals of pregnancy in the U.S.

METHODS

Alcohol-related, pregnancy-related, and demographic data were derived from computer-assisted telephone interviews with 4,088 randomly selected control mothers from the National Birth Defects Prevention Study who delivered live born infants without birth defects during 1997-2002. Alcohol consumption rates and crude and adjusted odds ratios (OR) were calculated.

RESULTS

30.3% of all women reported drinking alcohol at some time during pregnancy, of which 8.3% reported binge drinking (4+ drinks on one occasion). Drinking rates declined considerably after the first month of pregnancy, during which 22.5% of women reported drinking, although 2.7% of women reported drinking during all trimesters of pregnancy and 7.9% reported drinking during the 3rd trimester. Pre-pregnancy binge drinking was a strong predictor of both drinking during pregnancy (adjusted OR = 8.52, 95% CI = 6.67-10.88) and binge drinking during pregnancy (adjusted OR = 36.02, 95% CI = 24.63-52.69). Other characteristics associated with both any drinking and binge drinking during pregnancy were non-Hispanic white race/ethnicity, cigarette smoking during pregnancy, and having an unintended pregnancy.

CONCLUSIONS

Our study revealed that drinking during pregnancy is fairly common, three times the levels reported in surveys that ask only about drinking during the month before the survey. Women who binge drink before pregnancy are at particular risk for drinking after becoming pregnant. Sexually active women of childbearing ages who drink alcohol should be advised to use reliable methods to prevent pregnancy, plan their pregnancies, and stop drinking before becoming pregnant.

Neonatal presentation of ventricular tachycardia and a Reye-like syndrome episode associated with disturbed mitochondrial energy metabolism

BACKGROUND

Hyperammonemia, hypoglycemia, hepatopathy, and ventricular tachycardia are common presenting features of carnitine-acylcarnitine translocase deficiency (Mendelian Inheritance in Man database: *212138), a mitochondrial fatty acid oxidation disorder with a lethal prognosis. These features have not been identified as the presenting features of mitochondrial cytopathy in the neonatal period.

CASE PRESENTATION

We describe an atypical presentation of mitochondrial cytopathy in a 2 day-old neonate. She presented with a Reye-like syndrome episode, premature ventricular contractions and ventricular tachycardia. Initial laboratory evaluation exhibited a large amount of 3-methylglutaconic acid on urine organic acid analysis, mild orotic aciduria and a nonspecific abnormal acylcarnitine profile. The evaluation for carnitine-acylcarnitine translocase deficiency and other fatty acid oxidation disorders was negative. The patient later developed a hypertrophic cardiomyopathy and continued to be affected by recurrent Reye-like syndrome episodes triggered by infections. A muscle biopsy exhibited signs of a mitochondrial cytopathy. During the course of her disease, her Reye-like syndrome episodes have subsided; however, cardiomyopathy has persisted along with fatigue and exercise intolerance.

CONCLUSIONS

This case illustrates that, in the neonatal period, hyperammonemia and ventricular tachycardia may be the presenting features of a lethal carnitine-acylcarnitine translocase deficiency or of a mitochondrial cytopathy, associated with a milder clinical course. This association broadens the spectrum of presenting phenotypes observed in patients with disturbed mitochondrial energy metabolism. Also, the presence of 3-methylglutaconic aciduria suggests mitochondrial dysfunction and mild orotic aciduria could potentially be used as a marker of mitochondrial disease.

Do infants with major congenital anomalies have an excess of macrosomia?

BACKGROUND

Infants that develop congenital anomalies may also have an excess prevalence of macrosomia (birth weight > or =4,000 g). This may indicate that abnormalities of glycemic control play a role in the etiology of birth defects. This study was undertaken to determine whether all infants with congenital anomalies have an excess of macrosomia and whether it is confined to specific types of anomalies.

METHODS

A case-control study was conducted, comparing the birth weights of 8,226 infants with congenital anomalies ascertained by the Texas Birth Defects Monitoring Division with those of 965,965 infants without birth defects. Odds ratios were calculated to determine the association between birth weight and congenital anomalies, for 45 specific defects, and for all these defects combined.

RESULTS

For all 45 defects combined, a significant association occurred only in the highest birth weight category. Infants with congenital anomalies were more likely than infants without birth defects to have a birth weight > or =4,500 g (OR = 1.65; 95% CI = 1.39-1.96). Infants born with ventricular septal defects, atrial septal defects, ventricular hypertrophy, or anomalies of the great vessels were 1.5-2.5 times more likely to weigh > or =4,000 g than were infants without birth defects. Based on small numbers, a stronger excess of macrosomia was observed for infants with encephalocele, holoprosencephaly, anomalies of the corpus callosum, preaxial polydactyly, and omphalocele.

CONCLUSIONS

Our data suggest that infants with specific congenital anomalies are more likely to be macrosomic than are infants without an anomaly. If these findings are confirmed, associations between macrosomia and specific types of birth defects may help to identify birth defects that are caused by alterations in glycemic control.

Frequency of prenatal diagnosis of birth defects in Houston, Galveston and the Lower Rio Grande Valley, Texas 1995

BACKGROUND

Estimates of the proportion of birth defects diagnosed before birth exist for only a few types of birth defects and for a few geographic regions in the United States. This population-based study examines rates of prenatal diagnosis for previously unstudied birth defects in a new geographic region.

METHODS

Active surveillance of 23 categories of birth defects among 111,902 infants born in 77 birthing hospitals in Texas in 1995 identified 852 infants or fetuses with major birth defects. Surveillance was conducted by the Texas Birth Defects Monitoring Program of the Texas Department of Health. Two regions were covered, the Houston/Galveston metropolitan area as well as the Lower Rio Grande Valley of Texas. Rates of prenatal diagnosis were evaluated for 23 different types of birth defects, using proportions and 95% confidence intervals.

RESULTS

One third of the 852 infants or fetuses with birth defects were prenatally diagnosed. Diagnosis rates varied greatly depending on the type of birth defects and were lower among infants born to Black and Hispanic women. More than 60% of anencephaly, encephalocele, gastroschisis and trisomies 13 and 18 were diagnosed antenatally. Many of the fetuses that were electively terminated had birth defects or combinations of birth defects that were potentially lethal. Prevalence rates for birth defects generally do not include fetuses that die or are electively terminated before 20 weeks of gestation. Thus, 36% of anencephaly, 21% of omphalocele, 15% of encephalocele and between 7 and 10% of spina bifida, hydrocephaly, renal agenesis, and trisomies 13, 18, and 21 were not included in our published rates.

CONCLUSIONS

Published rates for specific types of birth defects are spuriously low. This should be considered when investigating alleged clusters and comparing rates of birth defects across geographic areas. Since many elective abortions are for lethal or potentially lethal birth defects, a major effect of prenatal diagnosis is the resultant decrease in infant mortality attributable to birth defects.

Male cases of incontinentia pigmenti: case report and review

Male patients with Bloch-Sulzberger incontinentia pigmenti (IP type II) are rare and more severely affected than their female counterparts, with a significant occurrence of sex chromosome aneuploidy. This document introduces a new male IP type II patient and reviews 48 males reported with IP. Twenty-eight of the 49 patients meet current criteria for diagnosis of IP type II. The phenotype is variable and the incidence of documented developmental delay is 25%. Five patients had Klinefelter syndrome (47,XXY). Most patients were reported prior to 1961 when chromosome analysis was not available. Biopsy and laboratory reports considered to be "consistent with" the diagnosis of IP were seen in patients meeting criteria as well as those who would not currently be given the diagnosis. The histologic findings considered diagnostic are varied. This variability may be accounted for by differences in stage of disease, biopsy site, histologic technique, and reporting style. Conversely, this may indicate that the diagnostic weight given to the biopsy should be reconsidered. Eosinophilia was not a consistent finding. Overall, differences in reporting, ascertainment, and length of follow-up lead to difficulty in interpreting or predicting the natural history of males with IP type II. Based on the existing literature, they appear to have a higher rate of mental retardation than the general population, but there does not appear to be a correlation between severity of physical and mental involvement. The presence of sex chromosome aneuploidy documented in the more recent cases emphasizes the need for chromosome analysis in any male patient suspected of IP type II.

Selection against mutant alleles in blood leukocytes is a consistent feature in Incontinentia Pigmenti type 2

Incontinentia Pigmenti 2 (IP2) is an X-linked dominant disorder with male lethality. Affected females display a characteristic skin eruption that evolves through four classic stages, frequently accompanied by dental and retinal abnormalities. Non-random (skewed) X-inactivation in peripheral blood leukocytes and in fibroblasts has been observed in females with IP2; however, sample sizes have been small and methods of analysis varied. We have examined X-inactivation in a large group of multigenerational IP2 families, in smaller families, and in isolated cases. Ninety-eight percent of affected females in multigenerational IP2 pedigrees show completely skewed patterns of X-inactivation, while only approximately 10% of a normal control population is skewed. Results both in small families and in new mutation cases with subsequent segregation consistent with Xq28 linkage are similar. Isolated cases show a lower percentage (85%) of skewed affected individuals; this difference may be due to inaccurate clinical ascertainment. The parent of origin of new mutations could be determined in 15 families; paternal new mutations were twice as common as maternal. Fibroblast subclones from a biopsy at the boundary of a skin lesion in a newborn IP2 patient were isolated, and clones with either one or the other X active were identified, demonstrating that cells with the active disease-bearing X chromosome are still present in stage I skin lesions.

Gonadal mosaicism for incontinentia pigmenti in a healthy male

Incontinentia pigmenti (IP) is a genodermatosis that segregates as an X linked dominant trait with male lethality. The disease has been linked to Xq28 in a number of studies. A few affected males have been documented, most of whom have a 47,XXY karyotype. We report a family with two paternally related half sisters, each affected with IP. The father is healthy, clinically normal, and has a 46,XY normal male karyotype. Linkage analysis of 12 polymorphic markers (two X linked and 10 autosomal) confirms paternity. X inactivation studies with the human androgen receptor (HUMARA) indicate that the paternal X chromosome is inactivated preferentially in each girl, implying that this chromosome carries the IP mutation, and that the father is a gonadal mosaic for the IP mutation.

Involvement of the thymus and cellular immune system in craniofacial malformation syndromes

Craniofacial structures, the aortic arch, thymus, and parathyroid glands all arise from the embryologic pharyngeal pouches, and DiGeorge and Job craniofacial malformation syndromes have defined immunologic deficiencies. The question addressed by this study is whether patients with other pharyngeal pouch malformations could also have immunologic abnormalities. Twelve patients, 4 female and 8 male, were selected at random from the Tampa Bay Craniofacial Center. Their diagnoses included: cleft lip/cleft palate, hemifacial microsomia/Goldenhar syndrome, Treacher-Collins syndrome, craniofacial hemangiomata, cranio-synostosis syndromes, and Tessier 13 cleft. Fresh blood samples were analyzed against age-matched controls for immunoglobin number, using immunoelectrophoresis, T-cell, B-cell, and natural killer cell quantity via Coulter counter and monoclonal antibody labeling, as well as lymphocyte stimulation and response functions with phytohemagglutinin, concanavalin A, pokeweed mitogen, and Staphylococcus aureus mitogens. All patients studied had some abnormality of their immune systems. Seven had specific T-cell abnormalities and three patients had abnormalities in all three categories studied. This indicates that patients with any pharyngeal pouch malformation may have an abnormality of the immune system.