Analyzing clinical and genetic characteristics of a cohort with multiple congenital anomalies-hypotonia-seizures syndrome (MCAHS)

Spectrum of Multiple Congenital Anomalies-Hypotonia-Seizures Syndrome 3 (MCAHS3) Due to Phosphatidylinositol Glycan Biosynthesis Class T (PIGT) Gene Mutations: A Narrative Review

Multiple congenital anomalies-hypotonia-seizures syndrome 3 (MCAHS3) results from mutations in the phosphatidylinositol glycan biosynthesis class T (PIGT) gene leading to defects in glycosylphosphatidylinositol transamidase complex (GPI-TA) synthesis. Glycosylphosphatidylinositol serves as an anchor to more than 150 mammalian proteins for attachment on cell surfaces, enabling specific functional properties. Mutations in the PIGT gene result in disruption of this extremely important post-translational protein modification, yielding dysfunctional proteins leading to MCAHS3. An exhaustive literature search was conducted across various electronic databases to reveal only 41 reported cases of MCAHS3 worldwide, emphasizing the rarity of this condition. Multiple congenital anomalies-hypotonia-seizures syndrome 3 has been reported as secondary to 18 different known PIGT variants to date, manifesting as a varying spectrum of craniofacial dysmorphism, developmental delay with epilepsy, cardiac and renal malformations, and unique features in biochemical testing and neuroimaging. This review aims to highlight the constellation of clinical symptoms, diagnostic modalities, and management challenges associated with MCAHS3 cases. It would help determine optimal diagnostic and treatment strategies for newly identified cases and facilitate new research on this rare condition.

PIGN c.776T>C (p.Phe259Ser) variant present in trans with a pathogenic variant for PIGN-congenital disorder of glycosylation: Bella-Noah syndrome

Glycosylation is the most common protein and lipid post-translational modification in humans. Congenital disorders of glycosylation (CDG) are characterized by both genetic and clinical heterogeneity, presenting multisystemic manifestations, and in most cases are autosomal recessive in inheritance. The PIGN gene is responsible for the addition of phosphoethanolamine to the first mannose in the glycosylphosphatidylinositol (GPI)-anchor biosynthesis pathway, a highly conserved process that enables proteins to bind to the cell surface membrane. Here, we report a family with two siblings pediatric cases with the exact same compound heterozygous variants in PIGN. The (c.776T > C) variant of uncertain significance (VUS) together with a known pathogenic variant (c.932T > G), resulting in clinical features compatible with PIGN-related conditions, more specific the CDG. This is the first time that PIGN variant c.776T > C is reported in literature in individuals with PIGN-congenital disorder of glycosylation (PIGN-CDG), and the current submission in ClinVar by Invitae® is specifically of our case. Detailed clinical information and molecular analyses are presented. Here, we show for the first time two affected siblings with one pathogenic variant (c.932T > G) and the c.776T > C VUS in trans. In honor of the family, we propose the name Bella-Noah Syndrome for disorder.

Visfatin Affects the Transcriptome of Porcine Luteal Cells during Early Pregnancy

Visfatin/NAMPT (VIS), the hormone exerting a pleiotropic effect, is also perceived as an important factor in the regulation of reproductive processes and pregnancy maintenance. Previous studies confirmed its involvement in the control of porcine pituitary and ovary function. In this study, we hypothesized that VIS may affect the global transcriptome of luteal cells and thus regulate the functioning of the ovaries. Illumina's NovaSeq 6000 RNA sequencing was performed to investigate the differentially expressed genes (DEGs) and long non-coding RNAs (DELs) as well as the occurrence of differential alternative splicing events (DASs) in the porcine luteal cells exposed to VIS (100 ng/mL) during the implantation period. The obtained results revealed 170 DEGs (99 up- and 71 downregulated) assigned to 45 functional annotations. Moreover, we revealed 40 DELs, of which 3 were known and 37 were described for the first time. We identified 169 DASs events. The obtained results confirmed a significant effect of VIS on the transcriptome and spliceosome of luteal cells, including the genes involved in the processes crucial for successful implantation and pregnancy maintenance as angiogenesis, steroidogenesis, inflammation, cell development, migration, and proliferation.

Biallelic variants in PIGN cause Fryns syndrome, multiple congenital anomalies-hypotonia-seizures syndrome, and neurologic phenotypes: A genotype-phenotype correlation study

PURPOSE

Biallelic PIGN variants have been described in Fryns syndrome, multiple congenital anomalies-hypotonia-seizure syndrome (MCAHS), and neurologic phenotypes. The full spectrum of clinical manifestations in relation to the genotypes is yet to be reported.

METHODS

Genotype and phenotype data were collated and analyzed for 61 biallelic PIGN cases: 21 new and 40 previously published cases. Functional analysis was performed for 2 recurrent variants (c.2679C>G p.Ser893Arg and c.932T>G p.Leu311Trp).

RESULTS

Biallelic-truncating variants were detected in 16 patients-10 with Fryns syndrome, 1 with MCAHS1, 2 with Fryns syndrome/MCAHS1, and 3 with neurologic phenotype. There was an increased risk of prenatal or neonatal death within this group (6 deaths were in utero or within 2 months of life; 6 pregnancies were terminated). Incidence of polyhydramnios, congenital anomalies (eg, diaphragmatic hernia), and dysmorphism was significantly increased. Biallelic missense or mixed genotype were reported in the remaining 45 cases-32 showed a neurologic phenotype and 12 had MCAHS1. No cases of diaphragmatic hernia or abdominal wall defects were seen in this group except patient 1 in which we found the missense variant p.Ser893Arg to result in functionally null alleles, suggesting the possibility of an undescribed functionally important region in the final exon. For all genotypes, there was complete penetrance for developmental delay and near-complete penetrance for seizures and hypotonia in patients surviving the neonatal period.

CONCLUSION

We have expanded the described spectrum of phenotypes and natural history associated with biallelic PIGN variants. Our study shows that biallelic-truncating variants usually result in the more severe Fryns syndrome phenotype, but neurologic problems, such as developmental delay, seizures, and hypotonia, present across all genotypes. Functional analysis should be considered when the genotypes do not correlate with the predicted phenotype because there may be other functionally important regions in PIGN that are yet to be discovered.

Case report: Functional analysis of the p.Arg507Trp variant of the PIGT gene supporting the moderate epilepsy phenotype of mutations in the C-terminal region

Pathogenic germline variants in the PIGT gene are associated with the "multiple congenital anomalies-hypotonia-seizures syndrome 3" (MCAHS3) phenotype. So far, fifty patients have been reported, most of whom suffer from intractable epilepsy. Recently, a comprehensive analysis of a cohort of 26 patients with PIGT variants has broadened the phenotypical spectrum and indicated that both p.Asn527Ser and p.Val528Met are associated with a milder epilepsy phenotype and less severe outcomes. Since all reported patients are of Caucasian/Polish origin and most harbor the same variant (p.Val528Met), the ability to draw definitive conclusions regarding the genotype-phenotype correlation remains limited. We report a new case with a homozygous variant p.Arg507Trp in the PIGT gene, detected on clinical exome sequencing. The North African patient in question displays a predominantly neurological phenotype with global developmental delay, hypotonia, brain abnormalities, and well-controlled epileptic seizures. Homozygous and heterozygous variants in codon 507 have been reported to cause PIGT deficiency without biochemical confirmation. In this study, FACS analysis of knockout HEK293 cells that had been transfected with wild-type or mutant cDNA constructs demonstrated that the p.Arg507Trp variant leads to mildly reduced activity. Our result confirm the pathogenicity of this variant and strengthen recently reported evidence on the genotype-phenotype correlation of the PIGT variant.

Rare multiple congenital anomalies-hypotonia-seizures syndrome type 1 (MCAHS1) - the clinical and molecular summary

Multiple congenital anomalies-hypotonia-seizures syndrome type 1 (MCAHS1) is a rare autosomal recessive genetic disease belonging to glycosylphosphatidylinositols biosynthesis defects (GPIBD), a group of recessive disorders characterized by intellectual disability, hypotonia, and seizures. Glycosylphosphatidylinositols (GPIs) are glycolipids that anchor and remodel cell proteins. These processes are highly conserved and fundamental in the metabolism of all eukaryotes, including humans. Here, we have reported a male patient presenting with hypotonia, intellectual disability, and epilepsy, who underwent whole exome sequencing (WES). The analysis revealed the presence of two deleterious variants in PIGN that encodes GPI ethanolamine phosphate transferase-1 - one novel (c.1247_1251delAAGTG; p.Glu416Glyfs*22), and one that has been previously reported in the medical literature (c.1434+5G>A) resulting in MCAHS1. The detailed clinical assessment followed by the medical literature review also pointed out transient macrosomia and unreported in MCAHS1 advanced bone age and postnatal tall stature. These symptoms suggest that MCAHS1 shares a phenotypic overlap with disorders associated with overgrowth. To conclude, our case report and summary of the medical literature may be helpful for clinicians and geneticists who diagnose patients presenting with hypotonia accompanied by tall stature, advanced bone age, and transient macrosomia.

PIGN-Related Disease in Two Lithuanian Families: A Report of Two Novel Pathogenic Variants, Molecular and Clinical Characterisation

Background and Objectives: Pathogenic variants of PIGN are a known cause of multiple congenital anomalies-hypotonia-seizures syndrome 1 (MCAHS1). Many affected individuals have clinical features overlapping with Fryns syndrome and are mainly characterised by developmental delay, congenital anomalies, hypotonia, seizures, and specific minor facial anomalies. This study investigates the clinical and molecular data of three individuals from two unrelated families, the clinical features of which were consistent with a diagnosis of MCAHS1. Materials and Methods: Next-generation sequencing (NGS) technology was used to identify the changes in the DNA sequence. Sanger sequencing of gDNA of probands and their parents was used for validation and segregation analysis. Bioinformatics tools were used to investigate the consequences of pathogenic or likely pathogenic PIGN variants at the protein sequence and structure level. Results: The analysis of NGS data and segregation analysis revealed a compound heterozygous NM_176787.5:c.[1942G>T];[1247_1251del] PIGN genotype in family 1 and NG_033144.1(NM_176787.5):c.[932T>G];[1674+1G>C] PIGN genotype in family 2. In silico, c.1942G>T (p.(Glu648Ter)), c.1247_1251del (p.(Glu416GlyfsTer22)), and c.1674+1G>C (p.(Glu525AspfsTer68)) variants are predicted to result in a premature termination codon that leads to truncated and functionally disrupted protein causing the phenotype of MCAHS1 in the affected individuals. Conclusions: PIGN-related disease represents a wide spectrum of phenotypic features, making clinical diagnosis inaccurate and complicated. The genetic testing of every individual with this phenotype provides new insights into the origin and development of the disease.

PIGN encephalopathy: Characterizing the epileptology

OBJECTIVE

Epilepsy is common in patients with PIGN diseases due to biallelic variants; however, limited epilepsy phenotyping data have been reported. We describe the epileptology of PIGN encephalopathy.

METHODS

We recruited patients with epilepsy due to biallelic PIGN variants and obtained clinical data regarding age at seizure onset/offset and semiology, development, medical history, examination, electroencephalogram, neuroimaging, and treatment. Seizure and epilepsy types were classified.

RESULTS

Twenty six patients (13 female) from 26 families were identified, with mean age 7 years (range = 1 month to 21 years; three deceased). Abnormal development at seizure onset was present in 25 of 26. Developmental outcome was most frequently profound (14/26) or severe (11/26). Patients presented with focal motor (12/26), unknown onset motor (5/26), focal impaired awareness (1/26), absence (2/26), myoclonic (2/26), myoclonic-atonic (1/26), and generalized tonic-clonic (2/26) seizures. Twenty of 26 were classified as developmental and epileptic encephalopathy (DEE): 55% (11/20) focal DEE, 30% (6/20) generalized DEE, and 15% (3/20) combined DEE. Six had intellectual disability and epilepsy (ID+E): two generalized and four focal epilepsy. Mean age at seizure onset was 13 months (birth to 10 years), with a lower mean onset in DEE (7 months) compared with ID+E (33 months). Patients with DEE had drug-resistant epilepsy, compared to 4/6 ID+E patients, who were seizure-free. Hyperkinetic movement disorder occurred in 13 of 26 patients. Twenty-seven of 34 variants were novel. Variants were truncating (n = 7), intronic and predicted to affect splicing (n = 7), and missense or inframe indels (n = 20, of which 11 were predicted to affect splicing). Seven variants were recurrent, including p.Leu311Trp in 10 unrelated patients, nine with generalized seizures, accounting for nine of the 11 patients in this cohort with generalized seizures.

SIGNIFICANCE

PIGN encephalopathy is a complex autosomal recessive disorder associated with a wide spectrum of epilepsy phenotypes, typically with substantial profound to severe developmental impairment.

Spectrum of Neurological Symptoms in Glycosylphosphatidylinositol Biosynthesis Defects: Systematic Review

Background: Mutations of genes involved in the synthesis of glycosylphosphatidylinositol and glycosylphosphatidylinositol-anchored proteins lead to rare syndromes called glycosylphosphatidylinositol-anchored proteins biosynthesis defects. Alterations of their structure and function in these disorders impair often fundamental processes in cells, resulting in severe clinical image. This study aimed to provide a systematic review of GPIBD cases reports published in English-language literature.

Methods: The browsing of open-access databases (PubMed, PubMed Central. and Medline) was conducted, followed by statistical analysis of gathered information concerning neurological symptomatology. The inclusion criteria were: studies on humans, age at onset (<18 y.o.), and report of GPIBD cases with adequate data on the genetic background and symptomatology. Exclusion criteria were: publication type (manuscripts, personal communication, review articles); reports of cases of GPI biosynthesis genes mutations in terms of other disorders; reports of GPIBD cases concentrating on non-neurological symptoms; or articles concentrating solely on the genetic issues of GPI biosynthesis. Risk of bias was assessed using Joanna Brigs Institute Critical Appraisal Checklists. Data synthesis was conducted using STATISTICA 13.3.721.1 (StatSoft Polska Sp. z.o.o.). Used tests were chi-square, Fisher's exact test (for differences in phenotype), and Mann-Whitney U test (for differences in onset of developmental delay).

Results: Browsing returned a total of 973 articles which, after ruling out the repetitions and assessing the inclusion and exclusion criteria, led to final inclusion of 77 articles (337 GPIBD cases) in the analysis. The main outcomes were prevalence of neurological symptoms, onset and semiology of seizures and their response to treatment, and onset of developmental delay. Based on this data a synthesis of phenotypical differences between the groups of GPIBD cases and the general GPIBD cases population was made.

Discussion: A synthetical analysis of neurological components in clinical image of GPIBD patients was presented. It highlights the main features of these disorders, which might be useful in clinical practice for consideration in differential diagnosis with children presenting with early-onset seizures and developmental delay. The limitation of this review is the scarcity of the specific data in some reports, concerning the semiology and onset of two main features of GPIBD.

Evidence of the milder phenotypic spectrum of c.1582G>A PIGT variant: Delineation based on seven novel Polish patients

PIGT is one of over 29 glycosylphosphatidylinositol biosynthesis defect genes. Mutations cause genetically determined disorders characterized mainly by epilepsy with fever-sensitivity, central hypotonia, psychomotor delay and congenital malformations. The disease is known as multiple congenital anomalies-hypotonia-seizures syndrome 3 (MCAHS3) or glycosylphosphatidylinositol biosynthesis defect-7. Twenty-eight cases have been reported until today. We present seven novel Polish patients, all harboring 1582G>A variant in a homozygous or compound heterozygous state which seems to cause a milder phenotype of the disease.

Novel insights into the clinico-radiological spectrum of phenotypes associated to PIGN mutations

OBJECTIVES

Autosomic recessive mutations in the PIGN gene have been described in less than 30 subjects to date, in whom multiple congenital anomalies combined with severe developmental delay, hypotonia, epileptic encephalopathy, and cerebellar atrophy have been described as crucial features. A clear-cut neuroradiological characterization of this entity, however, is still lacking. We aim to present three pediatric PIGN mutated cases with an in-depth evaluation of their brain abnormalities.

METHODS

We present the neuroradiological, clinical, and genetic characterization of three Caucasian pediatric subjects with pathogenic/likely pathogenic variants in the PIGN gene revealed by Next Generation Sequencing analysis.

RESULTS

We identified three subjects (two siblings, one unrelated case) presenting with encephalopathy with early-onset epilepsy, hypotonia, and severe global developmental delay. No additional severe multiple congenital anomalies were detected. Neuroradiological evaluation showed extensive quantitative reduction of white matter, severe and progressive cortical atrophy, with frontal predominance and an anteroposterior gradient, combined with cerebellar and brainstem atrophy.

CONCLUSIONS

Our findings broaden and systematize the neuroradiological spectrum of abnormalities in PIGN related encephalopathy. Furthermore, our dataset confirms that mutations in PIGN gene appear to be pan-ethnic and represent an underestimated cause of early-onset encephalopathy.

Deep-Phenotyping the Less Severe Spectrum of PIGT Deficiency and Linking the Gene to Myoclonic Atonic Seizures

The two aims of this study were (i) to describe and expand the phenotypic spectrum of PIGT deficiency in affected individuals harboring the c.1582G>A; p.Val528Met or the c.1580A > G; p.Asn527Ser variant in either homozygous or compound heterozygous state, and (ii) to identify potential genotype-phenotype correlations and any differences in disease severity among individuals with and without the PIGT variants. The existing literature was searched to identify individuals with and without the two variants. A detailed phenotypic assessment was performed of 25 individuals (both novel and previously published) with the two PIGT variants. We compared severity of disease between individuals with and without these PIGT variants. Twenty-four individuals carried the PIGT variant Val528Met in either homozygous or compound heterozygous state, and one individual displayed the Asn527Ser variant in a compound heterozygous state. Disease severity in the individual with the Asn527Ser variant was compatible with that in the individuals harboring the Val528Met variant. While individuals without the Asn527Ser or Val528Met variant had focal epilepsy, profound developmental delay (DD), and risk of premature death, those with either of the two variants had moderate to severe DD and later onset of epilepsy with both focal and generalized seizures. Individuals homozygous for the Val528Met variant generally became seizure-free on monotherapy with antiepileptic drugs, compared to other PIGT individuals who were pharmaco-resistant. Two patients were diagnosed with myoclonic-atonic seizures, and a single patient was diagnosed with eyelid myoclonia. Our comprehensive analysis of this large cohort of previously published and novel individuals with PIGT variants broadens the phenotypical spectrum and shows that both Asn527Ser and Val528Met are associated with a milder phenotype and less severe outcome. Our data show that PIGT is a new candidate gene for myoclonic atonic epilepsy. Our genotype-phenotype correlation will be useful for future genetic counseling. Natural history studies of this mild spectrum of PIGT-related disorder may shed light on hitherto unknown aspects of this rare disorder.

Inherited glycosylphosphatidylinositol defects cause the rare Emm-negative blood phenotype and developmental disorders

Glycosylphosphatidylinositol (GPI) is a glycolipid that anchors >150 proteins to the cell surface. Pathogenic variants in several genes that participate in GPI biosynthesis cause inherited GPI deficiency disorders. Here, we reported that homozygous null alleles of PIGG, a gene involved in GPI modification, are responsible for the rare Emm-negative blood phenotype. Using a panel of K562 cells defective in both the GPI-transamidase and GPI remodeling pathways, we show that the Emm antigen, whose molecular basis has remained unknown for decades, is carried only by free GPI and that its epitope is composed of the second and third ethanolamine of the GPI backbone. Importantly, we show that the decrease in Emm expression in several inherited GPI deficiency patients is indicative of GPI defects. Overall, our findings establish Emm as a novel blood group system, and they have important implications for understanding the biological function of human free GPI.

PIGA Mutations Can Mimic Neonatal Hemochromatosis

Neonatal hemochromatosis (NH), one of the most common causes of liver failure in the neonate, often causes fetal loss or death during the neonatal period. Most cases are thought to be due to gestational alloimmune disease; however, other rare causes have been reported. NH is generally considered congenital and familial but not heritable. We present an infant diagnosed with NH whose clinical course differed significantly from that of most NH cases: at 11 months of age he had normal levels of liver enzymes, ferritin, and bilirubin, and normal neurodevelopment. This term male infant was born with a history of intrauterine growth restriction, oligohydramnios, and pericardial effusion. On day of life 1, he had hyperbilirubinemia and transaminitis; on day of life 3, ferritin was elevated; and on day of life 9, an MRI revealed iron deposits in the liver and renal cortex. Phenotypic features prompted a genetics consult. Whole-exome sequencing revealed a variant in the phosphatidylinositol glycan biosynthesis class A protein (PIGA) gene. Germ-line PIGA mutations are generally thought to be lethal in utero; however, there are reports of infants with PIGA mutations associated with dysmorphic features, neurologic manifestations, biochemical perturbations, and systemic iron overload; development can be normal up to 6 months of age. Because of the differences between infants with NH versus PIGA germ-line mutations in inheritance, prognosis, and natural history of disease, we propose that PIGA gene testing should be considered when evaluating newborns who present with NH.

Congenital Disorders of Glycosylation from a Neurological Perspective

Most plasma proteins, cell membrane proteins and other proteins are glycoproteins with sugar chains attached to the polypeptide-glycans. Glycosylation is the main element of the post-translational transformation of most human proteins. Since glycosylation processes are necessary for many different biological processes, patients present a diverse spectrum of phenotypes and severity of symptoms. The most frequently observed neurological symptoms in congenital disorders of glycosylation (CDG) are: epilepsy, intellectual disability, myopathies, neuropathies and stroke-like episodes. Epilepsy is seen in many CDG subtypes and particularly present in the case of mutations in the following genes: ALG13, DOLK, DPAGT1, SLC35A2, ST3GAL3, PIGA, PIGW, ST3GAL5. On brain neuroimaging, atrophic changes of the cerebellum and cerebrum are frequently seen. Brain malformations particularly in the group of dystroglycanopathies are reported. Despite the growing number of CDG patients in the world and often neurological symptoms dominating in the clinical picture, the number of performed screening tests eg transferrin isoforms is systematically decreasing as broadened genetic testing is recently more favored. The aim of the review is the summary of selected neurological symptoms in CDG described in the literature in one paper. It is especially important for pediatric neurologists not experienced in the field of metabolic medicine. It may help to facilitate the diagnosis of this expanding group of disorders. Biochemically, this paper focuses on protein glycosylation abnormalities.

Deciphering the premature mortality in PIGA-CDG - An untold story

OBJECTIVE

Congenital disorder of glycosylation (CDG) due to a defective phosphatidylinositol glycan anchor biosynthesis class A protein (PIGA) is a severe X-linked developmental and epileptic encephalopathy. Seizures are often treatment refractory, and patients have intellectual disability and global developmental delay. Previous reports have suggested that patients with PIGA-CDG have a high risk of premature mortality. This study aimed to evaluate the observed high mortality and the causes of death in PIGA-CDG patients.

METHODS

We reviewed the literature and collected additional unpublished patients through an international network.

RESULTS

In total, we reviewed the data of 88 patients of whom 30 patients born alive were deceased, and the overall mortality before the age of 20 years was 30 % (26/88). Age at death ranged from 15 days to 48 years of life. The median age at death was two years and more than half of the patients deceased in early childhood. The PIGA-specific mortality rate/1000 person-years was 44.9/1000 person-years (95 %, CI 31.4-64.3). There were no cases of definite or probable sudden unexpected death in epilepsy (SUDEP) and half of the patients died due to respiratory failure (15/30, 50 %) or possible SUDEP (3/30, 10 %). Three patients (10 %) died from severe cardiomyopathy, liver failure and gastrointestinal bleeding, respectively. The cause of death was unclassified in nine patients (30 %). Autopsies were rarely performed and the true cause of death remains unknown for the majority of patients.

SIGNIFICANCE

Our data indicate an increased risk of premature death in patients with PIGA-CDG when compared to most monogenic developmental and epileptic encephalopathies.

Case Report: Compound Heterozygous Phosphatidylinositol-Glycan Biosynthesis Class N (PIGN) Mutations in a Chinese Fetus With Hypotonia-Seizures Syndrome 1

Multiple congenital anomalies-hypotonia-seizures syndrome 1 (MCAHS1) caused by phosphatidylinositol-glycan biosynthesis class N (PIGN) mutations is an autosomal recessive disease involving many systems of the body, such as the urogenital, cardiovascular, gastrointestinal, and central nervous systems. Here, compound heterozygous variants NM_012327.6:c.2427-2A > G and c.963G > A in PIGN were identified in a Chinese proband with MCAHS1. The features of the MCAHS1 family proband were evaluated to understand the mechanism of the PIGN mutation leading to the occurrence of MCAHS1. Ultrasound was conducted to examine the fetus, and his clinical manifestations were evaluated. Genetic testing was performed by whole-exome sequencing and the results were verified by Sanger sequencing of the proband and his parents. Reverse transcription-polymerase chain reaction was performed, and the products were subjected to Sanger sequencing. Quantitative PCR (Q-PCR) was conducted to compare gene expression between the patient and wild-type subjects. The compound heterozygous mutation NM_012327.6:c.2427-2A > G and c.963G > A was identified by whole-exome sequencing and was confirmed by Sanger sequencing. The NM_012327.6:c.2427-2A > G mutation led to skipping of exon 26, which resulted in a low expression level of the gene, as measured by Q-PCR. These findings provided a basis for genetic counseling and reproduction guidance in this family. Phenotype-genotype correlations may be defined by an expanded array of mutations.